OSA's Digital Library

Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 5 — Mar. 11, 2013
  • pp: 6401–6408
« Show journal navigation

Reconfigurable UWB pulse generator based on pulse shaping in a nonlinear optical loop mirror and differential detection

Tianye Huang, Songnian Fu, Jia Li, Lawrence R Chen, Ming Tang, Perry Shum, and Deming Liu  »View Author Affiliations


Optics Express, Vol. 21, Issue 5, pp. 6401-6408 (2013)
http://dx.doi.org/10.1364/OE.21.006401


View Full Text Article

Acrobat PDF (1487 KB)





Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations

Abstract

A reconfigurable impulse radio ultra-wideband (UWB) pulse generator for various UWB shapes (e.g., monocycle, doublet, and triplet pulses) based on a nonlinear optical loop mirror (NOLM) and differential detection is proposed and experimentally demonstrated. The proposed approach can be used with different modulation formats and may be suitable for implementation in future low-cost, high-speed, short-range UWB wireless access applications.

© 2013 OSA

1. Introduction

Ultra-wideband (UWB) impulse radio technology has attracted considerable interest for its applications in short-range, high-throughput, and high capacity wireless personal area networks and sensor networks, due to advantages such as low cost, immunity to multi-path fading, and feasibility of sharing bandwidth with existing wireless systems [1

1. D. Porcino, P. Research, and W. Hirt, “Ultra-wideband radio technology: potential and challenges ahead,” IEEE Commun. Mag. 41(7), 66–74 (2003). [CrossRef]

]. In 2002, the US Federal Communications Commission (FCC) approved the unlicensed use of the UWB spectrum from 3.1 to 10.6 GHz with a power spectral density (PSD) lower than −41.3 dBm/MHz. Based on these FCC regulations, a UWB signal must have a spectral bandwidth greater than 500 MHz or a fractional bandwidth greater than 20% [2

2. Federal Communications Commission, “Revision of part 15 of the commission's rules regarding ultra-wideband transmission systems,” Tech. Rep. ET- Docket 98–153, FCC02–48, (2002).

]. Until now, existing techniques of impulse radio UWB pulse generation can be classified into two approaches: electric and photonic. While it is possible to generate Gaussian pulses directly in the electrical domain, it is more challenging to obtain more complex UWB waveforms such as monocycle, doublet, and triplet pulses. As such, there has been considerable effort in developing photonic approaches for UWB pulse generation. Photonic approaches also have the advantages of supporting wide bandwidth and being tunable, reconfigurable, as well as compatible with fiber-optic transmission. Various photonic approaches have been proposed to generate UWB pulses, using cross gain and cross phase modulation (XGM/XPM) in a semiconductor optical amplifier (SOA) [3

3. Q. Wang, F. Zeng, S. Blais, and J. Yao, “Optical ultrawideband monocycle pulse generation based on cross-gain modulation in a semiconductor optical amplifier,” Opt. Lett. 31(21), 3083–3085 (2006). [CrossRef] [PubMed]

5

5. F. Wang, J. Dong, E. Xu, and X. Zhang, “All-optical UWB generation and modulation using SOA-XPM effect and DWDM-based multi-channel frequency discrimination,” Opt. Express 18(24), 24588–24594 (2010). [CrossRef] [PubMed]

]; frequency-to-time mapping [6

6. H. Y. Jiang, L. S. Yan, J. Ye, W. Pan, B. Luo, Z. Y. Chen, X. H. Zou, and X. S. Yao, “Photonic generation of impulse ultrawideband signals with switchable shapes and polarities based on frequency-to-time mapping,” Opt. Lett. 37(24), 5052–5054 (2012). [CrossRef] [PubMed]

9

9. M. Abtahi, M. Mirshafiei, J. Magné, L. A. Rusch, and S. LaRochelle, “Ultra-wideband waveform generator based on optical pulse-shaping and FBG Tuning,” IEEE Photon. Technol. Lett. 20(2), 135–137 (2008). [CrossRef]

]; phase-to-intensity (PM-IM) modulation conversion [10

10. X. Feng, Z. Li, B. O. Guan, C. Lu, H. Y. Tam, and P. K. A. Wai, “Switchable UWB pulse generation using a polarization maintaining fiber Bragg grating as frequency discriminator,” Opt. Express 18(4), 3643–3648 (2010). [CrossRef] [PubMed]

13

13. E. Zhou, X. Xu, K. Lui, and K. K. Wong, “A Power-Efficient Ultra-wideband Pulse Generator Based on Multiple PM-IM Conversions,” IEEE Photon. Technol. Lett. 22(14), 1063–1065 (2010). [CrossRef]

]; microwave photonic delay line filters [14

14. Q. Wang and J. Yao, “Switchable optical UWB monocycle and doublet generation using a reconfigurable photonic microwave delay-line filter,” Opt. Express 15(22), 14667–14672 (2007). [CrossRef] [PubMed]

16

16. M. Bolea, J. Mora, B. Ortega, and J. Capmany, “Optical UWB pulse generator using an N tap microwave photonic filter and phase inversion adaptable to different pulse modulation formats,” Opt. Express 17(7), 5023–5032 (2009). [CrossRef] [PubMed]

]; direct current modulation of semiconductor lasers [17

17. V. Torres-Company, K. Prince, and I. T. Monroy, “Fiber transmission and generation of ultrawideband pulses by direct current modulation of semiconductor lasers and chirp-to-intensity conversion,” Opt. Lett. 33(3), 222–224 (2008). [CrossRef] [PubMed]

, 18

18. H. Lv, Y. Yu, T. Shu, D. Huang, S. Jiang, and L. P. Barry, “Photonic generation of ultra-wideband signals by direct current modulation on SOA section of an SOA-integrated SGDBR laser,” Opt. Express 18(7), 7219–7227 (2010). [CrossRef] [PubMed]

]; sum-frequency generation in periodically poled lithium niobate waveguides [19

19. J. Wang, Q. Sun, J. Sun, and W. Zhang, “All-optical UWB pulse generation using sum-frequency generation in a PPLN waveguide,” Opt. Express 17(5), 3521–3530 (2009). [CrossRef] [PubMed]

]; the nonlinear transmission region of an electro-optic modulator [20

20. Q. Wang and J. Yao, “UWB doublet generation using nonlinearly biased electro-optic intensity modulator,” Electron. Lett. 42(22), 1304–1305 (2006). [CrossRef]

]; and various effects in highly nonlinear fiber (HNLF) such as pulse shaping with a nonlinear optical loop mirror (NOLM) [21

21. H. Huang, K. Xu, J. Q. Li, J. Wu, X. B. Hong, and J. T. Lin, “UWB pulse generation and distribution using NOLM based optical switch,” J. Lightwave Technol. 26(15), 2635–2640 (2008). [CrossRef]

], nonlinear polarization rotation [22

22. Y. M. Chang, J. Lee, and J. H. Lee, “Ultrawideband doublet pulse generation based on nonlinear polarization rotation of an elliptically polarized beam and its distribution over a fiber/wireless link,” Opt. Express 18(19), 20072–20085 (2010). [CrossRef] [PubMed]

], four-wave mixing (FWM) [23

23. W. Li, L. X. Wang, W. Hofmann, N. H. Zhu, and D. Bimberg, “Generation of ultra-wideband triplet pulses based on four-wave mixing and phase-to-intensity modulation conversion,” Opt. Express 20(18), 20222–20227 (2012). [CrossRef] [PubMed]

], and parametric amplification [24

24. J. Li, B. Kuo, and K. Wong, “Ultra-wideband pulse generation based on cross-gain modulation in fiber optical parametric amplifier,” IEEE Photon. Technol. Lett. 21(4), 212–214 (2009). [CrossRef]

]. However, without proper power attenuation, the frequency spectra of the UWB pulses generated by most existing methods may not fully satisfy the FCC spectral mask. As a result, the UWB signals may be too weak so that the wireless transmission distance is limited. Besides the FCC-specific spectral mask, it is also desirable for the UWB pulse generators to be reconfigurable so that different modulation formats such as on-off keying (OOK), pulse shape modulation (PSM), bi-phase modulation (BPM), and pulse position modulation (PPM) can be used. Several switchable UWB pulse generators have been reported in [5

5. F. Wang, J. Dong, E. Xu, and X. Zhang, “All-optical UWB generation and modulation using SOA-XPM effect and DWDM-based multi-channel frequency discrimination,” Opt. Express 18(24), 24588–24594 (2010). [CrossRef] [PubMed]

7

7. C. Wang, F. Zeng, and J. Yao, “All-fiber ultrawideband pulse generation based on spectral shaping and dispersion-induced frequency-to-time conversion,” IEEE Photon. Technol. Lett. 19(3), 137–139 (2007). [CrossRef]

, 9

9. M. Abtahi, M. Mirshafiei, J. Magné, L. A. Rusch, and S. LaRochelle, “Ultra-wideband waveform generator based on optical pulse-shaping and FBG Tuning,” IEEE Photon. Technol. Lett. 20(2), 135–137 (2008). [CrossRef]

12

12. S. Wang, H. Chen, M. Xin, M. Chen, and S. Xie, “Optical ultra-wide-band pulse bipolar and shape modulation based on a symmetric PM-IM conversion architecture,” Opt. Lett. 34(20), 3092–3094 (2009). [CrossRef] [PubMed]

, 14

14. Q. Wang and J. Yao, “Switchable optical UWB monocycle and doublet generation using a reconfigurable photonic microwave delay-line filter,” Opt. Express 15(22), 14667–14672 (2007). [CrossRef] [PubMed]

16

16. M. Bolea, J. Mora, B. Ortega, and J. Capmany, “Optical UWB pulse generator using an N tap microwave photonic filter and phase inversion adaptable to different pulse modulation formats,” Opt. Express 17(7), 5023–5032 (2009). [CrossRef] [PubMed]

, 23

23. W. Li, L. X. Wang, W. Hofmann, N. H. Zhu, and D. Bimberg, “Generation of ultra-wideband triplet pulses based on four-wave mixing and phase-to-intensity modulation conversion,” Opt. Express 20(18), 20222–20227 (2012). [CrossRef] [PubMed]

]. For example, a UWB pulse generator based on pulse shaping and fiber Bragg gratings (FBGs) has been demonstrated in [9

9. M. Abtahi, M. Mirshafiei, J. Magné, L. A. Rusch, and S. LaRochelle, “Ultra-wideband waveform generator based on optical pulse-shaping and FBG Tuning,” IEEE Photon. Technol. Lett. 20(2), 135–137 (2008). [CrossRef]

]. However, such an all-fiber implementation requires mode-locked fiber lasers and specially designed spectral-shaping components. Bolea et al. reported a reconfigurable UWB pulse generator which can be applied to different pulse modulation formats using an N tap microwave photonic filter [16

16. M. Bolea, J. Mora, B. Ortega, and J. Capmany, “Optical UWB pulse generator using an N tap microwave photonic filter and phase inversion adaptable to different pulse modulation formats,” Opt. Express 17(7), 5023–5032 (2009). [CrossRef] [PubMed]

]. In principle, such a scheme can be used to produce any higher-order UWB pulse, but the number of lasers required increases with the number of filter taps, e.g., in order to generate triplet pulses, 4 lasers with equal wavelength spacing are needed. Li et al. presented an approach for generating UWB triplet pulses by employing four-wave mixing (FWM) and PM-IM conversion [23

23. W. Li, L. X. Wang, W. Hofmann, N. H. Zhu, and D. Bimberg, “Generation of ultra-wideband triplet pulses based on four-wave mixing and phase-to-intensity modulation conversion,” Opt. Express 20(18), 20222–20227 (2012). [CrossRef] [PubMed]

]. The major restriction with this approach is that the UWB pulse generated at the idler wavelength may suffer from low signal-to-noise ratio (SNR) due to low FWM efficiency.

In this paper, we propose and experimentally demonstrate a reconfigurable UWB pulse generator to produce UWB monocycle, doublet, and triplet pulses with inverted polarity. The operation principle lies in the ability to shape pulses using the different transfer functions of a NOLM by adjusting the state of polarization (SOP) of the pump and probe signals. The NOLM output can be further shaped to produce monocycle or triplet pulses after differential detection. In addition, various modulation formats including OOK, PSM, BPM, and PPM can take advantage of our proposed UWB pulse generator.

2. Operation principle and experiment setup

We use a NOLM for pulse shaping as shown in Fig. 1(a)
Fig. 1 (a) NOLM configuration. (b) Pulse shaping effect with different transfer functions. (c) Simulation of the NOLM transfer function for different values of φ.
. Generally, the NOLM incorporates a section of highly nonlinear fiber (HNLF), a polarization controller (PC), two WDM couplers, and a 3-dB coupler. The probe and pump signals are launched into the NOLM through the 3-dB coupler and WDM coupler 1, respectively. WDM coupler 2 is used to couple out the pump. The probe is split into the clockwise (CW) and counter-clockwise (CCW) components as follows:
Ecw=22Ein=22(Einx+Einy)
(1)
Eccw=22Eineπ2i=22(Einx+Einy)eπ2i
(2)
where, EinxandEinyare the x and y polarization components of the input probe signalEin.

When a pump Epis launched into the NOLM, both the CW and CCW light will experience a nonlinear phase shift due to XPM in the HNLF. The nonlinear phase shift experienced by the CW probe is determined by the instantaneous optical power of the pump, while the nonlinear phase shift experienced by the CCW probe is determined by the average optical power of the pump. If the duty cycle of the pump pulse is very small, the nonlinear phase shift of the CCW probe is much smaller than that of the CW probe. As a result, the corresponding nonlinear phase shift can be neglected. Moreover, the nonlinear phase shift induced by self-phase modulation (SPM) on the probe can also be neglected owing to the relatively weak probe power. The nonlinear phase shift of the CW probe induced via XPM depends on the SOP of both the pump and probe. As such, the PC is an essential component and its role in determining the NOLM transfer function can be described by the product of two matrices [25

25. A. Bogoni, M. Scaffardi, P. Ghelfi, and L. Poti, “Nonlinear optical loop mirrors: investigation solution and experimental validation for undesirable counterpropagating effects in all-optical signal processing,” IEEE J. Sel. Top. Quantum Electron. 10(5), 1115–1123 (2004). [CrossRef]

]:
M1=(100eiφ)M2=(cosθsinθsinθcosθ)
(3)
where φ is the static phase shift between the two orthogonal SOPs induced by the PC and θ presents a polarization rotation effect. The electric fields of the output probe from the NOLM, Ecwoutand Eccwout, can be expressed as:
Ecwout=12(M2M1)(eiϕCWx00eiϕCWy)(EinxEiny)=12(EinxcosθeiϕCWxEinysinθei(ϕCWyφ)EinxsinθeiϕCWx+Einycosθei(ϕCWyφ))
(4)
Eccwout=12(1001)(M1M2)(EinxEiny)eiπ=12(EinxcosθEinysinθEinxsinθeiφ+Einycosθeiφ)
(5)
where, ϕCWx and ϕCWy are the nonlinear phase shifts of the CW signals along the two orthogonal polarization axes. After interference in the 3-dB coupler, the output power Poutof the NOLM is:

Pout=|22(Ecwout+Eccwout)|2
(6)

The NOLM output is determined by many parameters including the SOPs of the pump and probe, pump power, phase shift φ, and polarization rotation θ. In particular, if the SOP of the pump and probe are set to be parallel and if θ = π/2, the NOLM transfer function will change for different values of φ, which are controlled by the PC. For example, when φ = π, we obtain the conventional transmission curve of the NOLM, as shown in Fig. 1(b). This is the well-known transfer function which is often exploited for wavelength conversion applications (e.g., a pump pulse with a Gaussian profile can be transferred to the probe wavelength). On the other hand, for φ set to different values, the NOLM transfer function can be used to generate UWB doublet pulses, as shown in Fig. 1(b) and 1(c), i.e., varying φ allows us to set the operating bias point of the transfer function. As a result, for a Gaussian pump pulse with a fixed power, the NOLM output can be switched between a Gaussian and a doublet pulse by properly setting the PC.

It is well known that a monocycle pulse can be obtained by differentiating a Gaussian pulse; this first-order derivative can be approximated by a first-order difference realized using a 2-tap microwave delay line filter with tap coefficients (1, −1). Accordingly, a triplet pulse can be obtained by differentiating a doublet pulse, or equivalently by implementing a first-order difference to the doublet pulse [14

14. Q. Wang and J. Yao, “Switchable optical UWB monocycle and doublet generation using a reconfigurable photonic microwave delay-line filter,” Opt. Express 15(22), 14667–14672 (2007). [CrossRef] [PubMed]

]. We use an optical tunable delay line (OTDL) and a balanced photodetector (PD) to function as a 2-tap microwave delay line filter for the purpose of generating UWB monocycle and triplet pulses, as shown in Fig. 2
Fig. 2 Concept for monocycle and triplet pulse generation.
. Recall that doublet pulses can be shaped directly at the output of the NOLM by adjusting the PC; therefore, only one branch of the balanced PD is needed to convert the pulses from the optical domain to the electrical domain. Using the combination of the NOLM and balanced PD, monocycle, doublet, and triplet pulses can be obtained using our proposed setup.

Figure 3
Fig. 3 Experimental setup of the proposed reconfigurable UWB pulse generator.
shows the experimental setup for our proposed reconfigurable UWB pulse generator. An external cavity laser (ECL) at 1559.7 nm is modulated using a Mach-Zehnder modulator (MZM) driven by a pulse pattern generator (PPG) to create a train of Gaussian-like pulses with a repetition rate of 2.5 GHz. The Gaussian pulse train is then amplified by an EDFA and launched into the NOLM through a WDM coupler (WDM 1). A second WDM coupler (WDM 2) is used to remove the pump from the NOLM. The HNLF used in the NOLM has a length of 1007 m with a nonlinear coefficient 12.5 W−1km−1, a chromatic dispersion of 0.02 ps/(nm⋅km) at 1550 nm, and a dispersion slope of −0.01 ps/(nm2⋅km) at 1550 nm. We use PC2 to control the SOPs of the pump and probe, and hence the NOLM transfer function, to obtain either wavelength conversion or doublet pulse generation from the Gaussian pump. A probe signal at 1539.1 nm from a second ECL (ECL2) is injected into the NOLM through 3-dB coupler 1. The output of the NOLM is divided into two branches: one is connected to an OTDL for relative delay adjustment, while the second is connected to a variable optical attenuator (VOA) to adjust the power level. After differential detection using a 40 GHz balanced PD, both time-domain waveforms and electrical spectra are measured by a digital communications analyzer (DCA) using an electrical sampling module with a bandwidth of 80 GHz and an electrical spectrum analyzer (ESA) with a bandwidth of 40 GHz.

3. Results and discussion

To generate UWB monocycle pulses, we bias the NOLM to function as a wavelength convertor. In this case, the pump power was amplified to 12.4 dBm while the probe power was set at 2 dBm. By adjusting the relative delay and power levels prior to differential detection, UWB monocycles are obtained at the output of the balanced PD. The time domain waveforms and corresponding RF spectra are shown in Fig. 4(a)
Fig. 4 (a), (c), (e), (g) Measured waveforms and (b), (d), (f), (h) corresponding RF spectra of the generated UWB monocycle and doublet pulses. (RBW: 300 kHz)
-4(d). We use the normalized FCC mask (red-dash line) which is normalized to the RF components with maximum power in the region from 3.1 GHz to 10.6 GHz to illustrate how well the spectra of the generated UWB waveforms comply with the FCC mask [9

9. M. Abtahi, M. Mirshafiei, J. Magné, L. A. Rusch, and S. LaRochelle, “Ultra-wideband waveform generator based on optical pulse-shaping and FBG Tuning,” IEEE Photon. Technol. Lett. 20(2), 135–137 (2008). [CrossRef]

]. Note that polarity-inverted monocycle pulses can be obtained by tuning the OTDL. The center frequency and 10 dB bandwidth of the generated UWB monocycle pulses are approximately 4 GHz and 9.5 GHz, respectively, yielding a fractional bandwidth of 212.5%. To generate UWB doublet pulses, as mentioned above, PC2 was adjusted to control the NOLM transfer function accordingly and only one branch of the balanced PD was connected to the NOLM output. The polarity of the doublet pulses can be reversed by exciting the appropriate branch of the balanced PD. The results are shown in Fig. 4(e)-4(g). The central frequency is 8.8 GHz and the 10 dB bandwidths of the polarity-inverted doublet pulses are 9.5 GHz and 11 GHz, corresponding to fractional bandwidths of 107.9% and 137.5%. It is known that the RF spectra of the monocycle pulse and doublet pulse cannot fully satisfy the FCC mask; however, the main spectral content lies within the FCC mask, so that the waveforms can be used in less power-critical applications. In our proposed system, in addition to UWB monocycle and doublet pulses, more complex waveforms such as triplet pulses can also be generated. By biasing the PC within the NOLM and enabling the two branches of the balanced PD, we obtain UWB triplet pulses as shown in Fig. 5
Fig. 5 (a), (c) Measured waveforms and (b), (d) corresponding RF spectra of the generated UWB triplet pulses. (RBW: 300 kHz)
. Clearly, the RF spectra of the triplet pulses satisfy the FCC mask fully, compared with the monocycle and doublet pulses without modulation. The central frequency and 10 dB bandwidth are 7.5 GHz and 8.7 GHz, respectively, and the fractional bandwidth is 116%. Note that for modulated UWB signals, such as the OOK modulation, the RF spectrum will exhibit frequency spectral content below 2.5 GHz, as shown in Fig. 6(a)
Fig. 6 (a) eye diagram and (b) its corresponding RF spectral at the output of the NOLM; (c) eye diagram and (b) its corresponding RF spectrum after 10-km SSMF transmission. (e) Measured BER of back-to-back and after 10 km SSMF transmission.
-6(b). These lower-frequency components may not be easily handled in the optical domain. However, they can be suppressed by exploiting well-designed antennas, e.g., those that have a frequency response with a flat top in the UWB band and a deep notch in the lower-frequency region [26

26. S. Pan and J. Yao, “UWB-over-fiber communications: Modulation and transmission,” J. Lightwave Technol. 28(16), 2445–2455 (2010). [CrossRef]

]. In order to evaluate the transmission performance of our proposed UWB pulse generator, we have also performed a bit-error-ratio (BER) measurement for OOK-modulated doublet pulses over 10-km standard single mode fiber (SSMF). The eye diagrams, RF spectra, and BER performance are shown in Fig. 6. The 10 dB bandwidth and central frequency are maintained well. Meanwhile, we can obtain an error-free transmission with a power penalty of around 1.6 dB, compared with the back-to-back measurement.

A flexible UWB pulse generator must have the capability to implement various modulation formats upon request. The flexibility of our scheme enables most existing modulation formats. In addition to OOK modulation demonstrated above, the pulse shape can be switched between monocycle and triplet pulses by tuning PC2, yielding the possibility for implementing PSM. To achieve high-speed PSM, we can replace the PC2 inside the NOLM with a polarization modulator (PolM) sandwiched by two PCs to realize PSM. After setting two PCs properly, the phase shift ѱ induced by the PolM will follow the same operation principle in order to realize wavelength conversion or nonlinear pulse shaping. Therefore, by applying the data signal to the PolM, we can realize high speed PSM. Currently, the speeds of commercial PolMs can operate fast as 40 Gb/s [27

27. J. D. Bull, N. A. F. Jaeger, H. Kato, M. Fairburn, A. Reid, and P. Ghanipour, “40 GHz electro-optic polarization modulator for fiber optic communication systems,” Proc. SPIE 5577, 133–143 (2004). [CrossRef]

], which is sufficient for our scheme. As demonstrated in section 3, polarity-inverted UWB pulses can be obtained. These features are attractive as the proposed setup can be easily applied to BPM with monocycle and triplet pulses by adjusting the OTDL. Switching times below 10 µs based on thermal tuning were demonstrated in [28

28. P. A. Morton, J. Cardenas, J. B. Khurgin, and M. Lipson, “Fast thermal switching of wideband optical delay line with no long-term transient,” IEEE Photon. Technol. Lett. 24(6), 512–514 (2012). [CrossRef]

]. According to state-of-art techniques, rapidly tunable dealy lines can be implemented, using electro-optic effects (via p-n junction diodes) in a rib waveguide-based OTDL [29

29. S. Khan, M. A. Baghban, and S. Fathpour, “Electronically tunable silicon photonic delay lines,” Opt. Express 19(12), 11780–11785 (2011). [CrossRef] [PubMed]

]. Currently, PPM is another commonly used modulation format for UWB communication system [30

30. J. H. Reed Christopher, An introduction to Ultra Wideband Communication System (Prentice Hall Communications Engineering and Emerging Technologies Series, 2005).

]. Our architecture is also compatible with such modulation formats. As shown in Fig. 3, a length of standard single mode fiber (SSMF) can be added at the output of the NOLM. The pulse position can be controlled by tuning the output wavelength of ECL2, according to the linear relationship between time delay and wavelength difference. Therefore, PPM in electrical domain can be achieved at the output of the PD. Note that the time resolution is determined by the wavelength tuning resolution of ECL2, which is typically 1 pm. In order to make the setup more compact, a specially designed chirped fiber Bragg grating with the required dispersion value can be used to replace the SSMF. Since XPM arising in the HNLF has an ultrafast response time, the reconfiguration time of the UWB pulse generator is mainly determined by the PC, OTDL and the optical switches.

In fact, the proposed approach is able to produce doublet pulses with different polarity simultaneously by simply adding a circulator at the reflection port of the NOLM [21

21. H. Huang, K. Xu, J. Q. Li, J. Wu, X. B. Hong, and J. T. Lin, “UWB pulse generation and distribution using NOLM based optical switch,” J. Lightwave Technol. 26(15), 2635–2640 (2008). [CrossRef]

]. When a doublet pulse is formed at the output of the NOLM, a polarity reversed pulse is also formed at the reflection port due to the power conservation of the probe. This feature makes the UWB generator more flexible than the one based on the nonlinear transmission function of MZM [20

20. Q. Wang and J. Yao, “UWB doublet generation using nonlinearly biased electro-optic intensity modulator,” Electron. Lett. 42(22), 1304–1305 (2006). [CrossRef]

]. Compared with the NOLM-based UWB pulse generator in [21

21. H. Huang, K. Xu, J. Q. Li, J. Wu, X. B. Hong, and J. T. Lin, “UWB pulse generation and distribution using NOLM based optical switch,” J. Lightwave Technol. 26(15), 2635–2640 (2008). [CrossRef]

], we only need 2 laser sources for doublet pair generation. Moreover, the UWB pulses are carried by single wavelength, leading to a better tolerance to fiber dispersion. The proposed UWB pulse generator also has the potential for on-chip integration (e.g., in SOI) by integrating discrete components such as a filter [31

31. M. S. Rasras, D. M. Gill, S. S. Patel, K.-Y. Tu, Y.-K. Chen, A. E. White, A. T. S. Pomerene, D. N. Carothers, M. J. Grove, D. K. Sparacin, J. Michel, M. A. Beals, and L. C. Kimerling, “Demonstration of a fourth-order pole-zero optical filter integrated using CMOS processes,” J. Lightwave Technol. 25(1), 87–92 (2007). [CrossRef]

], coupler, PC [32

32. C. Pu, L. Y. Lin, E. L. Goldstein, N. J. Frigo, and R. W. Tkach, “Micromachined integrated optical polarization-state rotator,” IEEE Photon. Technol. Lett. 12(10), 1358–1360 (2000). [CrossRef]

], and OTDL [29

29. S. Khan, M. A. Baghban, and S. Fathpour, “Electronically tunable silicon photonic delay lines,” Opt. Express 19(12), 11780–11785 (2011). [CrossRef] [PubMed]

] with a length of highly nonlinear waveguide in a single chip. Note that silicon-based Sagnac interferometeric structures have also been reported [33

33. S. Clemmen, K. Phan Huy, W. Bogaerts, R. G. Baets, P. Emplit, and S. Massar, “Continuous wave photon pair generation in silicon-on-insulator waveguides and ring resonators,” Opt. Express 17(19), 16558–16570 (2009). [CrossRef] [PubMed]

]. This will lead to further advantages such as stability, small size, high power efficiency, and better tuning characteristics.

4. Summary

We have proposed a reconfigurable UWB pulse generator based on the pulse shaping capabilities of a NOLM combined with differential detection. The generation of UWB monocycle, doublet, and FCC-complaint triplet with inverted polarity has been experimentally demonstrated. Furthermore, we have shown that our proposed scheme can be easily applied to various modulation formats such as OOK, PSM, BPM, and PPM.

Acknowledgments

This work was supported by the National Basic Research Program of China (973 Program: 2010CB328302), the 863 High Technology Plan (2012AA011301), the National Natural Science Foundation of China (61275069), and the Natural Science and Engineering Research Council of Canada (NSERC) via the CREATE program in Next-Generation Optical Networks.

References and links

1.

D. Porcino, P. Research, and W. Hirt, “Ultra-wideband radio technology: potential and challenges ahead,” IEEE Commun. Mag. 41(7), 66–74 (2003). [CrossRef]

2.

Federal Communications Commission, “Revision of part 15 of the commission's rules regarding ultra-wideband transmission systems,” Tech. Rep. ET- Docket 98–153, FCC02–48, (2002).

3.

Q. Wang, F. Zeng, S. Blais, and J. Yao, “Optical ultrawideband monocycle pulse generation based on cross-gain modulation in a semiconductor optical amplifier,” Opt. Lett. 31(21), 3083–3085 (2006). [CrossRef] [PubMed]

4.

J. Dong, X. Zhang, J. Xu, D. Huang, S. Fu, and P. Shum, “Ultrawideband monocycle generation using cross-phase modulation in a semiconductor optical amplifier,” Opt. Lett. 32(10), 1223–1225 (2007). [CrossRef] [PubMed]

5.

F. Wang, J. Dong, E. Xu, and X. Zhang, “All-optical UWB generation and modulation using SOA-XPM effect and DWDM-based multi-channel frequency discrimination,” Opt. Express 18(24), 24588–24594 (2010). [CrossRef] [PubMed]

6.

H. Y. Jiang, L. S. Yan, J. Ye, W. Pan, B. Luo, Z. Y. Chen, X. H. Zou, and X. S. Yao, “Photonic generation of impulse ultrawideband signals with switchable shapes and polarities based on frequency-to-time mapping,” Opt. Lett. 37(24), 5052–5054 (2012). [CrossRef] [PubMed]

7.

C. Wang, F. Zeng, and J. Yao, “All-fiber ultrawideband pulse generation based on spectral shaping and dispersion-induced frequency-to-time conversion,” IEEE Photon. Technol. Lett. 19(3), 137–139 (2007). [CrossRef]

8.

M. Abtahi, J. Magné, M. Mirshafiei, L. A. Rusch, and S. LaRochelle, “Generation of power-efficient FCC-complaint UWB waveforms using FBGs: analysis and Experiment,” J. Lightwave Technol. 26(5), 628–635 (2008). [CrossRef]

9.

M. Abtahi, M. Mirshafiei, J. Magné, L. A. Rusch, and S. LaRochelle, “Ultra-wideband waveform generator based on optical pulse-shaping and FBG Tuning,” IEEE Photon. Technol. Lett. 20(2), 135–137 (2008). [CrossRef]

10.

X. Feng, Z. Li, B. O. Guan, C. Lu, H. Y. Tam, and P. K. A. Wai, “Switchable UWB pulse generation using a polarization maintaining fiber Bragg grating as frequency discriminator,” Opt. Express 18(4), 3643–3648 (2010). [CrossRef] [PubMed]

11.

F. Zeng and J. Yao, “Ultrawideband signal generation using a high-speed electrooptic phase modulator and an FBG-based frequency discriminator,” IEEE Photon. Technol. Lett. 18(19), 2062–2064 (2006). [CrossRef]

12.

S. Wang, H. Chen, M. Xin, M. Chen, and S. Xie, “Optical ultra-wide-band pulse bipolar and shape modulation based on a symmetric PM-IM conversion architecture,” Opt. Lett. 34(20), 3092–3094 (2009). [CrossRef] [PubMed]

13.

E. Zhou, X. Xu, K. Lui, and K. K. Wong, “A Power-Efficient Ultra-wideband Pulse Generator Based on Multiple PM-IM Conversions,” IEEE Photon. Technol. Lett. 22(14), 1063–1065 (2010). [CrossRef]

14.

Q. Wang and J. Yao, “Switchable optical UWB monocycle and doublet generation using a reconfigurable photonic microwave delay-line filter,” Opt. Express 15(22), 14667–14672 (2007). [CrossRef] [PubMed]

15.

S. Pan and J. Yao, “Switchable UWB pulse generation using a phase modulator and a reconfigurable asymmetric Mach-Zehnder interferometer,” Opt. Lett. 34(2), 160–162 (2009). [CrossRef] [PubMed]

16.

M. Bolea, J. Mora, B. Ortega, and J. Capmany, “Optical UWB pulse generator using an N tap microwave photonic filter and phase inversion adaptable to different pulse modulation formats,” Opt. Express 17(7), 5023–5032 (2009). [CrossRef] [PubMed]

17.

V. Torres-Company, K. Prince, and I. T. Monroy, “Fiber transmission and generation of ultrawideband pulses by direct current modulation of semiconductor lasers and chirp-to-intensity conversion,” Opt. Lett. 33(3), 222–224 (2008). [CrossRef] [PubMed]

18.

H. Lv, Y. Yu, T. Shu, D. Huang, S. Jiang, and L. P. Barry, “Photonic generation of ultra-wideband signals by direct current modulation on SOA section of an SOA-integrated SGDBR laser,” Opt. Express 18(7), 7219–7227 (2010). [CrossRef] [PubMed]

19.

J. Wang, Q. Sun, J. Sun, and W. Zhang, “All-optical UWB pulse generation using sum-frequency generation in a PPLN waveguide,” Opt. Express 17(5), 3521–3530 (2009). [CrossRef] [PubMed]

20.

Q. Wang and J. Yao, “UWB doublet generation using nonlinearly biased electro-optic intensity modulator,” Electron. Lett. 42(22), 1304–1305 (2006). [CrossRef]

21.

H. Huang, K. Xu, J. Q. Li, J. Wu, X. B. Hong, and J. T. Lin, “UWB pulse generation and distribution using NOLM based optical switch,” J. Lightwave Technol. 26(15), 2635–2640 (2008). [CrossRef]

22.

Y. M. Chang, J. Lee, and J. H. Lee, “Ultrawideband doublet pulse generation based on nonlinear polarization rotation of an elliptically polarized beam and its distribution over a fiber/wireless link,” Opt. Express 18(19), 20072–20085 (2010). [CrossRef] [PubMed]

23.

W. Li, L. X. Wang, W. Hofmann, N. H. Zhu, and D. Bimberg, “Generation of ultra-wideband triplet pulses based on four-wave mixing and phase-to-intensity modulation conversion,” Opt. Express 20(18), 20222–20227 (2012). [CrossRef] [PubMed]

24.

J. Li, B. Kuo, and K. Wong, “Ultra-wideband pulse generation based on cross-gain modulation in fiber optical parametric amplifier,” IEEE Photon. Technol. Lett. 21(4), 212–214 (2009). [CrossRef]

25.

A. Bogoni, M. Scaffardi, P. Ghelfi, and L. Poti, “Nonlinear optical loop mirrors: investigation solution and experimental validation for undesirable counterpropagating effects in all-optical signal processing,” IEEE J. Sel. Top. Quantum Electron. 10(5), 1115–1123 (2004). [CrossRef]

26.

S. Pan and J. Yao, “UWB-over-fiber communications: Modulation and transmission,” J. Lightwave Technol. 28(16), 2445–2455 (2010). [CrossRef]

27.

J. D. Bull, N. A. F. Jaeger, H. Kato, M. Fairburn, A. Reid, and P. Ghanipour, “40 GHz electro-optic polarization modulator for fiber optic communication systems,” Proc. SPIE 5577, 133–143 (2004). [CrossRef]

28.

P. A. Morton, J. Cardenas, J. B. Khurgin, and M. Lipson, “Fast thermal switching of wideband optical delay line with no long-term transient,” IEEE Photon. Technol. Lett. 24(6), 512–514 (2012). [CrossRef]

29.

S. Khan, M. A. Baghban, and S. Fathpour, “Electronically tunable silicon photonic delay lines,” Opt. Express 19(12), 11780–11785 (2011). [CrossRef] [PubMed]

30.

J. H. Reed Christopher, An introduction to Ultra Wideband Communication System (Prentice Hall Communications Engineering and Emerging Technologies Series, 2005).

31.

M. S. Rasras, D. M. Gill, S. S. Patel, K.-Y. Tu, Y.-K. Chen, A. E. White, A. T. S. Pomerene, D. N. Carothers, M. J. Grove, D. K. Sparacin, J. Michel, M. A. Beals, and L. C. Kimerling, “Demonstration of a fourth-order pole-zero optical filter integrated using CMOS processes,” J. Lightwave Technol. 25(1), 87–92 (2007). [CrossRef]

32.

C. Pu, L. Y. Lin, E. L. Goldstein, N. J. Frigo, and R. W. Tkach, “Micromachined integrated optical polarization-state rotator,” IEEE Photon. Technol. Lett. 12(10), 1358–1360 (2000). [CrossRef]

33.

S. Clemmen, K. Phan Huy, W. Bogaerts, R. G. Baets, P. Emplit, and S. Massar, “Continuous wave photon pair generation in silicon-on-insulator waveguides and ring resonators,” Opt. Express 17(19), 16558–16570 (2009). [CrossRef] [PubMed]

OCIS Codes
(060.2330) Fiber optics and optical communications : Fiber optics communications
(070.4340) Fourier optics and signal processing : Nonlinear optical signal processing

ToC Category:
Fiber Optics and Optical Communications

History
Original Manuscript: January 16, 2013
Revised Manuscript: February 26, 2013
Manuscript Accepted: February 27, 2013
Published: March 6, 2013

Citation
Tianye Huang, Songnian Fu, Jia Li, Lawrence R Chen, Ming Tang, Perry Shum, and Deming Liu, "Reconfigurable UWB pulse generator based on pulse shaping in a nonlinear optical loop mirror and differential detection," Opt. Express 21, 6401-6408 (2013)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-5-6401


Sort:  Author  |  Year  |  Journal  |  Reset  

References

  1. D. Porcino, P. Research, and W. Hirt, “Ultra-wideband radio technology: potential and challenges ahead,” IEEE Commun. Mag.41(7), 66–74 (2003). [CrossRef]
  2. Federal Communications Commission, “Revision of part 15 of the commission's rules regarding ultra-wideband transmission systems,” Tech. Rep. ET- Docket 98–153, FCC02–48, (2002).
  3. Q. Wang, F. Zeng, S. Blais, and J. Yao, “Optical ultrawideband monocycle pulse generation based on cross-gain modulation in a semiconductor optical amplifier,” Opt. Lett.31(21), 3083–3085 (2006). [CrossRef] [PubMed]
  4. J. Dong, X. Zhang, J. Xu, D. Huang, S. Fu, and P. Shum, “Ultrawideband monocycle generation using cross-phase modulation in a semiconductor optical amplifier,” Opt. Lett.32(10), 1223–1225 (2007). [CrossRef] [PubMed]
  5. F. Wang, J. Dong, E. Xu, and X. Zhang, “All-optical UWB generation and modulation using SOA-XPM effect and DWDM-based multi-channel frequency discrimination,” Opt. Express18(24), 24588–24594 (2010). [CrossRef] [PubMed]
  6. H. Y. Jiang, L. S. Yan, J. Ye, W. Pan, B. Luo, Z. Y. Chen, X. H. Zou, and X. S. Yao, “Photonic generation of impulse ultrawideband signals with switchable shapes and polarities based on frequency-to-time mapping,” Opt. Lett.37(24), 5052–5054 (2012). [CrossRef] [PubMed]
  7. C. Wang, F. Zeng, and J. Yao, “All-fiber ultrawideband pulse generation based on spectral shaping and dispersion-induced frequency-to-time conversion,” IEEE Photon. Technol. Lett.19(3), 137–139 (2007). [CrossRef]
  8. M. Abtahi, J. Magné, M. Mirshafiei, L. A. Rusch, and S. LaRochelle, “Generation of power-efficient FCC-complaint UWB waveforms using FBGs: analysis and Experiment,” J. Lightwave Technol.26(5), 628–635 (2008). [CrossRef]
  9. M. Abtahi, M. Mirshafiei, J. Magné, L. A. Rusch, and S. LaRochelle, “Ultra-wideband waveform generator based on optical pulse-shaping and FBG Tuning,” IEEE Photon. Technol. Lett.20(2), 135–137 (2008). [CrossRef]
  10. X. Feng, Z. Li, B. O. Guan, C. Lu, H. Y. Tam, and P. K. A. Wai, “Switchable UWB pulse generation using a polarization maintaining fiber Bragg grating as frequency discriminator,” Opt. Express18(4), 3643–3648 (2010). [CrossRef] [PubMed]
  11. F. Zeng and J. Yao, “Ultrawideband signal generation using a high-speed electrooptic phase modulator and an FBG-based frequency discriminator,” IEEE Photon. Technol. Lett.18(19), 2062–2064 (2006). [CrossRef]
  12. S. Wang, H. Chen, M. Xin, M. Chen, and S. Xie, “Optical ultra-wide-band pulse bipolar and shape modulation based on a symmetric PM-IM conversion architecture,” Opt. Lett.34(20), 3092–3094 (2009). [CrossRef] [PubMed]
  13. E. Zhou, X. Xu, K. Lui, and K. K. Wong, “A Power-Efficient Ultra-wideband Pulse Generator Based on Multiple PM-IM Conversions,” IEEE Photon. Technol. Lett.22(14), 1063–1065 (2010). [CrossRef]
  14. Q. Wang and J. Yao, “Switchable optical UWB monocycle and doublet generation using a reconfigurable photonic microwave delay-line filter,” Opt. Express15(22), 14667–14672 (2007). [CrossRef] [PubMed]
  15. S. Pan and J. Yao, “Switchable UWB pulse generation using a phase modulator and a reconfigurable asymmetric Mach-Zehnder interferometer,” Opt. Lett.34(2), 160–162 (2009). [CrossRef] [PubMed]
  16. M. Bolea, J. Mora, B. Ortega, and J. Capmany, “Optical UWB pulse generator using an N tap microwave photonic filter and phase inversion adaptable to different pulse modulation formats,” Opt. Express17(7), 5023–5032 (2009). [CrossRef] [PubMed]
  17. V. Torres-Company, K. Prince, and I. T. Monroy, “Fiber transmission and generation of ultrawideband pulses by direct current modulation of semiconductor lasers and chirp-to-intensity conversion,” Opt. Lett.33(3), 222–224 (2008). [CrossRef] [PubMed]
  18. H. Lv, Y. Yu, T. Shu, D. Huang, S. Jiang, and L. P. Barry, “Photonic generation of ultra-wideband signals by direct current modulation on SOA section of an SOA-integrated SGDBR laser,” Opt. Express18(7), 7219–7227 (2010). [CrossRef] [PubMed]
  19. J. Wang, Q. Sun, J. Sun, and W. Zhang, “All-optical UWB pulse generation using sum-frequency generation in a PPLN waveguide,” Opt. Express17(5), 3521–3530 (2009). [CrossRef] [PubMed]
  20. Q. Wang and J. Yao, “UWB doublet generation using nonlinearly biased electro-optic intensity modulator,” Electron. Lett.42(22), 1304–1305 (2006). [CrossRef]
  21. H. Huang, K. Xu, J. Q. Li, J. Wu, X. B. Hong, and J. T. Lin, “UWB pulse generation and distribution using NOLM based optical switch,” J. Lightwave Technol.26(15), 2635–2640 (2008). [CrossRef]
  22. Y. M. Chang, J. Lee, and J. H. Lee, “Ultrawideband doublet pulse generation based on nonlinear polarization rotation of an elliptically polarized beam and its distribution over a fiber/wireless link,” Opt. Express18(19), 20072–20085 (2010). [CrossRef] [PubMed]
  23. W. Li, L. X. Wang, W. Hofmann, N. H. Zhu, and D. Bimberg, “Generation of ultra-wideband triplet pulses based on four-wave mixing and phase-to-intensity modulation conversion,” Opt. Express20(18), 20222–20227 (2012). [CrossRef] [PubMed]
  24. J. Li, B. Kuo, and K. Wong, “Ultra-wideband pulse generation based on cross-gain modulation in fiber optical parametric amplifier,” IEEE Photon. Technol. Lett.21(4), 212–214 (2009). [CrossRef]
  25. A. Bogoni, M. Scaffardi, P. Ghelfi, and L. Poti, “Nonlinear optical loop mirrors: investigation solution and experimental validation for undesirable counterpropagating effects in all-optical signal processing,” IEEE J. Sel. Top. Quantum Electron.10(5), 1115–1123 (2004). [CrossRef]
  26. S. Pan and J. Yao, “UWB-over-fiber communications: Modulation and transmission,” J. Lightwave Technol.28(16), 2445–2455 (2010). [CrossRef]
  27. J. D. Bull, N. A. F. Jaeger, H. Kato, M. Fairburn, A. Reid, and P. Ghanipour, “40 GHz electro-optic polarization modulator for fiber optic communication systems,” Proc. SPIE5577, 133–143 (2004). [CrossRef]
  28. P. A. Morton, J. Cardenas, J. B. Khurgin, and M. Lipson, “Fast thermal switching of wideband optical delay line with no long-term transient,” IEEE Photon. Technol. Lett.24(6), 512–514 (2012). [CrossRef]
  29. S. Khan, M. A. Baghban, and S. Fathpour, “Electronically tunable silicon photonic delay lines,” Opt. Express19(12), 11780–11785 (2011). [CrossRef] [PubMed]
  30. J. H. Reed Christopher, An introduction to Ultra Wideband Communication System (Prentice Hall Communications Engineering and Emerging Technologies Series, 2005).
  31. M. S. Rasras, D. M. Gill, S. S. Patel, K.-Y. Tu, Y.-K. Chen, A. E. White, A. T. S. Pomerene, D. N. Carothers, M. J. Grove, D. K. Sparacin, J. Michel, M. A. Beals, and L. C. Kimerling, “Demonstration of a fourth-order pole-zero optical filter integrated using CMOS processes,” J. Lightwave Technol.25(1), 87–92 (2007). [CrossRef]
  32. C. Pu, L. Y. Lin, E. L. Goldstein, N. J. Frigo, and R. W. Tkach, “Micromachined integrated optical polarization-state rotator,” IEEE Photon. Technol. Lett.12(10), 1358–1360 (2000). [CrossRef]
  33. S. Clemmen, K. Phan Huy, W. Bogaerts, R. G. Baets, P. Emplit, and S. Massar, “Continuous wave photon pair generation in silicon-on-insulator waveguides and ring resonators,” Opt. Express17(19), 16558–16570 (2009). [CrossRef] [PubMed]

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.


« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited