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Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 19, Iss. 4 — Feb. 14, 2011
  • pp: 2952–2958
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Bit-rate variable DPSK demodulation based on cascaded four-wave mixing

Yongheng Dai and Chester Shu  »View Author Affiliations


Optics Express, Vol. 19, Issue 4, pp. 2952-2958 (2011)
http://dx.doi.org/10.1364/OE.19.002952


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Abstract

We report a demodulator for DPSK signals at variable bit rates based on cascaded four-wave mixing (FWM). The demodulation utilizes two FWM processes in a photonic crystal fiber (PCF) with in-between dispersion in a chirped fiber Bragg grating (CFBG). The first FWM generates a wavelength-tunable idler carrying phase information of the signal. A tunable optical delay between the signal and the idler is then introduced by dispersion. The signal, the idler, and the pump are reflected by the CFBG with a reflectance of 99% back to the PCF to initiate the second FWM process. In the second FWM, the phase relationship between the signal and the one-bit-delayed idler determines an amplification or attenuation of the idler, converting phase modulation to intensity modulation. Error-free demodulations have been successfully demonstrated for both NRZ and RZ-DPSK signals at 5 and 10 Gb/s.

© 2011 OSA

1. Introduction

Differential phase-shift-keying (DPSK) data signal exhibits remarkable transmission performance owing to its high tolerance to nonlinear impairments in optical fibers. For direct-detection of DPSK signal, a demodulator is required to convert the phase modulation to intensity modulation before the signal is fed to a balanced or a single-ended detector. Balanced detection grants DPSK format a ~3-dB lower requirement on optical signal-to-noise ratio (OSNR) compared to amplitude shift-keying format at a given bit-error rate (BER), while single-ended detection of DPSK is favored for its simplicity and low cost. DPSK demodulator is also useful in generating optical duobinary (DB) format [1

1. A. H. Gnauck, X. Liu, S. Chandrasekhar, and X. Wei, “Optical duobinary format from demodulation of DPSK using athermal delay interferometer,” IEEE Photon. Technol. Lett. 18(4), 637–639 (2006). [CrossRef]

], bypassing the bandwidth limitation of electronic devices. The demodulation of DSPK signals has been achieved by different approaches. Examples include the use of a delay interferometer (DI) based on fiber [2

2. E. A. Swanson, J. C. Livas, and R. S. Bondurant, “High sensitivity optically preamplified direct detection DPSK receiver with active delay-line stabilization,” IEEE Photon. Technol. Lett. 6(2), 263–265 (1994). [CrossRef]

] or silicon-on-insulator (SOI) [3

3. K. Voigt, L. Zimmermann, G. Winzer, T. Mitze, J. Bruns, K. Petermann, B. Hüttl, and C. Schubert, “Performance of 40-Gb/s DPSK demodulator in SOI-technology,” IEEE Photon. Technol. Lett. 20(8), 614–616 (2008). [CrossRef]

], a birefringent fiber loop [4

4. C. W. Chow and H. K. Tsang, “Polarization-independent DPSK demodulation using a birefringent fiber loop,” IEEE Photon. Technol. Lett. 17(6), 1313–1315 (2005). [CrossRef]

], a fiber Bragg grating (FBG) [5

5. T. Y. Kim, M. Hanawa, S. J. Kim, S. Hann, Y. H. Kim, W. T. Han, and C. S. Park, “Optical DPSK demodulator based on pi-phase-shifted fiber Bragg grating with an optically tunable phase shifter,” IEEE Photon. Technol. Lett. 18(17), 1834–1836 (2006). [CrossRef]

], a stimulated-Brillouin-scattering-based optical filter [6

6. L. Yi, Y. Jaouën, W. Hu, J. Zhou, Y. Su, and E. Pincemin, “Simultaneous demodulation and slow light of differential phase-shift keying signals using stimulated-Brillouin-scattering-based optical filtering in fiber,” Opt. Lett. 32(21), 3182–3184 (2007). [CrossRef] [PubMed]

] and a silicon microring resonator [7

7. L. Xu, C. Li, C. Wong, and H. K. Tsang, “Optical differential-phase-shift-keying demodulation using a silicon microring resonator,” IEEE Photon. Technol. Lett. 21(5), 295–297 (2009). [CrossRef]

]. Among them, DI is the most commonly used structure.

For a conventional DI, the delay is usually fixed for DPSK demodulation at a given bit-rate. However, DI with a tunable delay is useful for various applications. It allows DPSK demodulation at variable bit-rates to meet the need for dynamic bandwidth allocation. Another scenario is in the optimization of delay time to increase the chromatic dispersion tolerance of the system [8

8. Y. K. Lizé, L. Christen, X. Wu, J.-Y. Yang, S. Nuccio, T. Wu, A. E. Willner, and R. Kashyap, “Free spectral range optimization of return-to-zero differential phase shift keyed demodulation in the presence of chromatic dispersion,” Opt. Express 15(11), 6817–6822 (2007). [CrossRef] [PubMed]

]. In addition, an optically time-division-multiplexed (OTDM) DPSK data stream can use a delay-tunable demodulator to perform multibit delay demodulation, where a fine tuning of the delay time is also required to control the detrimental bit-delay mismatch [9

9. Y. K. Lizé, L. Christen, M. Nazarathy, Y. Atzmon, S. Nuccio, P. Saghari, R. Gomma, J.-Y. Yang, R. Kashyap, A. E. Willner, and L. Paraschis, “Tolerances and receiver sensitivity penalties of multibit delay differential-phase shift-keying demodulation,” IEEE Photon. Technol. Lett. 19(23), 1874–1876 (2007). [CrossRef]

]. Apart from DPSK demodulation, cascaded DIs with different delays can be used to perform real-time optical fast Fourier transform to demultiplex an optical OFDM signal [10

10. D. Hillerkuss, M. Winter, M. Teschke, A. Marculescu, J. Li, G. Sigurdsson, K. Worms, S. Ben Ezra, N. Narkiss, W. Freude, and J. Leuthold, “Simple all-optical FFT scheme enabling Tbit/s real-time signal processing,” Opt. Express 18(9), 9324–9340 (2010). [CrossRef] [PubMed]

].

Previously, DI with a tunable delay from 0 to 200 ps has been demonstrated using a tunable differential-group-delay element [11

11. L. Christen, Y. Lizé, S. Nuccio, A. E. Willner, and L. Paraschis, “Variable rate, multi-format receiver design for 10 to 40 Gb/s DPSK and OOK formats,” Opt. Express 16(6), 3828–3833 (2008). [CrossRef] [PubMed]

]. For a larger tunable range, the combination of wavelength conversion and dispersion is ready to be used. Based on this method, we have recently demonstrated DPSK demodulation with widely continuous bit-rate tunability using a delay asymmetric nonlinear loop mirror (DANLM) [12

12. M. P. Fok and C. Shu, “Delay-asymmetric nonlinear loop mirror for DPSK demodulation,” Opt. Lett. 33(23), 2845–2847 (2008). [CrossRef] [PubMed]

,13

13. Y. Dai, C. Shu, and M. P. Fok, “Dual-pumped delay-asymmetric nonlinear loop mirror for DPSK demodulation at widely tunable bit rates,” in Proceedings of OptoElectronics and Communications Conference (IEEE 2009), paper FE6.

]. In the DANLM, the wavelength conversion is based on four-wave mixing (FWM) in a 64-m photonic crystal fiber (PCF), while a 10-ps/nm dispersion is provided by a 600-m single mode fiber (SMF). The bulkiness of the DANLM can be a concern in some applications. For miniaturization, a silicon waveguide [14

14. Y. Okawachi, M. A. Foster, A. C. Turner, R. Salem, J. S. Levy, M. Lipson, and A. L. Gaeta, “Tunable delays via conversion-dispersion using on-chip four-wave-mixing,” in Proceedings of Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference and Photonic Applications Systems Technologies 2008 Technical Digest (Optical Society of America, Washington, DC, 2008),paper CMBB4.

] can be used to replace the nonlinear PCF, while a chirped FBG (CFBG) offers a means to provide tens of ps/nm dispersion over a short fiber segment. Unfortunately, the CFBG cannot be used in a loop structure since it operates in a reflection manner. To overcome this problem, we propose a straight-line structure that incorporates the CFBG and verify the operation of variable bit-rate demodulation [15

15. Y. Dai, and C. Shu, “Tunable DPSK demodulation using variable optical delay in a straight-line interferometric structure,” in Proceedings of European Conference and Exhibition on Optical Communication (IEEE 2010), paper P1. 13.

]. In this paper, we explain the role of two FWM processes in the structure as similar to phase sensitive amplification based on cascaded FWM. We further demonstrate that in addition to achieving bit-rate variable demodulation, a 0-phase or π-phase shift can be introduced to switch the demodulated signal into an optical DB or alternate mark inversion (AMI) format. The precise phase control may also be useful for OFDM demultiplexing [10

10. D. Hillerkuss, M. Winter, M. Teschke, A. Marculescu, J. Li, G. Sigurdsson, K. Worms, S. Ben Ezra, N. Narkiss, W. Freude, and J. Leuthold, “Simple all-optical FFT scheme enabling Tbit/s real-time signal processing,” Opt. Express 18(9), 9324–9340 (2010). [CrossRef] [PubMed]

]. NRZ/RZ-DB/AMI signals at 10 Gb/s and 5 Gb/s are successfully generated and the performances are characterized by BER measurements.

2. Operation principle

Figure 1
Fig. 1 Principle of DPSK demodulation based on cascaded FWM. S: signal; P: pump; I: idler.
illustrates the scheme of DPSK demodulation based on cascaded FWM. The principle is similar to that of phase sensitive amplification [16

16. K. Croussore and G. Li, “Phase regeneration of NRZ-DPSK signals based on symmetric-pump phase sensitive amplification,” IEEE Photon. Technol. Lett. 19(11), 864–866 (2007). [CrossRef]

]. The first FWM generates idler 1 which is then automatically phase-locked to the signal and the pump. The phase of idler 1 is determined by the signal phase and pump phase asϕI1(t)=2ϕpϕs(t). Since the pump is CW with a linewidth of ~100 kHz (Agilent HP 8168F), it is not necessary to consider its phase variation over time compared to the phase-modulated signal. After a delay time T is introduced between the signal and idler 1, the second FWM is initiated to amplify or to attenuate the idler through the interference between idler 1 and idler 2. The amplification or attenuation is determined by the phase difference between the signal, the pump, and idler 1 in the second FWM,
Δϕ=2ϕpϕs(t)ϕI1(tT)=ϕs(tT)ϕs(t)
where the 0-phase and π-phase difference correspond to amplification and attenuation of idler 1, respectively.

The delay time T is generated based on a combination of wavelength conversion and dispersion. For a given dispersion coefficient, T is determined by the wavelength shift between the signal and idler 1, which is adjustable by tuning the pump wavelength. If T is set to one bit period of a DPSK signal, the idler power after the cascaded FWM processes will depend on the phase difference between two neighboring bits in the data sequence, converting the phase modulation to intensity modulation. In our setup, the delay time T is introduced in a CFBG with a 20-ps/nm dispersion. By tuning the pump wavelength of FWM, one-bit delay can always be generated for DPSK signals at variable bit-rates to achieve the demodulation. Moreover, additional 0-phase or π-phase shift can be introduced between the signal and idler 1, thus switching the output between DB and AMI formats that appear respectively at the constructive and destructive ports of a conventional fixed-delay DI. The wavelength resolution of our CW pump is 0.001 nm, corresponding to a minimum phase shift of ~0.05π for a 20-ps/nm dispersion. To introduce a π-phase shift, the pump wavelength should be shifted by 0.02 nm to yield a 0.04-nm shift of the idler wavelength.

3. Experimental results and discussion

Figure 2
Fig. 2 Setup of the bit-rate variable demodulator. TL: tunable laser; PM: phase modulator; MZM: Mach-Zehnder modulator; EDFA: erbium-doped fiber amplifier; PC: polarization controller; BPF: optical bandpass filter; PCF: photonic crystal fiber; CFBG: chirped fiber Bragg grating; BER: bit error rate.
shows the experimental setup of our bit-rate variable DPSK demodulator. The FWM-based wavelength conversion is performed in a 41-m PCF. The PCF is placed between two polarization controllers to overcome polarization change caused by the PCF birefringence. Following the PCF, a CFBG provides a flattened dispersion of 20 ps/nm and a reflectance of 99% over the range of 1535 to 1565 nm. An optical circulator and a bandpass filter with a 3-dB bandwidth of 0.6 nm are used to extract the idler output.

The DPSK transmitter consists of a tunable laser, a phase modulator driven by a PRBS (231-1), and a Mach-Zehnder modulator (MZM) driven by a clock. When NRZ-DPSK signal is used as the input, the MZM is turned off. The DPSK signal is combined with a wavelength tunable CW pump before they are amplified by an EDFA to a total power of ~26 dBm. The first stage of FWM takes place when the signal and the pump propagate through the PCF towards the CFBG. After the reflection from the CFBG, the pump, the signal, and the generated idler 1 will travel through the PCF again in the opposite direction. Owing to the high reflectance of the CFBG, the optical power loss results mainly from the splice between the PCF and the CFBG. The loss is ~2.5 dB in our setup such that the second stage of FWM is still effective. Idler 1 experiences a tunable delay with reference to the signal in the CFBG according to its wavelength, which is controlled by the CW pump wavelength. When the delay is set to one bit period of the corresponding data rate, the phase difference between two neighboring bits of the DPSK signal will determine an amplification or attenuation of idler 1, resulting in DPSK demodulation at variable bit-rates.

To verify the demodulation principle, Fig. 3
Fig. 3 Eye diagrams and optical spectra of the idlers centered at 1555 nm. (a) after the first FWM, (b) behind the CFBG, (c) after the second FWM with 0-phase shift, and (d) after the second FWM with π-phase shift. The measurement positions correspond to points A, B, and C in Fig. 2. Inset: incomplete depletion of idler 1.
shows the eye diagrams and spectra of the idlers obtained from 10-Gb/s RZ-DPSK signal measured at three different positions in the setup, indicated as A, B, and C in Fig. 2. These are the idlers obtained after the first stage of FWM, behind the CFBG, and after the second stage of FWM, respectively. At points A and B, both the eye diagrams and the spectra agree with those of a DPSK signal without demodulation [17

17. P. J. Winzer and R. J. Essiambre, “Advanced modulation formats for high-capacity optical transport networks,” J. Lightwave Technol. 24(12), 4711–4728 (2006). [CrossRef]

], implying that demodulation is achieved neither by a single FWM process nor by the filtering of the CFBG. Only after two stages of FWM, the phase modulation is converted to intensity modulation. By slightly tuning the CW pump wavelength, an additional phase shift of 0 or π can be introduced to generate an output in DB format or AMI format, respectively, as shown in Figs. 3(c) and 3(d).

It is worth mentioning that the splicing loss between the PCF and the CFBG results in a difference of the signal powers in the two stages of FWM, possibly leading to incomplete depletion of idler 1 and hence a degraded extinction ratio (ER) of the demodulated signal, as shown in the inset of Fig. 3. We experimentally find that the ER can be improved by changing the signal-to-pump power ratio to a positive value of ~3 dB, unlike the usual case where the ratio is negative to keep the signal weaker than the pump. With the adjustment, the residual power of bit 0 in idler 1 is reduced, as shown in the other two eye diagrams in Fig. 3. One also notices a finite signal distortion of AMI format compared to DB format. It can be explained by the discrete control of phase shift resulted from discrete wavelength tuning of the pump laser. When the phase shift is aligned to be 0 for the DB format, it may be difficult to tune it exactly to π to generate AMI format. The problem can be mitigated using a smaller dispersion to provide a finer tuning at a given tuning resolution of the pump wavelength.

To demodulate DPSK signals at different bit rates, we tune the wavelength of the CW pump to introduce a proper delay between the signal and idler 1. Figures 4(a)
Fig. 4 FWM spectra in the demodulation of (a) 10 Gb/s and (b) 5 Gb/s signals.
and 4(b) show the experimental FWM spectra in the demodulations of 10-Gb/s and 5-Gb/s signals, respectively. The FWM efficiency, defined as the power ratio of the generated idler to the input signal, is ~-22 dB. For 10-Gb/s signal, the wavelength shift between the signal and idler is 5 nm, thus providing a 100-ps delay with the 20-ps/nm dispersion in the CFBG. For 5-Gb/s signal, a 10-nm wavelength shift provides a 200-ps delay.

For NRZ-DPSK signals, the demodulated signals are shown in Fig. 5
Fig. 5 Demodulated NRZ-DPSK signals. Bit-rate variable demodulator: (a) 10-Gb/s DB, (b) 10-Gb/s AMI, (c) 5-Gb/s DB, (d) 5-Gb/s AMI; Standard DI: (e) 10-Gb/s DB, (f) 10-Gb/s AMI; and (g) BER measurement of the demodulated signals.
, including 10-Gb/s DB, 10-Gb/s AMI, 5-Gb/s DB and 5-Gb/s AMI as indicated in (a)-(d). For all cases, clear eyes are obtained, demonstrating the capability of our demodulator to operate at widely variable bit rates. For comparison, the eye diagrams of demodulated 10-Gb/s NRZ-DPSK signals obtained from a standard fiber-based Mach-Zehnder DI [18

18. A. H. Gnauck and P. J. Winzer, “Optical phase-shift-keyed transmission,” J. Lightwave Technol. 23(1), 115–130 (2005). [CrossRef]

] with a fixed-delay of ~100 ps are also shown in Figs. 5(e) and 5(f). The BERs of the six signals measured with a 10-GHz single-ended photodetector are shown in Fig. 5(g). In general, the NRZ-AMI format has a higher receiver sensitivity compared to NRZ-DB format due to a difference in the pulse shape caused by transient phase modulation at the rising edge and falling edge. For 10-Gb/s NRZ-DPSK signal, the standard DI exhibits 2.5 and 2.8 dB improvement in the receiver sensitivities over our bit-rate variable demodulator for DB and AMI formats, respectively. The difference can be explained by the occurrence of ASE noise in the EDFA and signal degradation in FWM in the bit-rate variable scheme. The additional 0.3 dB degradation of AMI may result from the discrete phase tuning as mentioned above. The results of RZ-DPSK signals with a duty cycle of ~50% are also shown in Figs. 6(a)
Fig. 6 Demodulated RZ-DPSK signals. Bit-rate variable demodulator: (a) 10-Gb/s DB, (b) 10-Gb/s AMI, (c) 5-Gb/s DB, (d) 5-Gb/s AMI; Standard DI: (e) 10-Gb/s DB, (f) 10-Gb/s AMI; and (g) BER measurement of the demodulated signals.
- 6(g). For the standard DI, DB and AMI formats show almost identical receiver sensitivities. For variable bit-rate demodulation, however, RZ-AMI has a smaller tolerance to discrete phase tuning compared to NRZ-AMI, resulting in an additional degradation of 0.7 dB with reference to RZ-DB.

For further miniaturization of our setup, integrated devices can be used to replace the fiber components. A chirped vertical grating based on SOI technology has been demonstrated in [19

19. D. T. H. Tan, K. Ikeda, R. E. Saperstein, B. Slutsky, and Y. Fainman, “Chip-scale dispersion engineering using chirped vertical gratings,” Opt. Lett. 33(24), 3013–3015 (2008). [CrossRef] [PubMed]

], providing a 7.0 × 105 ps/nm/km dispersion with an acceptable level of reflectance. Combining with a silicon nano-waveguide [14

14. Y. Okawachi, M. A. Foster, A. C. Turner, R. Salem, J. S. Levy, M. Lipson, and A. L. Gaeta, “Tunable delays via conversion-dispersion using on-chip four-wave-mixing,” in Proceedings of Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference and Photonic Applications Systems Technologies 2008 Technical Digest (Optical Society of America, Washington, DC, 2008),paper CMBB4.

], both the functionalities of wavelength conversion and dispersion can be possibly integrated into a tiny silicon chip.

4. Conclusion

A bit-rate variable DPSK demodulator is demonstrated in a straight-line structure. The setup exploits a process similar to phase sensitive amplification using cascaded FWM in a 41-m PCF separated by a tunable optical delay. The delay is obtained from wavelength conversion followed by dispersion in a chirped fiber Bragg grating. By tuning the delay, NRZ-DPSK and RZ-DPSK signals at 10 Gb/s and 5 Gb/s are demodulated with error-free performances. The switching between DB and AMI formats is also achieved by the fine control of the delay.

Acknowledgement

This work is supported by the Research Grants Council of Hong Kong (Projects CUHK 415907, 416808, 416509).

References and links

1.

A. H. Gnauck, X. Liu, S. Chandrasekhar, and X. Wei, “Optical duobinary format from demodulation of DPSK using athermal delay interferometer,” IEEE Photon. Technol. Lett. 18(4), 637–639 (2006). [CrossRef]

2.

E. A. Swanson, J. C. Livas, and R. S. Bondurant, “High sensitivity optically preamplified direct detection DPSK receiver with active delay-line stabilization,” IEEE Photon. Technol. Lett. 6(2), 263–265 (1994). [CrossRef]

3.

K. Voigt, L. Zimmermann, G. Winzer, T. Mitze, J. Bruns, K. Petermann, B. Hüttl, and C. Schubert, “Performance of 40-Gb/s DPSK demodulator in SOI-technology,” IEEE Photon. Technol. Lett. 20(8), 614–616 (2008). [CrossRef]

4.

C. W. Chow and H. K. Tsang, “Polarization-independent DPSK demodulation using a birefringent fiber loop,” IEEE Photon. Technol. Lett. 17(6), 1313–1315 (2005). [CrossRef]

5.

T. Y. Kim, M. Hanawa, S. J. Kim, S. Hann, Y. H. Kim, W. T. Han, and C. S. Park, “Optical DPSK demodulator based on pi-phase-shifted fiber Bragg grating with an optically tunable phase shifter,” IEEE Photon. Technol. Lett. 18(17), 1834–1836 (2006). [CrossRef]

6.

L. Yi, Y. Jaouën, W. Hu, J. Zhou, Y. Su, and E. Pincemin, “Simultaneous demodulation and slow light of differential phase-shift keying signals using stimulated-Brillouin-scattering-based optical filtering in fiber,” Opt. Lett. 32(21), 3182–3184 (2007). [CrossRef] [PubMed]

7.

L. Xu, C. Li, C. Wong, and H. K. Tsang, “Optical differential-phase-shift-keying demodulation using a silicon microring resonator,” IEEE Photon. Technol. Lett. 21(5), 295–297 (2009). [CrossRef]

8.

Y. K. Lizé, L. Christen, X. Wu, J.-Y. Yang, S. Nuccio, T. Wu, A. E. Willner, and R. Kashyap, “Free spectral range optimization of return-to-zero differential phase shift keyed demodulation in the presence of chromatic dispersion,” Opt. Express 15(11), 6817–6822 (2007). [CrossRef] [PubMed]

9.

Y. K. Lizé, L. Christen, M. Nazarathy, Y. Atzmon, S. Nuccio, P. Saghari, R. Gomma, J.-Y. Yang, R. Kashyap, A. E. Willner, and L. Paraschis, “Tolerances and receiver sensitivity penalties of multibit delay differential-phase shift-keying demodulation,” IEEE Photon. Technol. Lett. 19(23), 1874–1876 (2007). [CrossRef]

10.

D. Hillerkuss, M. Winter, M. Teschke, A. Marculescu, J. Li, G. Sigurdsson, K. Worms, S. Ben Ezra, N. Narkiss, W. Freude, and J. Leuthold, “Simple all-optical FFT scheme enabling Tbit/s real-time signal processing,” Opt. Express 18(9), 9324–9340 (2010). [CrossRef] [PubMed]

11.

L. Christen, Y. Lizé, S. Nuccio, A. E. Willner, and L. Paraschis, “Variable rate, multi-format receiver design for 10 to 40 Gb/s DPSK and OOK formats,” Opt. Express 16(6), 3828–3833 (2008). [CrossRef] [PubMed]

12.

M. P. Fok and C. Shu, “Delay-asymmetric nonlinear loop mirror for DPSK demodulation,” Opt. Lett. 33(23), 2845–2847 (2008). [CrossRef] [PubMed]

13.

Y. Dai, C. Shu, and M. P. Fok, “Dual-pumped delay-asymmetric nonlinear loop mirror for DPSK demodulation at widely tunable bit rates,” in Proceedings of OptoElectronics and Communications Conference (IEEE 2009), paper FE6.

14.

Y. Okawachi, M. A. Foster, A. C. Turner, R. Salem, J. S. Levy, M. Lipson, and A. L. Gaeta, “Tunable delays via conversion-dispersion using on-chip four-wave-mixing,” in Proceedings of Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference and Photonic Applications Systems Technologies 2008 Technical Digest (Optical Society of America, Washington, DC, 2008),paper CMBB4.

15.

Y. Dai, and C. Shu, “Tunable DPSK demodulation using variable optical delay in a straight-line interferometric structure,” in Proceedings of European Conference and Exhibition on Optical Communication (IEEE 2010), paper P1. 13.

16.

K. Croussore and G. Li, “Phase regeneration of NRZ-DPSK signals based on symmetric-pump phase sensitive amplification,” IEEE Photon. Technol. Lett. 19(11), 864–866 (2007). [CrossRef]

17.

P. J. Winzer and R. J. Essiambre, “Advanced modulation formats for high-capacity optical transport networks,” J. Lightwave Technol. 24(12), 4711–4728 (2006). [CrossRef]

18.

A. H. Gnauck and P. J. Winzer, “Optical phase-shift-keyed transmission,” J. Lightwave Technol. 23(1), 115–130 (2005). [CrossRef]

19.

D. T. H. Tan, K. Ikeda, R. E. Saperstein, B. Slutsky, and Y. Fainman, “Chip-scale dispersion engineering using chirped vertical gratings,” Opt. Lett. 33(24), 3013–3015 (2008). [CrossRef] [PubMed]

OCIS Codes
(060.5060) Fiber optics and optical communications : Phase modulation
(190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing

ToC Category:
Fiber Optics and Optical Communications

History
Original Manuscript: November 23, 2010
Revised Manuscript: December 19, 2010
Manuscript Accepted: December 20, 2010
Published: February 1, 2011

Citation
Yongheng Dai and Chester Shu, "Bit-rate variable DPSK demodulation based on cascaded four-wave mixing," Opt. Express 19, 2952-2958 (2011)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-19-4-2952


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References

  1. A. H. Gnauck, X. Liu, S. Chandrasekhar, and X. Wei, “Optical duobinary format from demodulation of DPSK using athermal delay interferometer,” IEEE Photon. Technol. Lett. 18(4), 637–639 (2006). [CrossRef]
  2. E. A. Swanson, J. C. Livas, and R. S. Bondurant, “High sensitivity optically preamplified direct detection DPSK receiver with active delay-line stabilization,” IEEE Photon. Technol. Lett. 6(2), 263–265 (1994). [CrossRef]
  3. K. Voigt, L. Zimmermann, G. Winzer, T. Mitze, J. Bruns, K. Petermann, B. Hüttl, and C. Schubert, “Performance of 40-Gb/s DPSK demodulator in SOI-technology,” IEEE Photon. Technol. Lett. 20(8), 614–616 (2008). [CrossRef]
  4. C. W. Chow and H. K. Tsang, “Polarization-independent DPSK demodulation using a birefringent fiber loop,” IEEE Photon. Technol. Lett. 17(6), 1313–1315 (2005). [CrossRef]
  5. T. Y. Kim, M. Hanawa, S. J. Kim, S. Hann, Y. H. Kim, W. T. Han, and C. S. Park, “Optical DPSK demodulator based on pi-phase-shifted fiber Bragg grating with an optically tunable phase shifter,” IEEE Photon. Technol. Lett. 18(17), 1834–1836 (2006). [CrossRef]
  6. L. Yi, Y. Jaouën, W. Hu, J. Zhou, Y. Su, and E. Pincemin, “Simultaneous demodulation and slow light of differential phase-shift keying signals using stimulated-Brillouin-scattering-based optical filtering in fiber,” Opt. Lett. 32(21), 3182–3184 (2007). [CrossRef] [PubMed]
  7. L. Xu, C. Li, C. Wong, and H. K. Tsang, “Optical differential-phase-shift-keying demodulation using a silicon microring resonator,” IEEE Photon. Technol. Lett. 21(5), 295–297 (2009). [CrossRef]
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