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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 20, Iss. 10 — May. 7, 2012
  • pp: 11517–11528
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Distortion-free spectrum sliced microwave photonic signal processor: analysis, design and implementation

Liwei Li, Xiaoke Yi, Thomas X. H. Huang, and Robert A. Minasian  »View Author Affiliations


Optics Express, Vol. 20, Issue 10, pp. 11517-11528 (2012)
http://dx.doi.org/10.1364/OE.20.011517


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Abstract

A new switchable microwave photonic filter based on a novel spectrum slicing technique is presented. The processor enables programmable multi-tap generation with general transfer function characteristics and offers tunability, reconfigurabiliy, and switchability. It is based on connecting a dispersion controlled spectrum slicing filter after the modulated bipolar broadband light source, which consequently generates multiple spectrum slices with bipolarity, and compensates dispersion induced RF degradation simultaneously within a single device. A detailed theoretical model for this microwave photonic filter design is presented. Experimental results are presented which verify the model, and demonstrate a 33 bipolar-tap microwave filter with significant reduction of passband attenuations at high frequencies. The RF response improvement of the new microwave photonic filter is investigated, for both an ideal linear group delay line and for the experimental fiber delay line that has second order group delay and the results show that this new structure is effective for RF filters with various free spectral range values and spectrum slice bandwidths. Finally, a switchable bipolar filter that has a square-top bandpass filter response with more than 30 dB stopband attenuation that can be switched on/off via software control is demonstrated.

© 2012 OSA

1. Introduction

Microwave photonic signal processing using optical delay line structures is attractive for processing high speed signals, because it can overcome inherent electronic bottlenecks caused by limited sampling speeds in conventional electrical signal processors. It also offers some significant features such as immunity to electromagnetic interference and large time-bandwidth product [1

1. R. A. Minasian, “Photonic signal processing of microwave signals,” IEEE Trans. Microw. Theory Tech. 54(2), 832–846 (2006). [CrossRef]

, 2

2. J. P. Yao, “Microwave photonics,” J. Lightwave Technol. 27(3), 314–335 (2009). [CrossRef]

].

Microwave photonic filters based on finite impulse response (FIR) are particularly of interest because of their inherent flexibility in realizing filters having arbitrary transfer functions [3

3. J. Capmany, D. Pastor, and B. Ortega, “New and flexible fiber-optic delay-line filters using chirped Bragg gratings and laser arrays,” IEEE Trans. Microw. Theory Tech. 47(7), 1321–1326 (1999). [CrossRef]

6

6. T. X. H. Huang, X. Yi, and R. A. Minasian, “New multiple-tap, general-response, reconfigurable photonic signal processor,” Opt. Express 17(7), 5358–5363 (2009). [CrossRef] [PubMed]

]. A common FIR topology comprises an array of lasers that are modulated and then applied to a linearly chirped fiber Bragg grating (FBG) which forms a discrete time microwave signal processor after photodetection [3

3. J. Capmany, D. Pastor, and B. Ortega, “New and flexible fiber-optic delay-line filters using chirped Bragg gratings and laser arrays,” IEEE Trans. Microw. Theory Tech. 47(7), 1321–1326 (1999). [CrossRef]

]. The use of spectrum slicing of a broadband optical source for the replacement of an optical laser array provides a flexible and scalable solution for realizing multiple taps which is necessary to achieve high resolution signal processing [7

7. J. Capmany, D. Pastor, and B. Ortega, “Fiber optic microwave and millimeter-wave filter with high density sampling and very high sidelobe suppression using sub nanometer optical spectrum slicing,” Electron. Lett. 35(6), 494–496 (1999). [CrossRef]

9

9. B. A. L. Gwandu, W. Zhang, J. A. R. Williams, L. Zhang, and I. Bennion, “Microwave photonic filtering using Gaussian-profiled superstructured fiber Bragg grating and dispersive fiber,” Electron. Lett. 38(22), 1328–1330 (2002). [CrossRef]

]. However, a critical issue with the performance of conventional spectrum sliced microwave photonic filters is that it suffers from significant high frequency degradation. This occurs because of the substantial width of the spectral slice, which results in a broad region of the dispersive medium being illuminated rather than a point. This causes a complex interaction in the response, which creates RF frequency response degradation that occurs in addition to and which can dominate over the well-known carrier suppression effect [10

10. X. Yi and R. A. Minasian, “Dispersion induced RF distortion of spectrum-sliced microwave-photonic filters,” IEEE Trans. Microw. Theory Tech. 54(2), 880–886 (2006). [CrossRef]

]. Although various spectrum slicing techniques have been reported, including Fabry-Perot filters, arrayed waveguide gratings and super-structured FBGs [7

7. J. Capmany, D. Pastor, and B. Ortega, “Fiber optic microwave and millimeter-wave filter with high density sampling and very high sidelobe suppression using sub nanometer optical spectrum slicing,” Electron. Lett. 35(6), 494–496 (1999). [CrossRef]

9

9. B. A. L. Gwandu, W. Zhang, J. A. R. Williams, L. Zhang, and I. Bennion, “Microwave photonic filtering using Gaussian-profiled superstructured fiber Bragg grating and dispersive fiber,” Electron. Lett. 38(22), 1328–1330 (2002). [CrossRef]

], in order for spectrum sliced microwave photonic filters to be used practically, it is essential to obtain effective solutions to eliminate this undesirable RF frequency response degradation.

2. Filter topology

Topology of the new spectrum sliced microwave photonic filter is shown in Fig. 1
Fig. 1 Structure of the microwave photonic processor.
. A broadband light source is intensity modulated by a dual-output EOM, which introduces 180° RF phase difference between the modulated light at its dual output ports. Then the modulated bipolar broadband source is launched into port 1 and port 2 of a device that is called a dispersion controlled spectrum slicing filter, which generates spectrum slices with dispersion controllability after the modulation stage. The light then propagates through a linear time delay element, and is finally detected on a photodetector.

The dispersion controlled spectrum slicing filter has two input ports that are connected to the modulated bipolar broadband optical source, and it has one output port that feeds into the dispersive group delay element. It is required to generate counter-modulated spectrum slices with desired centre wavelengths, bandwidth, attenuation and dispersion management. By programming single port (either port 1 or port2) or both input ports of the slicing filter, positive taps or bipolar taps can be obtained respectively. Since the dispersion value within each slice is set to be the opposite of the dispersive delay element, it consequently results in a flat group delay region within each channel which eliminates the dispersion induced RF distortion. A free-space optical system based on a two-dimensional array of liquid crystal on silicon (LCoS) pixels can be used to implement these functions [14

14. G. Baxter, S. Frisken, D. Abakoumov, H. Zhou, I. Clarke, A. Bartos, and S. Poole, “Highly programmable wavelength selective switch based on liquid crystal on silicon switching elements,” in Optical Fiber Communication Conference and Exposition and The National Fiber Optic Engineers Conference, Technical Digest (CD) (Optical Society of America, 2006), paper OTuF2.

]. The counter-modulated broadband optical light sources enter the two input ports of the system, which are dispersed to the wavelength-dependent columns of the LCoS pixels. By varying the voltage-controlled phase across the vertical and horizontal dimension of the LCoS, the spectral phase and intensity of the optical signals are simultaneously manipulated. In addition, the optical phase pattern enables the achievement of spectral routing or blocking of the optical signals from either one of the two input ports to the output port of the slicing filter, which forms multiple counter-modulated spectrum slices. Consequently, the configuration can realize tunability, reconfigurability, switching, and dispersion induced RF degradation compensation simultaneously in the microwave photonic filters.

3. Filter principle

The modulated bipolar broadband light source is achieved by amplitude modulating a broadband light source via a dual-output EOM, whose modulation envelope can be described as [15

15. C. H. Cox III, Analog Optical Links: Theory and Practice (Cambridge University Press, 2004).

]
s0(t)=cos(π2Vπ(VRFcos(2πfmt)+Vbias+kVπ))
(1)
where Vπis the modulator switching voltage, VRFis the amplitude of the RF signal, fmis the modulation frequency,Vbiasis the bias voltage, which requires Vbias=Vπ/2 for maximum linearity, k is a binary polarity factor, k=0 and k=1for the light from the output port 1 and 2 of the dual-output EOM respectively.

After modulation, the counter-modulated broadband light source propagates through the dispersion controlled spectrum slicing filter, which is followed by a linearly dispersive element that is described byτ(f)=a1f+a0, wherefis the optical frequency, a1represents the group delay slope anda0 is the delay offset. The modulated spectrum slices are created by the slicing filter locating with equal channel spacing (Δf) to maintain a basic time delay of microwave photonic filter, and the FSR of the filter isFSR=1/(a1Δf), which can be controlled by adjusting the spacing between two consecutive spectrum slices .

We consider N taps of bipolar spectrum sliced sources such that each slice has the central optical frequencyfn, and slice amplitudegn(f), where n = 1, 2, …,N. In order to avoid additional degradation in the RF frequency response caused by unbalanced spectrum slice shapes [10

10. X. Yi and R. A. Minasian, “Dispersion induced RF distortion of spectrum-sliced microwave-photonic filters,” IEEE Trans. Microw. Theory Tech. 54(2), 880–886 (2006). [CrossRef]

], we design all the spectrum slices to have identical normalized amplitudeg0(f). Thus the slice amplitude can be expressed asgn(f)=Wng0(ffn), where Wnis the optical power coefficient of the nthspectrum slice.

Figure 2(a)
Fig. 2 Simulated filter response using 33 bipolar rectangular spectrum slices having a width of 72 GHz: (a) without dispersion compensation (b) with dispersion compensation.
shows the simulated baseband-suppressed filter response for 33 bipolar rectangular spectrum slices having a width of 72 GHz that propagate through a delay line having a dispersion of −150 ps/nm, without applying the dispersion compensation function through the slicing filter. The RF degradation increases rapidly with frequency, which significantly limits the filter response. More than 41 dB degradation is observed at the third passband (14.67 GHz). After applying the dispersion compensation function through the dispersion controlled spectrum slicing filter, the performance can be significantly improved as shown in Fig. 2(b). Similar results can also be obtained for baseband microwave photonic filters that have positive taps only.

4. Experimental results and discussion

Experiments were carried out based on the scheme shown in Fig. 1. The broadband source was obtained from an erbium-doped fiber amplifier and after modulation by the dual-output EOM with 20 GHz modulation bandwidth (EOSPACE Inc.) to obtain modulated bipolar signals it was launched into port 1 and port 2 of the dispersion controlled spectrum slicing filter, which was implemented using a commercially-available WaveShaper (Finisar). The device enables multiple programmable slicing filters (minimum bandwidth setting of 10 GHz) within a wavelength range of 1527.4 nm to 1567.5 nm, which determines the largest number of filter coefficients to be realised, given the FSR of the RF filter and the dispersive delay element. Note that there exists a trade off between the maximum achievable group delay slope and the slicing filter bandwidth, where a four-pass configuration can be incorporated to increase the dispersion bandwidth product [16

16. M. A. F. Roelens, S. Frisken, J. A. Bolger, D. Abakoumov, G. Baxter, S. Poole, and B. J. Eggleton, “Dispersion trimming in a reconfigurable wavelength selective switch,” J. Lightwave Technol. 26(1), 73–78 (2008). [CrossRef]

]. A length of optical fiber (Corning MetroCor) was used in the experiment to approximate the linear group delay line and to provide the wideband time delay function for achieving a large number of taps. The group delay of the optical fiber was measured and it showed a dispersion slope factor of 1.9ps/nm2. The average dispersion (d) of the fiber within C-band operation was 150ps/nm, and the corresponding time delay could be quite accurately described using a second order function in terms of optical frequency(f) as τ(f)=b2f2+b1f+b0, whereb2is the quadratic coefficient which is known as fiber second order group delay factor, b1 is the group delay linear coefficient, and b0 is the fiber group delay offset.

A constant filter time delay step (Δt) can be obtained to avoid RF response distortion by adjusting the spacing between two consecutive spectrum slices. HereΔtis given byΔt=τ(fn+1)τ(fn), wherefn+1and fnrepresents the central optical frequency of the(n+1)thandnth spectrum slice respectively, n = 1, 2, …,N. The required optical frequency allocation to the slices is obtained by solving the recursive relations substituting the fiber time delay quadratic equationτ(f), and is given by

fn+1=fn+[(fn+0.5b1/b2)+fn2+0.25b12/b22+b1fn/b2+Δt/b2]
(5)

Figure 3(a)
Fig. 3 (a) Simulated wavelength locations of the 33slices; (b) Measured optical spectra of the spectrum slices.
shows the predicted wavelength locations of the 33 channels for the Corning MetroCor fiber used in the experiment, for a filter time delay step of 170ps. The measured optical spectrum slices obtained using the slicing filter, based on the wavelength allocation and for uniform weighting are shown in Fig. 3(b), and this shows slightly increased channel spacing towards the longer wavelength end in order to provide a constant basic time delay between consecutive taps.

First, a microwave photonic filter with only positive coefficients was configured by propagating the modulated broadband light source propagated into only one port of the dispersion controlled spectrum slicing filter. Each slice channel was programmed to have a 3dB channel bandwidth of 0.41 nm and a group delay slope of150ps/nm, which is opposite to the average dispersion of the fiber delay medium. Figure 4
Fig. 4 Measured characteristics of the microwave photonic filter with only positive coefficients (a) from 0.01GHz to 20GHz (b)(c)(d) snapshots for three passbands. ——Measured ——Calculated
shows the RF filter response measured by a vector network analyser (Agilent N5230A), which displays a filter FSR of 5.87 GHz. In comparison to the case when dispersion compensation is not applied, the RF attenuation degradation at the passband frequencies of 5.87 GHz, 11.74 GHz, and 17.61 GHz is significantly improved by 2.5 dB, 14.7 dB and 25.3 dB respectively. Zoom-in snapshots of the three passband responses are also provided in Fig. 4 together with a comparison to the theory. Excellent agreement can be seen between the theoretical prediction and experimental results in all cases.

Next, a bipolar-coefficient microwave photonic filter, which suppressed the baseband response, was obtained by applying the modulated bipolar broadband light source to both input ports of the dispersion controlled spectrum slicing filter. This realised a bipolar-tap microwave filter which had the same FSR of 5.87 GHz, without changing the rest of the setup. Figure 5
Fig. 5 Measured characteristics of the bipolar-coefficient microwave photonic filter (a) from 0.01GHz to 20GHz (b)(c)(d) snapshots for three passbands. —— Measured ——Calculated.
shows the measured RF filter response. In comparison to the case when dispersion compensation is not applied, the RF attenuation degradation at the passband frequencies of 2.93 GHz, 8.81 GHz, and 14.67 GHz was improved by 0.5 dB, 6.5 dB and 39.3 dB respectively, which significantly improved the filter high frequency performance. The excellent agreement between the measurement and theoretical results verifies the analytical theory, as shown in Fig. 5, which also displays zoom-in snapshots of the passband responses.

We also investigated the effect of the second-order group delay of the dispersive optical fiber on the RF performance of the microwave photonic filter, by deriving the filter coefficient considering both the second order and linear group delay factor of the dispersive element, which is given by
L'n(fm)=signnWnfnfn+g0(ffn)[g0(ffn+fm)ej(2b2f+(b1d))πfm2+g0(ffnfm)ej(2b2f+(b1d))πfm2]×ej2πfm[b2(f2fn2)+(b1d)(ffn)]df
(6)
Here the dispersion value within each channel of the dispersive controlled spectrum slicing filter is set as –d, which is the opposite of the average dispersion of the fiber. It can be seen the residual secondary delay term generates a phase factor to the filter coefficient(L'n(fm)), which causes a complex interaction to the filter response.

Figure 6
Fig. 6 Comparison between the RF passband responses of the 33-tap bipolar filter, when an ideal linear time delay line is used and when the actual experimental fiber delay line, which exhibits second order group delay, are used as the delay medium.
shows a comparison between the RF passband responses of the 33-tap bipolar filter with an FSR of 5.87 GHz and around the third passband over a span of 12.5-17 GHz, when an ideal linear time delay line is used and when the actual experimental fiber delay line exhibiting second order group delay, are used as the delay medium. A difference of 0.23 dB between the two RF responses is observed at the third filter passband. The RF responses at the lower frequency passbands (< 8.81 GHz) are also compared and a maximum RF difference of less than 0.06 dB is observed. These results show that the fiber second order group delay effect is negligible for frequencies below 20 GHz, once the multiple spectrum slices are relocated to maintain a constant delay step. Note that the typical dispersion slope of Corning standard single mode optical fiber is only0.8ps/nm2for accumulating the 150ps/nm dispersion value, which is even less than the Corning MetroCor fiber used in the experiment.

We further investigated the filter performance improvement for different FSR values and for different spectrum slice bandwidths, for either an ideal linear optical delay line or for the MetroCor second order fiber group delay line used in the experiments. Figure 7
Fig. 7 Simulated 33-tap RF response improvement for the first to the fourth passbands for different filter FSR values: (a) using an ideal linear delay line (b) using the experimental delay line that has second order group delay effects. Circles, 5 GHz; squares, 7 GHz; triangles, 9 GHz; crosses, 11GHz.
shows the RF response amplitude improvement of the simulated 33-tap bipolar-coefficient filter response, over the first few passbands for various FSR values of 5 GHz, 7 GHz, 9 GHz and 11 GHz respectively. The results show that the RF response is significantly improved by implementing the dispersion controlled slicing filter, especially at high frequency. Note that the RF filter based on the experimental fiber delay line performs quite similarly to the RF filter that uses the ideal linear optical delay line, for the first three passbands. Further improvement of the RF amplitude passband response can be achieved by reducing the second order group delay factor of the dispersive fiber. By comparing Figs. 7(a) and 7(b) it can be seen that over 11dB further improvement at the fourth passband of the 7 GHz FSR (at 24.5 GHz), can be realized if the second order group delay factor in the dispersive optical fiber is compensated, and this can be achieved by using cascaded optical fibers [17

17. Y. M. Chang, H. Chung, and J. H. Lee, “High Q microwave filter using incoherent, continuous-wave supercontinuum and dispersion-profiled fiber,” IEEE Photon. Technol. Lett. 19(24), 2042–2044 (2007). [CrossRef]

]. Nevertheless, for both cases, the RF response improvements at the fourth filter passband are all beyond 25 dB, which proves that this filter design is effective for different FSR values.

We also investigated the RF response improvement for different bandwidths of the spectrum slices. The results are illustrated in Fig. 8
Fig. 8 Simulated 33-tap RF Response improvement for the first to the fourth passbands for different bandwidth spectrum slices, with an FSR of 11 GHz: (a) using the ideal linear delay line (b) using the experimental delay line that has second order group delay effects. Circles, 30 GHz; squares, 50 GHz; triangles, 70 GHz; crosses, 90 GHz.
. In the simulation, a super-Gaussian shape was used to model the shape of the experimental spectrum sliced source, and an RF filter with an FSR of 11GHz was used as an example in the simulation. Again, the new microwave photonic filter enables the achievement of a significant RF improvement at the filter passbands. For the RF frequencies of less than 27.5 GHz, the RF improvement of the filter based on the two schemes, the ideal linear delay line and the experimental fiber delay are comparable. Moreover, the simulation results show that at the fourth passband RF frequency, which is as high as 38.5 GHz, the RF response improvement using the experimental MetroCor fiber delay line can be further improved by around 10 dB if the second group delay factor is reduced.

The tunability and reconfigurability of the microwave photonic filter was demonstrated via software control of the spectrum slice center frequencies and the corresponding tap weight. Here, a 33-tap microwave photonic filter was implemented to demonstrate the passband tunability. This was achieved by decreasing the spectrum slice spacing by programming the slice center frequencies through the dispersion controlled spectrum slicing filter; while keeping each channel dispersion value the same. Figure 9(a)
Fig. 9 Measured 33-tap filter RF response (a) tuned to a passband of 11 GHz (b) switched baseband-suppressed filter with 33 bipolar taps. —— Measured —— Calculated.
shows the filter response of a 33-tap tuned from 5.87 GHz to 11.03 GHz. By routing every other spectrum slice to the alternative port of the slicing filter, a switched baseband-suppressed filter with 33 bipolar taps was obtained and is presented in Fig. 9(b). Excellent agreement can be seen from the comparison between the measured and calculated RF response.

Finally, a 33-tap bipolar coefficient microwave photonic filter that had a flat-top response, and which had a switchable capability was demonstrated. A Gaussian-sinc windowing function which synthesizes both positive and negative coefficients was applied by adjusting the amplitude of the dispersion controlled optical slicing filter to spectrally filter the modulated broadband light source directed from port 1 and port 2 of the dual-output EOM respectively. Figure 10
Fig. 10 Measured 33-tap square-top RF filter response (a) bipolar Gaussian-sinc profile (b) switched bipolar Gaussian-sinc profile.
shows RF measurements along with the filter tap profiles illustrated in the insets. A square-shape RF response centered at 11.03 GHz and having a 3 dB bandwidth of 0.99 GHz is displayed in Fig. 10(a). It has a shape factor of 1.6, which is defined as the ratio of −20 dB to −3 dB bandwidth. The filter has over 30 dB stopband rejection and has a flat-top passband. The amplitude of the filter passband ripple is less than 0.12 dB. By switching every other optical slice to the alternative port of the dispersion controlled slicing filter in order to alternate the polarity of these filter coefficients, the RF filter can be switched off, as shown in Fig. 10(b).

5. Conclusion

A new switchable microwave photonic filter based on a novel spectrum slicing technique has been presented. The processor enables programmable multi-tap generation with general transfer function characteristics and offers tunability, reconfigurabiliy, and switchability. It is based on connecting a dispersion controlled spectrum slicing filter after the modulated bipolar broadband light source, which consequently creates multiple spectrum slices with bipolarity, and compensates dispersion induced RF degradation simultaneously within a single device. A detailed theoretical model for this microwave photonic filter design has been presented. Experimental results have been presented which verify the model, and demonstrate a 33 bipolar-tap microwave filter with significant reduction of passband attenuations at high frequencies. The RF response improvement of the new microwave photonic filter has been investigated, for both an ideal linear group delay line and for the experimental fiber delay line that has second order group delay and the results have shown that this new structure is effective for RF filters with various FSR values and spectrum slice bandwidths. Finally, we have demonstrated a switchable bipolar filter that has a square-top bandpass filter response with more than 30 dB stopband attenuation that can be switched on/off via software control.

Acknowledgments

The research was supported by the Australian Research Council. The authors also would like to acknowledge Shanghai Jiaotong Open Project program of the State Key Laboratory of Advanced Optical Communication Systems and Networks, and valuable discussions with Dr. M. Roelens, Dr. S. Frisken and Dr. S. Poole from Finisar Australia.

References and Links

1.

R. A. Minasian, “Photonic signal processing of microwave signals,” IEEE Trans. Microw. Theory Tech. 54(2), 832–846 (2006). [CrossRef]

2.

J. P. Yao, “Microwave photonics,” J. Lightwave Technol. 27(3), 314–335 (2009). [CrossRef]

3.

J. Capmany, D. Pastor, and B. Ortega, “New and flexible fiber-optic delay-line filters using chirped Bragg gratings and laser arrays,” IEEE Trans. Microw. Theory Tech. 47(7), 1321–1326 (1999). [CrossRef]

4.

J. L. Chen and R. A. Minasian, “Novel synthesised photonic signal processor with hardware compression,” IEEE Photon. Technol. Lett. 17(4), 896–898 (2005). [CrossRef]

5.

F. Zeng and J. Yao, “Investigation of phase-modulator-based all-optical bandpass microwave filter,” J. Lightwave Technol. 23(4), 1721–1728 (2005). [CrossRef]

6.

T. X. H. Huang, X. Yi, and R. A. Minasian, “New multiple-tap, general-response, reconfigurable photonic signal processor,” Opt. Express 17(7), 5358–5363 (2009). [CrossRef] [PubMed]

7.

J. Capmany, D. Pastor, and B. Ortega, “Fiber optic microwave and millimeter-wave filter with high density sampling and very high sidelobe suppression using sub nanometer optical spectrum slicing,” Electron. Lett. 35(6), 494–496 (1999). [CrossRef]

8.

D. Pastor, B. Ortega, J. Capmany, S. Sales, A. Martinez, and P. Muñoz, “Optical microwave filter based on spectral slicing by use of arrayed waveguide gratings,” Opt. Lett. 28(19), 1802–1804 (2003). [CrossRef] [PubMed]

9.

B. A. L. Gwandu, W. Zhang, J. A. R. Williams, L. Zhang, and I. Bennion, “Microwave photonic filtering using Gaussian-profiled superstructured fiber Bragg grating and dispersive fiber,” Electron. Lett. 38(22), 1328–1330 (2002). [CrossRef]

10.

X. Yi and R. A. Minasian, “Dispersion induced RF distortion of spectrum-sliced microwave-photonic filters,” IEEE Trans. Microw. Theory Tech. 54(2), 880–886 (2006). [CrossRef]

11.

X. Yi, L. Li, T. X. H. Huang, and R. A. Minasian, “Elimination of dispersion-induced RF distortion in spectrum sliced microwave photonic filters,” IEEE International Topical Meeting on Microwave Photonics (MWP), Montreal, Canada, 389–392 Oct. 2010.

12.

L. Li, X. Yi, and R. A. Minasian, “New microwave photonic spectrum sliced filter with continuous tunability,” Opto-Electronics and Communications Conference (OECC), Taiwan, 192–193 Jul. 2011.

13.

L. Li, X. Yi, T. X. H. Huang, and R. A. Minasian, “Microwave photonic filter based on dispersion controlled spectrum slicing technique,” Electron. Lett. 47(8), 511–512 (2011). [CrossRef]

14.

G. Baxter, S. Frisken, D. Abakoumov, H. Zhou, I. Clarke, A. Bartos, and S. Poole, “Highly programmable wavelength selective switch based on liquid crystal on silicon switching elements,” in Optical Fiber Communication Conference and Exposition and The National Fiber Optic Engineers Conference, Technical Digest (CD) (Optical Society of America, 2006), paper OTuF2.

15.

C. H. Cox III, Analog Optical Links: Theory and Practice (Cambridge University Press, 2004).

16.

M. A. F. Roelens, S. Frisken, J. A. Bolger, D. Abakoumov, G. Baxter, S. Poole, and B. J. Eggleton, “Dispersion trimming in a reconfigurable wavelength selective switch,” J. Lightwave Technol. 26(1), 73–78 (2008). [CrossRef]

17.

Y. M. Chang, H. Chung, and J. H. Lee, “High Q microwave filter using incoherent, continuous-wave supercontinuum and dispersion-profiled fiber,” IEEE Photon. Technol. Lett. 19(24), 2042–2044 (2007). [CrossRef]

OCIS Codes
(070.1170) Fourier optics and signal processing : Analog optical signal processing
(070.2615) Fourier optics and signal processing : Frequency filtering
(060.5625) Fiber optics and optical communications : Radio frequency photonics

ToC Category:
Fourier Optics and Signal Processing

History
Original Manuscript: March 21, 2012
Revised Manuscript: April 13, 2012
Manuscript Accepted: April 13, 2012
Published: May 6, 2012

Citation
Liwei Li, Xiaoke Yi, Thomas X. H. Huang, and Robert A. Minasian, "Distortion-free spectrum sliced microwave photonic signal processor: analysis, design and implementation," Opt. Express 20, 11517-11528 (2012)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-20-10-11517


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References

  1. R. A. Minasian, “Photonic signal processing of microwave signals,” IEEE Trans. Microw. Theory Tech.54(2), 832–846 (2006). [CrossRef]
  2. J. P. Yao, “Microwave photonics,” J. Lightwave Technol.27(3), 314–335 (2009). [CrossRef]
  3. J. Capmany, D. Pastor, and B. Ortega, “New and flexible fiber-optic delay-line filters using chirped Bragg gratings and laser arrays,” IEEE Trans. Microw. Theory Tech.47(7), 1321–1326 (1999). [CrossRef]
  4. J. L. Chen and R. A. Minasian, “Novel synthesised photonic signal processor with hardware compression,” IEEE Photon. Technol. Lett.17(4), 896–898 (2005). [CrossRef]
  5. F. Zeng and J. Yao, “Investigation of phase-modulator-based all-optical bandpass microwave filter,” J. Lightwave Technol.23(4), 1721–1728 (2005). [CrossRef]
  6. T. X. H. Huang, X. Yi, and R. A. Minasian, “New multiple-tap, general-response, reconfigurable photonic signal processor,” Opt. Express17(7), 5358–5363 (2009). [CrossRef] [PubMed]
  7. J. Capmany, D. Pastor, and B. Ortega, “Fiber optic microwave and millimeter-wave filter with high density sampling and very high sidelobe suppression using sub nanometer optical spectrum slicing,” Electron. Lett.35(6), 494–496 (1999). [CrossRef]
  8. D. Pastor, B. Ortega, J. Capmany, S. Sales, A. Martinez, and P. Muñoz, “Optical microwave filter based on spectral slicing by use of arrayed waveguide gratings,” Opt. Lett.28(19), 1802–1804 (2003). [CrossRef] [PubMed]
  9. B. A. L. Gwandu, W. Zhang, J. A. R. Williams, L. Zhang, and I. Bennion, “Microwave photonic filtering using Gaussian-profiled superstructured fiber Bragg grating and dispersive fiber,” Electron. Lett.38(22), 1328–1330 (2002). [CrossRef]
  10. X. Yi and R. A. Minasian, “Dispersion induced RF distortion of spectrum-sliced microwave-photonic filters,” IEEE Trans. Microw. Theory Tech.54(2), 880–886 (2006). [CrossRef]
  11. X. Yi, L. Li, T. X. H. Huang, and R. A. Minasian, “Elimination of dispersion-induced RF distortion in spectrum sliced microwave photonic filters,” IEEE International Topical Meeting on Microwave Photonics (MWP), Montreal, Canada, 389–392 Oct. 2010.
  12. L. Li, X. Yi, and R. A. Minasian, “New microwave photonic spectrum sliced filter with continuous tunability,” Opto-Electronics and Communications Conference (OECC), Taiwan, 192–193 Jul. 2011.
  13. L. Li, X. Yi, T. X. H. Huang, and R. A. Minasian, “Microwave photonic filter based on dispersion controlled spectrum slicing technique,” Electron. Lett.47(8), 511–512 (2011). [CrossRef]
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