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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 20, Iss. 24 — Nov. 19, 2012
  • pp: 26292–26298
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Linear phase-and-frequency-modulated photonic links using optical discriminators

J. M. Wyrwas, R. Peach, S. Meredith, C. Middleton, M. S. Rasras, Kun-Yii Tu, M. P. Earnshaw, F. Pardo, M. A. Cappuzzo, E. Y. Chen, L. T. Gomez, F. Klemens, R. Keller, C. Bolle, L. Zhang, L. Buhl, M. C. Wu, Y.K. Chen, and R. DeSalvo  »View Author Affiliations


Optics Express, Vol. 20, Issue 24, pp. 26292-26298 (2012)
http://dx.doi.org/10.1364/OE.20.026292


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Abstract

We report our experimental results for linear analog optical links that use phase or frequency modulation and optical discrimination. The discriminators are based on two architectures: a cascaded MZI FIR lattice filter and a ring assisted MZI (RAMZI) IIR filter. For both types of discriminators, we demonstrate > 6 dB improvement in the link’s third-order output intercept point (OIP3) over a MZM link. We show that the links have low second-order distortion when using balanced detection. Using high optical power, we demonstrate an OIP3 of 39.2 dBm. We also demonstrate 4.3dB improvement in signal compression.

© 2012 OSA

1. Introduction

Although the modulation may be linear, distortion is introduced in the demodulation process. We have designed demodulators which use optical filters to convert the phase and frequency modulation into AM before detection at a photodetector. The filters are called phase and frequency discriminators. The demodulation process is called phase-modulation or frequency-modulation direct-detection (PM-DD or FM-DD), filter-slope detection, or interferometric detection. Authors have proposed various discriminator-filters to optimize the demodulation for low distortion, including birefringent crystals [3

3. S. E. Harris, E. O. Ammann, and I. C. Chang, “Optical network synthesis using birefringent crystals,” J. Opt. Soc. Am. 54(10), 1267–1278 (1964). [CrossRef]

], asymmetrical Mach Zehnder interferometers (a-MZI) [4

4. I. P. Kaminow, “Balanced optical discriminator,” Appl. Opt. 3(4), 507–510 (1964). [CrossRef]

,5

5. V. J. Urick, F. Bucholtz, P. S. Devgan, J. D. McKinney, and K. J. Williams, “Phase modulation with interferometric detection as an alternative to intensity modulation with direct detection for analog-photonic links,” IEEE Trans. Microw. Theory Tech. 55(9), 1978–1985 (2007). [CrossRef]

], Fabry-Perot filters [6

6. W. Way, Y. Lo, T. Lee, and C. Lin, “Direct detection of closely spaced optical FM-FDM Gb/s microwave PSK signals,” IEEE Photon. Technol. Lett. 3(2), 176–178 (1991). [CrossRef]

], fiber Bragg gratings [7

7. P. Driessen, T. Darcie, and J. Zhang, “Analysis of a class-B microwave-photonic link using optical frequency modulation,” J. Lightwave Technol. 26(15), 2740–2747 (2008). [CrossRef]

] and tunable integrated filters [8

8. X. Xie, J. Khurgin, J. Kang, and F.-S. Choa, “Ring-assisted frequency discriminator with improved linearity,” IEEE Photon. Technol. Lett. 14(8), 1136–1138 (2002). [CrossRef]

,9

9. D. Marpaung, C. Roeloffzen, A. Leinse, and M. Hoekman, “A photonic chip based frequency discriminator for a high performance microwave photonic link,” Opt. Express 18(26), 27359–27370 (2010). [CrossRef] [PubMed]

].

2. Link architecture

We implement the complementary linear-field filters using two different types of tunable PLC filters: a MZI FIR lattice filter and a ring assisted MZI (RAMZI) IIR filter. A single stage of each filter is illustrated in Fig. 2
Fig. 2 (a) Filter stage for an FIR lattice filter (b) Filter stage for an IIR, RAMZI filter.
. These filters can be thermally tuned to implement arbitrary filter transfer functions. Our FIR filter is a sixth-order filter with 120 GHz free-spectral range. An Nth order FIR lattice filter is composed of N a-MZIs (delay line interferometers), and N + 1 symmetrical MZIs (switches) to control the coupling into each branch. Up to tenth-order FIR lattice filters have been previously fabricated for dispersion compensation and gain equalization [12

12. K. Takiguchi, K. Jinguji, K. Okamoto, and Y. Ohmori, “Variable group-delay dispersion equalizer using lattice-form programmable optical filter on planar lightwave circuit,” IEEE J. Sel. Top. Quantum Electron. 2(2), 270–276 (1996). [CrossRef]

]. The RAMZI filter is an all pass ring resonator structure coupled to the delay arm of an MZI. We report on the physical design and fabrication, and tuning of this filter in [13

13. M. S. Rasras, Y. K. Chen, K. Yii, M. P. Earnshaw, F. Pardo, M. A. Cappuzzo, E. Y. Chen, L. T. Gomez, F. Klemens, R. Keller, C. Bolle, L. Buhl, J. M. Wyrwas, M. C. Wu, R. Peach, C. Middleton, and R. DeSalvo, “A reconfigurable linear optical FM discriminator,” IEEE Photon. Technol. Lett. 24(20), 1856–1859 (2012).

], while the system measurement results are contained within this work.

3. Characterization

4. Link results

4.1 Phase-modulated link with FIR filter

We report distortion measurements made with a single branch of the filter and single-ended detection. This is sufficient to determine whether the system can improve upon the third-order distortion over the MZM. With tones 2 GHz and 2 GHz + 100 kHz fundamental frequencies, we stepped the wavelength of the laser to determine the optimal bias point on the filter. At each wavelength, we collected the receiver power at 2 GHz and the third-order intermodulation distortion (IMD3) power at 2 GHz – 100 kHz. The result is shown in Fig. 5(a)
Fig. 5 (a) Fundamental and third-order intermodulation distortion versus laser wavelength. The modulation power is fixed at 10 dBm and the photocurrent is fixed at 0.11 mA. (b) Fundamental and third-order intermodulation distortion versus modulation power. The photocurrent is fixed at 0.11 mA and the wavelength is fixed at 1549.93 nm.
. At the optimal bias wavelength, we stepped the modulation power to demonstrate the distortion was cubic in power. The data is plotted in Fig. 5(b). The OIP3 was improved 6.7 dB better than a Mach Zehnder with the same received photocurrent.

4.2 Phase-modulated link with IIR filter

We also performed PM-DD measurements with the IIR filter. Figure 6
Fig. 6 (a) Layout of IIR filter chip. (b) Achieved filter amplitude and phase.
shows the layout and tuned transfer function of one of the branches of the RAMZI filter. The plotted transfer function is normalized to 5 dB insertion loss. The transfer function was measured with an OVNA. The second branch was tuned to a transfer function with opposite slope.

4.3 Frequency-modulated link with IIR filter

5. Conclusions

Acknowledgments

This material is based upon work funded by DARPA’s TROPHY program, under AFRL Contract No. FA8650-10-C-7003. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of DARPA or the United States Air Force.

References and links

1.

Y. Li, R. Wang, A. Bhardwaj, S. Ristic, and J. Bowers, “High linearity InP-based phase modulators using a shallow quantum-well design,” IEEE Photon. Technol. Lett. 22(18), 1340–1342 (2010). [CrossRef]

2.

X. Xie, J. Khurgin, F. S. Choa, X. Yu, J. Cai, J. Yan, X. Ji, Y. Gu, Y. Fang, Y. Sun, G. Ru, and Z. Chen, “A model for optimization of the performance of frequency-modulated DFB semiconductor laser,” IEEE J. Quantum Electron. 41(4), 473–482 (2005). [CrossRef]

3.

S. E. Harris, E. O. Ammann, and I. C. Chang, “Optical network synthesis using birefringent crystals,” J. Opt. Soc. Am. 54(10), 1267–1278 (1964). [CrossRef]

4.

I. P. Kaminow, “Balanced optical discriminator,” Appl. Opt. 3(4), 507–510 (1964). [CrossRef]

5.

V. J. Urick, F. Bucholtz, P. S. Devgan, J. D. McKinney, and K. J. Williams, “Phase modulation with interferometric detection as an alternative to intensity modulation with direct detection for analog-photonic links,” IEEE Trans. Microw. Theory Tech. 55(9), 1978–1985 (2007). [CrossRef]

6.

W. Way, Y. Lo, T. Lee, and C. Lin, “Direct detection of closely spaced optical FM-FDM Gb/s microwave PSK signals,” IEEE Photon. Technol. Lett. 3(2), 176–178 (1991). [CrossRef]

7.

P. Driessen, T. Darcie, and J. Zhang, “Analysis of a class-B microwave-photonic link using optical frequency modulation,” J. Lightwave Technol. 26(15), 2740–2747 (2008). [CrossRef]

8.

X. Xie, J. Khurgin, J. Kang, and F.-S. Choa, “Ring-assisted frequency discriminator with improved linearity,” IEEE Photon. Technol. Lett. 14(8), 1136–1138 (2002). [CrossRef]

9.

D. Marpaung, C. Roeloffzen, A. Leinse, and M. Hoekman, “A photonic chip based frequency discriminator for a high performance microwave photonic link,” Opt. Express 18(26), 27359–27370 (2010). [CrossRef] [PubMed]

10.

C. H. Cox, “Distortion models and measures,” in Analog Optical Links: Theory and Practice (Cambridge University Press, 2004), pp. 202–216.

11.

J. M. Wyrwas and M. C. Wu, “Dynamic range of frequency modulated direct-detection analog fiber optic links,” J. Lightwave Technol. 27(24), 5552–5562 (2009). [CrossRef]

12.

K. Takiguchi, K. Jinguji, K. Okamoto, and Y. Ohmori, “Variable group-delay dispersion equalizer using lattice-form programmable optical filter on planar lightwave circuit,” IEEE J. Sel. Top. Quantum Electron. 2(2), 270–276 (1996). [CrossRef]

13.

M. S. Rasras, Y. K. Chen, K. Yii, M. P. Earnshaw, F. Pardo, M. A. Cappuzzo, E. Y. Chen, L. T. Gomez, F. Klemens, R. Keller, C. Bolle, L. Buhl, J. M. Wyrwas, M. C. Wu, R. Peach, C. Middleton, and R. DeSalvo, “A reconfigurable linear optical FM discriminator,” IEEE Photon. Technol. Lett. 24(20), 1856–1859 (2012).

14.

J. M. Wyrwas and M. C. Wu, “High dynamic-range microwave photonic links using maximally linear FIR optical filters,” in Optical Fiber Communication Conference, OSA Technical Digest (CD) (Optical Society of America, 2010), paper JWA43.

15.

V. E. Houtsma, T. Hu, N. Weimann, R. Kopf, A. Tate, J. Frackoviak, R. Reyes, Y. Chen, and L. Zhang, “A 1 W linear high-power InP balanced uni-traveling carrier photodetector,” in 37th European Conference and Exposition on Optical Communications, OSA Technical Digest (CD) (Optical Society of America, 2011), paper Tu.3.LeSaleve.6.

OCIS Codes
(060.2360) Fiber optics and optical communications : Fiber optics links and subsystems
(060.5060) Fiber optics and optical communications : Phase modulation
(070.6020) Fourier optics and signal processing : Continuous optical signal processing
(130.3120) Integrated optics : Integrated optics devices
(350.4010) Other areas of optics : Microwaves
(060.5625) Fiber optics and optical communications : Radio frequency photonics

ToC Category:
Fiber Optics and Optical Communications

History
Original Manuscript: August 30, 2012
Revised Manuscript: October 4, 2012
Manuscript Accepted: October 9, 2012
Published: November 6, 2012

Citation
J. M. Wyrwas, R. Peach, S. Meredith, C. Middleton, M. S. Rasras, Kun-Yii Tu, M. P. Earnshaw, F. Pardo, M. A. Cappuzzo, E. Y. Chen, L. T. Gomez, F. Klemens, R. Keller, C. Bolle, L. Zhang, L. Buhl, M. C. Wu, Y.K. Chen, and R. DeSalvo, "Linear phase-and-frequency-modulated photonic links using optical discriminators," Opt. Express 20, 26292-26298 (2012)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-20-24-26292


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References

  1. Y. Li, R. Wang, A. Bhardwaj, S. Ristic, and J. Bowers, “High linearity InP-based phase modulators using a shallow quantum-well design,” IEEE Photon. Technol. Lett.22(18), 1340–1342 (2010). [CrossRef]
  2. X. Xie, J. Khurgin, F. S. Choa, X. Yu, J. Cai, J. Yan, X. Ji, Y. Gu, Y. Fang, Y. Sun, G. Ru, and Z. Chen, “A model for optimization of the performance of frequency-modulated DFB semiconductor laser,” IEEE J. Quantum Electron.41(4), 473–482 (2005). [CrossRef]
  3. S. E. Harris, E. O. Ammann, and I. C. Chang, “Optical network synthesis using birefringent crystals,” J. Opt. Soc. Am.54(10), 1267–1278 (1964). [CrossRef]
  4. I. P. Kaminow, “Balanced optical discriminator,” Appl. Opt.3(4), 507–510 (1964). [CrossRef]
  5. V. J. Urick, F. Bucholtz, P. S. Devgan, J. D. McKinney, and K. J. Williams, “Phase modulation with interferometric detection as an alternative to intensity modulation with direct detection for analog-photonic links,” IEEE Trans. Microw. Theory Tech.55(9), 1978–1985 (2007). [CrossRef]
  6. W. Way, Y. Lo, T. Lee, and C. Lin, “Direct detection of closely spaced optical FM-FDM Gb/s microwave PSK signals,” IEEE Photon. Technol. Lett.3(2), 176–178 (1991). [CrossRef]
  7. P. Driessen, T. Darcie, and J. Zhang, “Analysis of a class-B microwave-photonic link using optical frequency modulation,” J. Lightwave Technol.26(15), 2740–2747 (2008). [CrossRef]
  8. X. Xie, J. Khurgin, J. Kang, and F.-S. Choa, “Ring-assisted frequency discriminator with improved linearity,” IEEE Photon. Technol. Lett.14(8), 1136–1138 (2002). [CrossRef]
  9. D. Marpaung, C. Roeloffzen, A. Leinse, and M. Hoekman, “A photonic chip based frequency discriminator for a high performance microwave photonic link,” Opt. Express18(26), 27359–27370 (2010). [CrossRef] [PubMed]
  10. C. H. Cox, “Distortion models and measures,” in Analog Optical Links: Theory and Practice (Cambridge University Press, 2004), pp. 202–216.
  11. J. M. Wyrwas and M. C. Wu, “Dynamic range of frequency modulated direct-detection analog fiber optic links,” J. Lightwave Technol.27(24), 5552–5562 (2009). [CrossRef]
  12. K. Takiguchi, K. Jinguji, K. Okamoto, and Y. Ohmori, “Variable group-delay dispersion equalizer using lattice-form programmable optical filter on planar lightwave circuit,” IEEE J. Sel. Top. Quantum Electron.2(2), 270–276 (1996). [CrossRef]
  13. M. S. Rasras, Y. K. Chen, K. Yii, M. P. Earnshaw, F. Pardo, M. A. Cappuzzo, E. Y. Chen, L. T. Gomez, F. Klemens, R. Keller, C. Bolle, L. Buhl, J. M. Wyrwas, M. C. Wu, R. Peach, C. Middleton, and R. DeSalvo, “A reconfigurable linear optical FM discriminator,” IEEE Photon. Technol. Lett.24(20), 1856–1859 (2012).
  14. J. M. Wyrwas and M. C. Wu, “High dynamic-range microwave photonic links using maximally linear FIR optical filters,” in Optical Fiber Communication Conference, OSA Technical Digest (CD) (Optical Society of America, 2010), paper JWA43.
  15. V. E. Houtsma, T. Hu, N. Weimann, R. Kopf, A. Tate, J. Frackoviak, R. Reyes, Y. Chen, and L. Zhang, “A 1 W linear high-power InP balanced uni-traveling carrier photodetector,” in 37th European Conference and Exposition on Optical Communications, OSA Technical Digest (CD) (Optical Society of America, 2011), paper Tu.3.LeSaleve.6.

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