Figure 4 Photograph of DBR multi-mode laser to generate inter-modal oscillation.

InP Synthesizer

Figure 4

Figure 4 Photograph of DBR multi-mode laser to generate inter-modal oscillation.

The second innovation is a monolithically integrated design, where the whole synthesizer is realized as a single InP IC, which will operate beyond K-Band. RF oscillation is achieved using the intermodal oscillation output of a long multi-section, multi-quantum well DBR semiconductor laser (see Figure 4), which provides the laser realization for the synthesizer.31-33 The laser consists of four major sections,34 the distributed Bragg reflector (DBR), gain medium, phase tuning section and electro-absorption modulator. The DBR is used as a filter to select the laser output frequency,35 and the phase section tunes the intermodal output to achieve the desired RF output. With this technique, the whole system can be realized within a 5 mm x 2 mm chip without an outside circuit, which is significantly smaller than any conventional RF synthesizer. The performance of the intermodal output at 11.6 GHz is shown in Figure 5. Free running, the output phase noise is around −30 dBc/Hz at 10 kHz offset. With SILTSPLL23 applied, the phase noise drops to −98 dBc/Hz at 10 kHz offset with an offset phase modulator bias of 0 V, yielding a 68 dB phase noise reduction from the free-running case.

Figure 5

Figure 5 SILTPLL-based inter-modal RF phase noise vs. PM bias using SIL of 3 km, STPLL of 500 m, 1 km and 5 km. PM bias of 0 V, –3 V and –5 V are for RF frequency tuning of ~800 MHz from 11.549, 11.938 and 12.272 GHz, respectively.

CONCLUSION

The first article in this two-part series demonstrated a computer-controlled K-Band synthesizer using a MZM-based OEO architecture. Suppression of intermodal oscillation from the long fiber-optic delay lines reduced the close-in phase noise,23 with measured results about −130 dBc/Hz at 10 kHz offset over the full frequency range from 16 to 24 GHz. This second article discusses approaches for reducing the size and cost of the OEO synthesizer by using a PhC-PM device and a Sagnac loop phase modulator to intensity modulator convertor.28-29 Using the PhC-PM instead of the MZM OEO requires forced SILPLL techniques and achieves an estimated −148 dBc/Hz phase noise at 10 kHz offset. PhC-PM design concepts compatible with Si photonics could be integrated with SiGe BiCMOS technology for a full monolithic integration of the photonic and electronic circuits. Forced-oscillation control of an InP based DBR semiconductor laser is another alternative to full monolithic integration. Various high quality factor, low loss optical resonators (e.g., Si3N4 and SiO2) could be employed in place of km-long fiber-optic delay lines to further reduce the size of the optical components used in the SILPLL structure. For example, whispering gallery mode resonators with Q-factors to 108 and optical ring resonators with Q-factors to 105 have been demonstrated,36 which could be integrated using a Si photonics process. These proposed solutions make the realization of OEOs very attractive for future generations of instrumentation, communications and sensing.

References

  1. R. Adler, “A Study of Locking Phenomena In Oscillators,” Proceedings of the IRE 34, No. 6, 1946, pp. 351–357.
  2. U. L. Rohde, “Digital PLL Frequency Synthesizers: Theory and Design,” Prentice Hall, New York, 1983.
  3. A. S. Daryoush, “Optical Synchronization of Millimeter-Wave Oscillators for Distributed Millimeter-wave Systems,” IEEE Trans. on Microwave Theory and Techniques, Vol. 38, No. 5, May 1990, pp. 1371–1373.
  4. P. R. Herczfeld, A. S. Daryoush, A. Rosen, A. K. Sharma and V. M. Contarino, “Indirect Subharmonic Optical Injection Locking of a Millimeter Wave IMPATT Oscillator,” IEEE Trans. on Microwave Theory and Techniques, Vol. 34, No. 12, December 1986, pp. 1371–1376.
  5. A. S. Daryoush, P. R. Herczfeld, P. Wahi and Z. Turski, “Comparison of Indirect Optical Injection Locking Techniques of Multiple X-Band Oscillators,” IEEE Trans. on Microwave Theory and Techniques, Vol. 34, No. 12, December 1986, pp. 1363–1370.
  6. S. Lipsky and A. S. Daryoush, “Fiber Optic Methods for Injection-Locked Oscillators,” Microwave Journal, Vol. 35, No. 1, January 1992, pp. 80−88.
  7. E. C. Niehenke and P. Herczfeld, “An Optical Link for W-Band Transmit/Receive Applications,”1997 IEEE International Microwave Symposium Digest, Vol. 1, pp. 35–38.
  8. A. S. Daryoush, “Phase Noise Degradation in Nonlinear Fiber Optic Links Distribution Networks for Communication Satellites,” Microwave Photonics from Components to Applications and Systems, Kluwer Academic Publishers, May 2003.
  9. X. S. Yao and L. Maleki, “Optoelectronic Microwave Oscillator,” J. Opt. Soc. Am., B 13, 1996, pp. 1725–1735.
  10. A. S. Daryoush, A. K. Poddar, T. Sun and U. L. Rohde, “Optoelectronic Oscillators: Recent and Emerging Trends,” Microwave Journal, October 2018, pp. 58–76.
  11. S. Fedderwitz, A. Stohr, S. Babiel, V. Rymanov and D. Jager, “Opto-Electronic Dual-Loop 50 GHz Oscillator With Wide Tunability and Low Phase Noise,” Proc. of 2010 IEEE Microwave Photonics, pp. 224–226.
  12. M. Kaba et al., “Improving Thermal Stability of Opto-Electronic Oscillators,” IEEE Microwave Magazine, Vol. 7, No. 4, August 2006, pp. 38–47.
  13. A. S. Daryoush, H. W. Li, M. Kaba, G. Bouwmans, D. Decoster, J. Chazelas and F. Deborgies, “Passively Temperature Stable Opto-Electronic Oscillators Employing Photonic Crystal Fibers?,” Proc. of the European Microwave Association, Vol. 3, No. 3, September 2007, pp. 201–209.
  14. L. Zhang, V. Madhavan, R. Patel, A. K. Poddar, U. L. Rohde and A. S. Daryoush, “Ultra Low FM Noise In Passively Temperature Compensated Microwave Opto-Electronic Oscillators,” Proc. IEEE International Microwave and RF Conference, December 2013.
  15. T. Sun, Li. Zhang, A. K. Poddar, U. L. Rohde and A. S. Daryoush, “Frequency Synthesis of Forced Opto-Electronic Oscillators at the X-Band,” Chin. Opt. Lett., Vol. 15, No. 1, January 10, 2017, p. 010009.
  16. A. S. Daryoush, “Phase Noise Degradation in Nonlinear Fiber Optic Links Distribution Networks for Communication Satellites,” Microwave Photonics from Components to Applications and Systems, Kluwer Academic Publishers, May 2003.
  17. A. K. Poddar, U. L. Rohde and A. S. Daryoush, “Self-Injection Locked Phase Locked Loop Optoelectronic Oscillator,” U.S. Patent 20140186045, July 3, 2014.
  18. T. Sun, A. S. Daryoush, A. Poddar, L. Zhang and U. Rohde, “High-Resolution Frequency Synthesizers Over X-Band Using SILPLL Opto-Electronic Oscillators,” 2017 IEEE International Frequency Control Symposium, 2017.
  19. T. Sun, A. S. Daryoush, A. Poddar, L. Zhang and U. Rohde, “High-Resolution X-Band Frequency Synthesizer Using SILPLL Opto-Electronic Oscillators,” IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control.
  20. L. Zhang et al., “Analytical and Experimental Evaluation of SSB Phase Noise Reduction in Self-Injection Locked Oscillators Using Optical Delay Loops,” IEEE Photonics J., Vol. 5, No. 6, December 2013.
  21. L. Zhang et al., “Comparison of Optical Self-Phase Locked Loop Techniques for Frequency Stabilization of Oscillators,” IEEE Photonics J., Vol. 6, No. 5, October 2014, pp. 1–15.
  22. L. Zhang et al., “Self-ILPLL Using Optical Feedback for Phase Noise Reduction in Microwave Oscillators,” IEEE Photonics Technology Letters, Vol. 27, No. 6, 2015, pp. 624–627.
  23. T. Sun et al., “Limits in Timing Jitters of Forced Microwave Oscillator Using Optical Self-ILPLL,” IEEE Photonics Technology Letters, Vol. 29, No. 2, January 15, 2017, pp. 181–184.
  24. A. S. Daryoush, T. Sun, N. Bromhead, A. K. Poddar and U. L. Rohde, “Computer Control of Self Injection Locked Phase Locked Opto-Electronic Oscillator Based K-Band Frequency Synthesizers: Part 1,” Microwave Journal, Vol. 62, No. 8, August 2019, pp. 90–104.
  25. M. Hadjloum, M. El Gibari, H. W. Li and A. S. Daryoush, “Design Challenges of EO Polymer Based Leaky Waveguide Deflector for 40 Gs/s All Optical Analog-To-Digital Converters,” Opt. Commun., Vol. 373, 2016, pp. 82–90.
  26. K. Receveur, K. Wei, M. Hadjloum, M. El Gibari, A. De Rossi, H. Li and A. Daryoush, “Sensitivity Improvement of Broadband Electro-Optic Polymer-Based Optical Phase Modulator Using 1D and 2D Photonic Crystal Structures,” Chin. Opt. Lett. 15, Vol. 15, No. 1, January 10, 2017, p. 010003.
  27. K. Wei and A. S. Daryoush, “Broadband and Sensitive Lateral Optical Phase Modulators Using 1D-PhC for Integrated Si-Photonics,” 2018 International Meeting on Microwave Photonics.
  28. S. E. Hosseini et al., “Low-Drift Optoelectronic Oscillator Based on A Phase Modulator in A Sagnac Loop,” IEEE Transactions on Microwave Theory & Techn., Vol. 65, No. 7, July 2017, pp. 2617–2624.
  29. F. Pantano et al., “Forced Opto-Electronic Oscillators Using Efficient PBG Based Phase Modulators,” 2018 IEEE International Frequency Control Symposium, pp. 1–3.
  30. F. T. Pantano, K. Wei, T. Sun and A. S. Daryoush, “SILPLL Based Forced Opto-Electronic Oscillator Using A Phase Modulator in A Sagnac Loop,” 2018 IEEE Topical Conference on Wireless Sensors and Sensor Networks, pp. 66–69.
  31. T. Sun and A. S. Daryoush, “Ultra-Stable RF Signal Generator Using Beat-Notes Output of DBR Based Multi-Modes Lasers,” 2017 International Topical Meeting on Microwave Photonics, pp. 1–3.
  32. A. S. Daryoush and T. Sun, “Compact Highly Stable Synthesized RF Sources Using Self Mode-Locked Beat-Notes of Multimodes of Multimode Lasers,” U.S. Patent Application No. 62/576,398, October 24, 2017.
  33. A. K. Poddar, U. L. Rohde and A. S. Daryoush, “Optoelectronic Oscillator using Monolithically Integrated Multi-Quantum Well Laser and Phase Modulator,” U.S. Patent Application No. 63/702,970 July 25, 2018.
  34. L. A. Johansson, Y. A. Akulova, G. A. Fish and L. A. Coldren, “Sampled-Grating DBR Laser Integrated with SOA and Tandem Electroabsorption Modulator for Chirp-Control,” Electronics Lett., Vol. 40, No. 1, January 8, 2004, pp. 70–71.
  35. S. Joshi, C. Calò, N. Chimot, M. Radziunas, R. Arkhipov, S. Barbet, A. Accard, A. Ramdane and F. Lelarge, “Quantum Dash Based Single Section Mode Locked Lasers for Photonic Integrated Circuits,” Opt. Express 22, 2014, pp. 11254–11266.
  36. A. A. Savchenkov et al., “Whispering-Gallery Mode Based Opto-Electronic Oscillators,” 2010 IEEE International Frequency Control Symposium, pp. 554–557.