Integrated InP frequency discriminator for Phase-modulated microwave photonic links

[EN] We report the design, fabrication and characterization of an integrated frequency discriminator on InP technology for microwave photonic phase modulated links. The optical chip is, to the best of our knowledge, the first reported in an active platform and the first to include the optical detectors. The discriminator, designed as a linear filter in intensity, features preliminary SFDR values the range between 67 and 79 dB.Hz2/3 for signal frequencies in the range of 5-9 GHz limited, in principle, by the high value of the optical losses arising from the use of several free space coupling devices in our experimental setup. As discussed, these losses can be readily reduced by the use of integrated spot-size converters improving the SFDR by 17.3 dB (84-96 dB.Hz2/3). Further increase up to a range of (104-116 dB.Hz2/3) is possible by reducing the system noise eliminating the EDFA employed in the setup and using a commercially available laser source providing higher output power and lower relative intensity noise. Other paths for improvement requiring a filter redesign to be linear in the optical field are also discussed.The authors wish to acknowledge the financial support given by the Research Excellency Award Program GVA PROMETEO 2008/092, Spanish MICINN Project TEC2010-21337, acronym ATOMIC; project FEDER UPVOV10-3E-492 and project FEDER UPVOV08-3E008. J.S. Fandiño acknowledges financial support through grant FPU-2010 (ref: AP2010- 1595). J. D. Doménech acknowledges both Beca de Formacion de Personal Investigador (FPI) research grant (ref: BES-2009-018381) and funding from Intel Doctoral Student Honor Programme. The authors are also grateful to the EuroPIC consortium (FP7 funded programme NMP 228839-2) for access to the design manual and design toolkit of the generic InP fabSánchez Fandiño, JA.; Doménech Gómez, JD.; Muñoz Muñoz, P.; Capmany Francoy, J. (2013). Integrated InP frequency discriminator for Phase-modulated microwave photonic links. Optics Express. 21(3):3726-3736. https://doi.org/10.1364/OE.21.00372637263736213Capmany, J., & Novak, D. (2007). Microwave photonics combines two worlds. Nature Photonics, 1(6), 319-330. doi:10.1038/nphoton.2007.89LaGasse, M. J., & Thaniyavaru, S. (1997). Bias-free high-dynamic-range phase-modulated fiber-optic link. IEEE Photonics Technology Letters, 9(5), 681-683. doi:10.1109/68.588207Urick, V. J., Bucholtz, F., Devgan, P. S., McKinney, J. D., & Williams, K. J. (2007). Phase Modulation With Interferometric Detection as an Alternative to Intensity Modulation With Direct Detection for Analog-Photonic Links. IEEE Transactions on Microwave Theory and Techniques, 55(9), 1978-1985. doi:10.1109/tmtt.2007.904087McKinney, J. D., Colladay, K., & Williams, K. J. (2009). Linearization of Phase-Modulated Analog Optical Links Employing Interferometric Demodulation. Journal of Lightwave Technology, 27(9), 1212-1220. doi:10.1109/jlt.2008.929409Haas, B. M., Urick, V. J., McKinney, J. D., & Murphy, T. E. (2008). Dual-Wavelength Linearization of Optically Phase-Modulated Analog Microwave Signals. Journal of Lightwave Technology, 26(15), 2748-2753. doi:10.1109/jlt.2008.925656Darcie, T. E., Zhang, J., Driessen, P. F., & Eun, J.-J. (2007). Class-B Microwave-Photonic Link Using Optical Frequency Modulation and Linear Frequency Discriminators. Journal of Lightwave Technology, 25(1), 157-164. doi:10.1109/jlt.2006.888173Xie, X., Khurgin, J. B., Kang, J. U., & Choa, F. S. (2002). Compact linearized optical FM discriminator. IEEE Photonics Technology Letters, 14(3), 384-386. doi:10.1109/68.986821Wyrwas, J. M., & Wu, M. C. (2009). Dynamic Range of Frequency Modulated Direct-Detection Analog Fiber Optic Links. Journal of Lightwave Technology, 27(24), 5552-5562. doi:10.1109/jlt.2009.2031986Marpaung, D., Roeloffzen, C., Leinse, A., & Hoekman, M. (2010). A photonic chip based frequency discriminator for a high performance microwave photonic link. Optics Express, 18(26), 27359. doi:10.1364/oe.18.027359Wyrwas, J. M., Peach, R., Meredith, S., Middleton, C., Rasras, M. S., Tu, K.-Y., … DeSalvo, R. (2012). Linear phase-and-frequency-modulated photonic links using optical discriminators. Optics Express, 20(24), 26292. doi:10.1364/oe.20.026292Rasras, M. S., Chen, Y.-K., Tu, K.-Y., Earnshaw, M. P., Pardo, F., Cappuzzo, M. A., … DeSalvo, R. (2012). Reconfigurable Linear Optical FM Discriminator. IEEE Photonics Technology Letters, 24(20), 1856-1859. doi:10.1109/lpt.2012.2217483Besse, P. A., Gini, E., Bachmann, M., & Melchior, H. (1996). New 2×2 and 1×3 multimode interference couplers with free selection of power splitting ratios. Journal of Lightwave Technology, 14(10), 2286-2293. doi:10.1109/50.541220Gasulla, I., & Capmany, J. (2011). Analytical model and figures of merit for filtered Microwave photonic links. Optics Express, 19(20), 19758. doi:10.1364/oe.19.01975