Optical Injection Locking – pushing the limit of high speed optoelectronics

Students: Devang Parekh, Weijian Yang

Optical injection locking (OIL) of semiconductor lasers has been demonstrated as an efficient and robust technique to improve the spectral and dynamic performance of a directly modulated diode laser. Optical injection locking refers to a state when the frequency and phase of a laser, usually referred to as the slave laser, are locked via optical injection by another laser, commonly referred to as the master laser. For VCSELs, however, we show that modulation and transmission characteristics can be greatly improved by OIL.

Optically injection locking of VCSELs is especially promising since VCSELs emit low optical power and single longitudinal mode over a wide spectral range. These are essential ingredients for effective injection locking. We have experimentally shown a more than 100 GHz resonant frequency and an 80 GHz intrinsic 3 dB bandwidth of OIL-VCSELs [1], transmission distance extension for high-data rate modulation by chirp inversion and reduction [2, 3], multi-Gbps millimeter-wave radio-over fiber [4], optoelectronic oscillator for ultra-low phase noise frequency generation [5], WDM-PON [6], and multimode to singlemode conversion using optical injection locking [3]. Moreover, we have modeled the OIL VCSEL using interferometric [7] and graphical models [8] of the laser dynamics. Experiments for using OIL VCSELs for advanced modulation formats are currently underway.

Selected Publications:

1. E. K. Lau, X. Zhao, H. K. Sung, D. Parekh, C. Chang-Hasnain, and M. C. Wu, “Strong optical injection-locked semiconductor lasers demonstrating > 100-GHz resonance frequencies and 80-GHz intrinsic bandwidths,” Opt. Express 16, 6609–6618 (2008).
2. X. Zhao, B. Zhang, L. Christen, D. Parekh, W. Hofmann, M. C. Amann, F. Koyama, A. E. Willner, and C. J. Chang-Hasnain, “Greatly increased fiber transmission distance with an optically injection-locked vertical-cavity surface-emitting laser,” Opt. Express 17(16), 13785–13791 (2009).
3. D. Parekh, B. Zhang, X. Zhao, Y. Yue, W. Hofmann, M. C. Amann, A. E. Willner, and C. J. Chang-Hasnain, “Long distance single-mode fiber transmission of multimode VCSELs by injection locking,” Opt. Express 18, 20552-20557 (2010).
4. A. Ng'oma, D. Fortusini, D. Parekh, W. Yang, M. Sauer, S. Benjamin, W. Hofmann, M. C. Amann, and C. J. Chang-Hasnain, "Performance of a Multi-Gb/s 60 GHz Radio Over Fiber System Employing a Directly Modulated Optically Injection-Locked VCSEL," J. Lightwave Technol. 28, 2436-2444 (2010).
5. H.-K. Sung, X. Zhao, E. K. Lau, D. Parekh, C. J. Chang-Hasnain, and M. C. Wu, "Optoelectronic Oscillators Using Direct-Modulated Semiconductor Lasers Under Strong Optical Injection," IEEE J. Sel. Topics Quantum Electron., 15, 572-577 (2009).
6. E. Wong, X. Zhao, C. J. Chang-Hasnain, W. Hofmann, and M. C. Amann, "Applications of 1.55 μm optically injection-locked VCSELs in wavelength division multiplexed passive optical networks," Proc. of SPIE, 6783, 67832M, (2007).
7. W. Yang, P. Guo, D. Parekh, and C. J. Chang-Hasnain, "Reflection-mode optical injection locking," Opt. Express 18, 20887-20893 (2010).
8. P. Guo, W. Yang, D. Parekh and C. J. Chang-Hasnain, "A novel ellipse model for optically injection-locked VCSELs," Frontiers in Optics, San Jose, CA, 2009.