Optical Injection Locking
Constance Chang-Hasnain, Xiaoxue Zhao, Devang Parekh, Ming C. Wu and Erwin K. Lau
The great achievements on both digital and analog fiber-optic communications have shown their powerful functions and significant effects on our everyday life. Semiconductor optoelectronics is the major enabling component in optical communications, and has become a wide and vast research field. Direct modulated lasers, as optical transmitters in a fiber-optic communication system, are cost-effective and compact. High performance of a direct modulated semiconductor laser is highly desirable in both analog and digital links. One method that can drastically improve the performance of a direct modulated laser is optical injection locking (OIL), which uses a second laser (master laser) to inject photons at a similar wavelength into the transmitter laser (follower laser). The transmitter laser is thus locked (in wavelength and phase) to the master due to the coherent non-linear interaction.
Optical injection locking is also applied to obtain slow light effect in semincoductor lasers, which can be potentially used for optical buffers, as well as optoelectronic oscillators (OEO), which can generate low phase noise and high-frequency microwave signals.