Tunable Dual-Wavelength Self-injection Locked InGaN/GaN Green Laser Diode

Abstract

We implemented a tunable dual-longitudinal-mode spacing InGaN/GaN green (521-528 nm) laser diode by employing a self-injection locking scheme that is based on an external cavity configuration and utilizing either a high or partial-reflecting mirror. A tunable longitudinal-mode spacing of 0.20 -5.96 nm was accomplished, corresponding to a calculated frequency difference of 0.22-6.51 THz, as a result. The influence of operating current and temperature on the system performance was also investigated with a measured maximum side-mode-suppression ratio of 30.4 dB and minimum dual-mode peak optical power ratio of 0.03 dB. To shed light on the operation of the dual-wavelength device arising from the tunable longitudinal-mode spacing mechanism, the underlying physics is qualitatively described. To the best of our knowledge, this tunable longitudinal-mode-spacing dual-wavelength device is novel, and has potential applications as an alternative means in millimeter wave and THz generation, thus possibly addressing the terahertz technology gap. The dual-wavelength operation is also attractive for high-resolution imaging and broadband wireless communication.

Single/Multi-wavelength green laser diode system

“…2 (c). The emission wavelengths and the mode spacing of the locked modes can be tuned by varying the length of the external cavity, injection current, and temperature of the system [2,3].…”