Spectral Characteristic Based on Fabry-Perot Laser Diode with Two-Stage Optical Feedback

Abstract

An optical device, consisting of a multi-mode Fabry-Perot laser diode (MMFP-LD) with two-stage optical feedback, is proposed and experimentally demonstrated. The results show that the single-mode output with side-mode suppression ratio (SMSR) of similar to 21.7dB is attained by using the first-stage feedback. By using the second-stage feedback, the SMSR of single-mode operation could be increased to similar to 28.5dB while injection feedback power of -29dBm is introduced into the laser diode. In the case of up to -29dBm feedback power, the outcome SMSR is rapidly decayed to a very low level so that an obvious multi-mode operation in the output spectrum could be achieved at the feedback power level of -15.5dBm. Thus, a transition between single- and multi-mode operations could be flexibly controlled by adjusting the injected power in the second-stage feedback system. Additionally, in the case of injection locking, the outcome SMSR and output power at the locked wavelength are as high as similar to 50dB and similar to 5.8dBm, respectively.