Optical Sideband Injection Locking Using Waveguide Based External Cavity Semiconductor Lasers for Narrow-Line, Tunable Microwave Generation

The generation by optical injection locking of spectrally unadulterated microwave signals using waveguide based external cavity semiconductor lasers (WECSL) is demonstrated. A tunable frequency of 2–11 GHz, limited by the modulator’s bandwidth and the photodetector (PD), was created as proof-of-experiment by the injection locking of the two WESCLs. A single sideband (SSB) phase noise of −75 dBc/Hz from the generated carrier at 10 kHz offset and a phase noise variance at an optimum injection ratio region was 0.03 rad2, corresponding to 1.7°, were observed. The main feature of this approach is the consolidation of the upsides of microwave generation at low phase noise with a broad tuning range and the capacity of hybrid photonic integration. In addition, the injection locking characteristics were used to determine the Q factor of the complicated optical cavities with unknown inner losses.

Study of the characteristics of 976 nm Bragg grating external cavity semiconductor lasers

976 nm fiber Bragg grating (FBG) external cavity laser is the core component in erbium-doped fiber amplifiers (EDFA). In this paper, the theory model of FBG is modeled by transfer matrix method (TMM). The effects of Bragg grating length and modulation depth on the reflectivity, grating spectrum width and wavelength have been investigated. Then 976 nm laser modules with different grating reflectivity, i.e. 4%, 6%, 8% and 10% have been fabricated. By improving the reflectivity of FBG, the side-mode suppression ratio (SMSR) has been optimized to above 40 dB, and the threshold current decreases. The temperature cycling test indicates that the peak wavelength has a change rate [Formula: see text]0.0095 nm/[Formula: see text]C.