Impact Statement:
In regards to wireless communications low noise optical alternatives to electronic signal generation are sought after. Photomixing two laser signal to generate THz signals is a well know way of such alternatives. The goal is to achieve lower noise than the electronic counterpart. We investigated optical injection locking in DR type lasers to minimize noise. The initial question of which laser architecture is best suited for optical injection locking for lowest noise operation has been investigated and a conclusion was derived.
Complex coupled distributed feedback (DFB) lasers and sampled grating distributed Bragg reflector (SGDBR) lasers under optical injection locking are investigated to determine lowest noise operation. A noise reduction (frequency and intensity combined) of up to 15 dB was measured utilizing detuned optical injection locking at the relaxation oscillation frequency. Furthermore, 4 dB improvement in frequency noise at 10 kHz offset for higher coupling coefficient DFBs under injection locking was measured. The DFB lasers show more sensitivity to injection locking and have a lower need of injection power while exhibiting better signal to noise ratio compared to an SGDBR.
Published in: IEEE Journal of Quantum Electronics ( Volume: 60, Issue: 4, August 2024)
