Enhanced feedback sensitivity suppression in phase-detuned tunable lasers with high-Q Vernier-effect based ring...

Area of Science:

• Photonics and Laser Technology
• Optical Engineering
• Semiconductor Lasers

Background:

• External optical feedback can degrade the performance of semiconductor lasers, increasing relative intensity noise (RIN).
• Tunable lasers are crucial for applications like optical communications, but their sensitivity to feedback remains a challenge.
• Ring resonator structures offer high wavelength selectivity and can be used to control laser feedback.

Purpose of the Study:

• To investigate the feedback sensitivity of a tunable laser employing a Vernier-effect ring resonator reflector.
• To demonstrate methods for reducing feedback sensitivity and improving laser performance under optical feedback.
• To evaluate the high-speed data transmission capabilities of the modified tunable laser.

Main Methods:

• Experimental characterization of a tunable laser integrated with a high-Q Vernier-effect ring resonator.
• Simulation work to analyze the laser's behavior under varying feedback conditions and detuning.
• Measurement of relative intensity noise (RIN) and assessment of data transmission performance.

Main Results:

• Tuning the amplitude and phase of the ring resonator reflector significantly reduces feedback sensitivity.
• Red detuning suppresses excess RIN to feedback levels above -13 dB, a 5 dB improvement over non-detuned lasers.
• The red-detuned ring resonator tunable laser demonstrates enhanced stability against feedback during high-speed data transmission.

Conclusions:

• Vernier-effect ring resonator structures provide an effective means to mitigate optical feedback issues in tunable lasers.
• Phase-detuned tunable lasers with reduced feedback coefficients outperform traditional distributed Bragg reflector (DBR) lasers.
• The developed tunable laser exhibits superior stability and performance for optical communication systems susceptible to feedback.