Sideband locking of a single-section semiconductor distributed-feedback laser in an optical phase-lock loop

Area of Science:

• Photonics
• Optical Engineering
• Laser Physics

Background:

• Optical phase-lock loops (OPLLs) are crucial for precise frequency control in optical systems.
• Single-section semiconductor lasers (SCLs) exhibit nonuniform frequency modulation (FM) responses, limiting OPLL performance.
• Existing OPLLs struggle with achieving wide bandwidths due to laser FM nonlinearities.

Purpose of the Study:

• To overcome the bandwidth limitations of OPLLs caused by SCLs' nonuniform FM response.
• To demonstrate a novel sideband locking technique for enhanced OPLL performance.
• To characterize the output lineshape of a phase-locked SCL.

Main Methods:

• Implementing a heterodyne OPLL configuration.
• Utilizing sideband locking of a single-section distributed-feedback SCL to a master laser.
• Employing delayed self-heterodyne measurements to analyze the SCL output lineshape.

Main Results:

• The sideband locking technique successfully eliminated the FM response restriction in the OPLL.
• A delay-limited loop bandwidth was achieved, significantly improving performance.
• The lineshape of the phase-locked SCL output was successfully characterized.

Conclusions:

• Sideband locking is an effective method to enhance OPLL bandwidth and performance.
• This technique enables OPLLs to reach their theoretical delay-limited bandwidth.
• The characterization of the phase-locked SCL output provides insights into laser dynamics.