Frequency stabilization of semiconductor lasers by resonant optical feedback

Area of Science:

• Optics
• Laser Physics
• Semiconductor Devices

Background:

• Semiconductor lasers often exhibit broad frequency linewidths.
• Stabilizing laser frequency is crucial for precision applications.
• Optical feedback methods offer potential for laser frequency control.

Purpose of the Study:

• To investigate the use of a Fabry-Perot cavity for semiconductor laser frequency stabilization.
• To demonstrate linewidth reduction in semiconductor lasers using optical feedback.

Main Methods:

• Utilized a separate resonant Fabry-Perot cavity as an optical feedback element.
• Configured simple optical geometries to couple the cavity to the semiconductor laser.
• Monitored laser frequency and linewidth before and after implementing the feedback system.

Main Results:

• Achieved automatic optical locking of the semiconductor laser frequency to the cavity resonance.
• Reduced laser linewidth by a factor of approximately 1000.
• Narrowed the linewidth from an initial 20 MHz to approximately 20 kHz.

Conclusions:

• A Fabry-Perot cavity is an effective optical feedback element for stabilizing semiconductor laser frequencies.
• This technique significantly reduces laser linewidth, improving spectral purity.
• The method offers a practical approach to enhance semiconductor laser performance.