Linewidth reduction of a distributed-feedback diode laser using an all-fiber interferometer with short path imbalance

Area of Science:

• Photonics and Laser Technology
• Optical Engineering

Background:

• Distributed-feedback (DFB) diode lasers are crucial light sources, but their free-running linewidth can limit applications.
• Achieving narrow linewidths typically requires complex and expensive stabilization techniques.

Purpose of the Study:

• To demonstrate a simple, cost-effective method for significantly reducing the linewidth of a DFB diode laser.
• To investigate the performance of an all-fiber interferometer for laser linewidth narrowing.

Main Methods:

• Utilized an all-fiber interferometer with a 5-m path imbalance to narrow the linewidth of a 1156 nm DFB diode laser.
• Evaluated optical power loss, bandwidth limitations, and frequency lock stability.
• Performed experiments without acoustic or vibration isolation.

Main Results:

• Reduced the free-running linewidth of the DFB laser from 3 MHz to 15 kHz.
• Observed negligible optical power loss and bandwidth limitations.
• Maintained frequency lock for over weeks without specialized isolation.

Conclusions:

• The all-fiber interferometer technique provides a simple, compact, robust, and cost-effective solution for narrow linewidth DFB lasers.
• This method is broadly applicable across various wavelengths due to the availability of DFB lasers and fiber components.
• The technique eliminates the need for acoustic and vibration isolation, simplifying experimental setups.