Enhancing laser temperature stability by passive self-injection locking to a microring resonator

Area of Science:

• Photonics and Optical Engineering
• Laser Physics
• Integrated Optics

Background:

• Maintaining laser frequency stability is crucial for many applications.
• Distributed feedback (DFB) lasers are widely used but can be sensitive to temperature fluctuations.
• Microring resonators offer precise frequency selection but require stable laser sources.

Purpose of the Study:

• To demonstrate a thermally stable self-injection locking technique for a DFB laser using a microring resonator.
• To improve the operational temperature range of the locked laser system.
• To investigate the remote locking capabilities of the system over extended fiber lengths.

Main Methods:

• Implemented a self-injection locking scheme where a DFB laser is locked to the resonance of a microring resonator.
• Incorporated optical amplification within the feedback loop to reduce the power required for locking.
• Introduced a 2.2 km fiber spool to test remote locking performance.

Main Results:

• Achieved a tenfold increase in the operational temperature range for maintaining laser frequency within 100 MHz of the target.
• Demonstrated reduced per-laser power requirements for locking due to the amplification in the feedback loop.
• Successfully validated remote locking performance over a 2.2 km fiber link.

Conclusions:

• The self-injection locked DFB laser-microring resonator system offers enhanced thermal stability and reduced power consumption.
• The system is suitable for remote laser frequency stabilization applications, even over significant distances.
• This technique provides a robust solution for applications requiring highly stable laser frequencies.