Physics

Laser linewidth

Laser

Resonator

Injection locking

Optics

Semiconductor laser theory

Injection seeder

Fiber laser

Optical cavity

Materials science

Laser power scaling

Fiber Bragg grating

Longitudinal mode

Optoelectronics

Distributed feedback laser

Optics Express

Self-injection locking to an external fiber cavity is an efﬁcient technique enabling drastic linewidth narrowing and self-stabilization of semiconductor lasers. The main drawback of this technique is its high sensitivity to fluctuations of the configuration parameters and surroundings. In the proposed laser configuration, to the best our knowledge, for the first time the self-injection locking mechanism is used in conjunction with a simple active optoelectronic feedback, ensuring stable mode-hopping free laser operation in a single longitudinal mode. Locking to 4-m length fiber resonator causes a drastic narrowing of the DFB laser linewidth down to 2.8 kHz and a reduction of the laser phase noise by three orders of magnitude. We have explored key features of the laser dynamics with and without active feedback, revealing stability and tunability of the laser linewidth as an additional benefit of the proposed technique.

Stabilizing DFB laser injection-locked to an external fiber-optic ring resonator