Hybrid integrated narrow-linewidth semiconductor lasers

Integrated narrow-linewidth lasers are the key devices in compact coherent optical systems of metrology, sensing, and optical microwave generation. Here, we demonstrate a hybrid integrated laser based on an optical negative feedback scheme. The laser is composed of a commercial distributed feedback (DFB) laser diode and an on-chip micro-resonator with a Q-factor of 0.815 million. The feedback optical field is coupled back to the laser cavity through the back facet. Therefore, the laser can maintain the lasing efficiency of the DFB laser diode. The linewidth of the DFB laser diode is compressed from 2 MHz to 6 kHz, corresponding to the linewidth reduction factor of 25.2 dB. The theoretical result shows that the laser performance still has a huge improvement margin through precise control of the detuning between laser frequency and the micro-resonator, as well as the phase delay of the feedback optical field. The hybrid narrow-linewidth laser diode has wide application prospects in coherent optical systems benefitting from the low cost and volume productivity.(c) 2023 Optica Publishing Grouphttps://doi.org/10.1364/AO.486492

Automated summary

We demonstrate a hybrid integrated laser based on an optical negative feedback scheme, which consists of a commercial distributed feedback (DFB) laser diode and an on-chip micro-resonator with a Q-factor of 0.815 million. By coupling the feedback optical field back to the laser cavity through the back facet, the laser maintains the lasing efficiency of the DFB laser diode and compresses its linewidth from 2 MHz to 6 kHz, corresponding to a linewidth reduction factor of 25.2 dB. Theoretical analysis suggests that precise control of the detuning between laser frequency and the micro-resonator, as well as the phase delay of the feedback optical field, could further improve the laser performance. This hybrid narrow-linewidth laser diode has wide application prospects in coherent optical systems due to its low cost and high volume productivity.