A Low-Cost Hybrid Integrated Narrow Linewidth Laser Based on REC and PWB Techniques

A low-cost hybrid integrated narrow linewidth laser is proposed in this paper. The monolithically integrated 18- channel distributed feedback (DFB) narrow linewidth laser array with a wavelength interval of 0.8 nm is designed and precisely fabricated using reconstruction equivalent chirp (REC) technique, exhibiting good single-mode performance for each channel, with the typical linewidth less than 200 kHz. One channel of the laser array is integrated with the silicon nitride (Si<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>N<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub>) external cavity chip through the photonic wire bonding (PWB) technique. Both the linewidth reduction effect of the passive external cavity and the coupling efficiency between chips by the polymer waveguide are numerically calculated. The compactly packaged device can be tuned to seven distinct self-injection-locked states with 0.4 nm spectral spacing, where the maximum linewidth is 10.9 kHz and the minimum linewidth is 9.1 kHz. Meanwhile, the side-mode suppression ratio (SMSR) is higher than 54.3 dB and the output power is 3.6 ± 0.9 dBm for each self-injection-locked state.