Narrow Linewidth Tunable DFB Laser Array Integrated With Optical Feedback Planar Lightwave Circuit (PLC)

A tunable distributed feedback (DFB) laser array integrated with a silica-based external optical feedback planar lightwave circuit is proposed and developed. The laser does not have high-resolution optical filters, and we can tune the wavelength over the entire C-band simply via laser selection and temperature control. The spectral linewidth is successfully reduced thanks to the optical feedback effect. Narrow linewidths of less than 10 kHz are obtained over the entire C-band.