Nano-ITLA Based on Thermo-Optically Tuned Multi-Channel Interference Widely Tunable Laser

A tunable light source with narrow linewidth, small size and low power consumption is necessary for high-speed digital coherent communication system. We have developed a monolithically integrated narrow linewidth widely tunable laser—multi-channel interference (MCI) laser, which realizes a quasi-continuous tuning range covering the C++ band. By packaging the laser chip, wavelength locker and thermoelectric cooler (TEC) into a transmitter optical subassembly (TOSA) box and designing a compact print circuit board (PCB), a nano-integrable tunable laser assembly (Nano-ITLA) based on the thermo-optically tuned MCI laser is demonstrated for the first time. The Nano-ITLA is 25.0 mm (L) × 15.6 mm (W) × 6.5 mm (H), and realizes 120 International Telecommunication Union (ITU)-grid switching over 48 nm and less than 3 W total power consumption. The side-mode suppression ratios (SMSRs) are higher than 46 dB, the fiber coupled output powers are greater than 16 dBm, and the Lorentzian linewidths are less than 150 kHz. High precision wavelength locking and temperature control system make the output frequency deviation of all channels from the ITU-grid less than ±0.5 GHz and the wavelength drift less than ±1 pm. The output power can be accurately controlled and stabilized at ±0.1 dB through a closed-loop feedback. The no-light shutdown function realizes an extinction ratio higher than 40 dB during wavelength switching. The Nano-ITLA demonstrates excellent application potential in the coherent optical communications.