Ultrawideband precise tunable wavelength-locked laser based on high-density integrated distributed feedback laser array.

We developed and experimentally demonstrated an ultrawideband, precisely tunable wavelength-locked distributed feedback (DFB) laser array in an 8 × 4 matrix with a wavelength tuning range of 80 nm. The reconstruction equivalent chirp technique was applied to simplify grating fabrication and enhance the precise control of wavelength spacing. A cascaded Y-branch sharing an identical active layer with the lasers enabled a one-waveguide output, requiring a small current to compensate for material absorption and thus reducing the fabrication complexity compared with butt coupling. A semiconductor optical amplifier was integrated in front of the laser array to amplify and adjust the optical power. Statistical tests were performed on 640 DFB laser units from 20 randomly selected DFB laser arrays. The results showed that the wavelength of the laser array was precisely controlled, with more than 94% of the DFB laser units having a wavelength deviation within ±0.2 nm. Over 97% of the DFB laser units had a side-mode suppression ratio exceeding 40 dB. The relative intensity noise of all DFB laser units was below -130 dB/Hz. By introducing a wavelength-locked and feedback control system based on Fabry-Perot etalon, the proposed DFB laser array achieved full-band wavelength tuning accuracy within 2 pm without adjusting the thermoelectric cooler for tuning in less than 250 µs. Additionally, wavelength drift caused by changes in thermal equilibrium remained below 10 pm during high- and low-temperature tests ranging from -10 to 70 °C. The proposed wideband wavelength-locked laser is promising for future data centers, metropolitan transmission systems, and access networks based on dense wavelength division multiplexing.