Experimental Demonstration of 150-Channel REC-DFB Laser Array Based on Asymmetric Multiple-Quantum-Well

We propose and demonstrate a 150-channel multi-wavelength distributed feedback (DFB) laser array for dense wavelength division multiplexing (DWDM) systems. The proposed multi-wavelength laser array with wavelength spacing at 0.8 nm (100 GHz) meets the ITU-T specifications. Using the reconstructed equivalent chirp (REC) technique, an equivalent $\pi $ phase shift is introduced at the center of the laser cavity to guarantee stable single longitudinal mode operation. Besides, the grating fabrication is simplified and the precision of the wavelength spacing is enhanced by the proposed REC technique. In addition, the asymmetric multiple-quantum-well (AMQW) technique is used to broaden the modal gain spectral, thus providing enough gain for all the wavelengths of interest. As a result, a 150-channel multi-wavelength DFB laser array is experimentally demonstrated. At the bias current of 120 mA, the side mode suppression ratios (SMSRs) of all the channels are above 45 dB. The lasing wavelengths are then linearly fitted and the fitted results indicate that the average channel spacing is 0.81 nm, which is only ±0.01 nm deviated from our design. All the 150 lasers operate with low threshold currents of 25 to 65 mA, which is owing to the broad wavelength range of gain provided by the AMQW structure. The output power of all the 150 lasers is over 10 mW at the bias current of200mA. The proposed laser array has a far-field divergence angle of $32^{\circ } \times 26^{\circ }$ and Lorentzian fitted linewidth of 3.35 MHz. To the best of our knowledge, the 150-channel multi-wavelength DFB laser array reported in this paper represents the highest number of channels for a DFB laser array reported to date. The superior properties of the proposed laser array such as stable single-mode operation, precise wavelength control, and high channel count are advantageous for its application in the DWDM systems to enhance the transmission capacity.