64-channel InP-based laser array with lateral α-Si reconstruction equivalent chirp gratings

Multiple-wavelength laser arrays play important roles in various applications, such as optical communications, optical interconnections, as well as light detection and ranging. A 64-channel laser array with a wavelength grid of 0.8 nm at C+L band is demonstrated. The lasing modes in InP-based multiple quantum wells are built based on lateral α-Si Reconstruction Equivalent Chirp (REC) gratings. By introducing an equivalent λ/4 phase-shift in each lateral α-Si REC grating, the mode degeneracy is eliminated. The equivalent λ/4 phase-shift region has no influences on the zero-order peak but generates a sharp peak in the first order peak, selecting the lasing wavelength. When the seed grating period in lateral α-Si REC grating is fixed at 250 nm and the sampling periods are changed from 6.356 μm to 39.162 μm for 64 channels, the lateral α-Si REC gratings successfully select 64 wavelengths in C+L band at 0.8 nm wavelength interval. Utilizing the sampling periods with several hundred nanometers in the first order resonant peak, we can adjust a sequence of REC gratings more accurate than the seed grating periods with several nanometers in the zero-order resonant peak. The laser in 64-channel laser array with 0.8 nm channel spacing has a threshold of 42 mA, and output power of 74.5 mW. Our work proposes a novel method of multiple-wavelength laser arrays for hetero-integration, which could provide a potential way for the development of Wavelength Division Multiplexing (WDM) system, optical interconnection inside the data center, and photonic switching.