Low-threshold and high-speed 1.5-µm strained-layer multiple quantum-well four-wavelength distributed-feedback laser arrays

Abstract

In light-wave communication systems the information capacity through optical fibers can be increased by wavelength-division multiplexing.¹ Distributed-feedback (DFB) laser arrays are compact for such applications. Previously, a 20-DFB laser array with a threshold current of 15-20 mA that operated around 15 µm over a wavelength span of 20 nm² has been reported. Recently, a 1.5-µm 4-distributed Bragg reflector laser array integrated with a power combiner and an optical amplifier has been used in a 2-Gb/s system experiment.³ In the latter case, degradation in receiver sensitivity owing to the cross talk from the neighboring lasers was observed. For a laser array a low threshold current is most important for minimizing the power consumption on the chip and the cross talk between lasers. Recently, we reported submilliampere-threshold lasers at the 1.5-µm wavelength by the use of biaxial strain and quantum confinement.⁴