High channel count and high precision channel spacing multi-wavelength laser array for future PICs

TLDR

Multi‑wavelength semiconductor laser arrays (MLAs) are widely used in wavelength‑division multiplexing networks, yet their adoption is limited by wavelength precision and fabrication cost. This paper reports high‑channel‑count MLAs whose channel wavelengths can be precisely determined using low‑cost μm‑level photolithography/holographic lithography combined with the reconstruction‑equivalent‑chirp technique. The arrays are fabricated with standard μm‑level photolithography/holographic lithography and the reconstruction‑equivalent‑chirp technique to achieve precise wavelength control. Experimental results show 60‑wavelength MLAs with ~83 % of lasers within ±0.20 nm deviation and a single‑longitudinal‑mode yield of nearly 100 %, far surpassing the ~33 % yield of conventional DFB lasers.

Abstract

Multi-wavelength semiconductor laser arrays (MLAs) have wide applications in wavelength multiplexing division (WDM) networks. In spite of their tremendous potential, adoption of the MLA has been hampered by a number of issues, particularly wavelength precision and fabrication cost. In this paper, we report high channel count MLAs in which the wavelengths of each channel can be determined precisely through low-cost standard μm-level photolithography/holographic lithography and the reconstruction-equivalent-chirp (REC) technique. 60-wavelength MLAs with good wavelength spacing uniformity have been demonstrated experimentally, in which nearly 83% lasers are within a wavelength deviation of ±0.20 nm, corresponding to a tolerance of ±0.032 nm in the period pitch. As a result of employing the equivalent phase shift technique, the single longitudinal mode (SLM) yield is nearly 100%, while the theoretical yield of standard DFB lasers is only around 33.3%.