Multi-Wavelength DFB Laser Based on Sidewall Third Order Four Phase-Shifted Sampled Bragg Grating with Uniform Wavelength Spacing

TL;DR

This paper demonstrates a novel multi-wavelength DFB laser with uniform wavelength spacing using sidewall third-order sampled gratings and multiple phase shifts, suitable for dense wavelength division multiplexing systems.

Contribution

It introduces a simplified fabrication process for multi-wavelength DFB lasers with uniform spacing using sidewall gratings and multiple phase shifts.

Findings

Achieved stable four-wavelength operation with 0.4 nm spacing.

Demonstrated seven-channel laser with 0.274 nm spacing.

Simplified manufacturing process with single MOVPE step.

Abstract

We present the first demonstration of a 1550 nm multi-wavelength distributed feedback (MW-DFB) laser employing a third-order, four-phase-shifted sampled sidewall grating. By utilizing linearly chirped sampled gratings and incorporating multiple true {\pi}-phase shifts within the cavity, we achieved and experimentally validated a four-wavelength laser with a channel spacing of 0.4 nm. The device operates stably and uniformly across a wide range of injection currents from 280 mA to 350 mA. The average wavelength spacing was measured at 0.401 nm with a standard deviation of 0.0081 nm. Additionally, we demonstrated a 0.3 nm MW-DFB laser with a seven-channel output, achieving a wavelength spacing of 0.274 nm and a standard deviation of 0.0055 nm. This MW-DFB laser features a ridge waveguide with sidewall gratings, requiring only one metalorganic vapor-phase epitaxy (MOVPE) step and a single III-V material etching process. This streamlined fabrication approach simplifies device manufacturing and is well-suited for dense wavelength division multiplexing (DWDM) systems.