DFB laser array based on four phase-shifted sampled Bragg gratings with precise wavelength control

Abstract

A four-laser array based on sampled Bragg grating distributed feedback (DFB) lasers in which each sampled period contains four phase-shift sections is proposed, fabricated, and experimentally demonstrated. The wavelength spacing between adjacent lasers is accurately controlled to 0.8 nm ± 0.026 nm and the lasers have single mode suppression ratios larger than 50 dB. Using an integrated semiconductor optical amplifier, the output power can reach 33 mW and the optical linewidth of the DFB lasers can be as narrow as 64 kHz. This laser array uses a ridge waveguide with sidewall gratings and needs only one metalorganic vapor-phase epitaxy (MOVPE) step and one III-V material etching process, simplifying the whole device fabrication process, and meeting the requirements of dense wavelength division multiplexing systems.

Millimeter-Wave Generation Based on Four Phase-Shifted Sampled Moiré Grating Dual-Wavelength DFB Laser

“…The detailed fabrication process can be found in [9]. The completed chip was cleaved into bars, soldered to a copper sub-mount using indium, and characterized under continuous wave (CW) conditions at 20 °C.…”

“…Therefore, the mathematical form of the refractive index modulation of the +1 st order sub-grating in SMG becomes an envelope function with the rapid changing component having a period of Λs and the slowly changing envelope a period of Λc. In addition, the equivalent refractive index creates a πphase shift where the cosine variation of the envelope meets a crossover [9]. Fig.…”

“…Dual-wavelength lasers (DWLs) have been reported using different grating modulation schemes such as chirp and apodization [7,8]. In addition, Sampled Bragg grating based on reconstructed equivalent chirp (REC) technology has also been proposed and utilized in DWLs [9]. These methods require two actual and tangible π phase shifts to enable dual-mode lasing.…”

Dual-wavelength DFB Laser Based on Four Phase-shifts Sections and Equivalent Chirp Technology for Millimeter-wave Generation

“…Dual-wavelength lasing is achieved by introducing two π phase shifts at positions 1/3 and 2/3 along the length of the DFB laser cavity [1]. Compared to conventional sampled Bragg gratings, the 4PS sampling structure has a higher grating coupling coefficient, κ, for the +1 st channel, with κ equal to 0.9 times that of a uniform seed grating [2,3]. Meanwhile, the equivalent chirp technology is applied by linearly modulating the sampling periods along the DFB cavity, thus ensuring the peaks in the photon distributions of the two lasing modes at separate locations along the cavity.…”