Single Output Tunable DFB Semiconductor Laser Array with Equivalent Phase Shift

An integrated parity-time symmetric wavelength-tunable single-mode microring laser

“…At present, there are four major approaches that have been extensively studied for mode management in a laser cavity. The first approach is to use optical feedback in a cavity to achieve single-mode operation 4 5 6 ; the second is to enhance mode confinement by reducing the mode size in a laser cavity to achieve single-mode operation 7 8 9 ; the third is to shape the spatial profile of a pump light to a laser cavity to achieve mode selection 10 ; and the fourth approach is to use parity-time (PT) symmetry 11 12 13 14 15 16 to implement mode selection. The last approach has been an active topic and has been heavily researched recently 17 18 19 20 21 .…”

“…An ultrashort cavity (∼5.5 μm) with a large free spectral range (FSR) offers strong mode selectivity for single-mode lasing 4 . A DFB laser has an active region containing a periodically structured grating to provide a strong optical feedback for a single longitudinal mode operation, in which tunable operating wavelength is possible by thermal tuning 6 . However, the cavity feedback structure in a DFB laser is complicated and the use of such a structure would increase the fabrication complexity.…”