Study on InP-based DFB semiconductor laser with dual-transverse mode hybrid resonance

A three-section dual-transverse mode hybrid resonant laser has been successfully developed on the InP platform, utilizing a 2D sampling grating. This laser comprises an active section with a π phase-shifted anti-symmetric Bragg grating (π-ASBG) and two passive sections with uniform Bragg gratings (UBGs). With this design, it enables the simultaneous and stable emission of both the fundamental transverse electric mode (TE0) and the first-order transverse electric mode (TE1). The physical mechanism of dual-transverse mode hybrid resonance in the cavity of a semiconductor laser is analyzed, based on the coupled-mode theory. The experimental results indicate that the laser consistently maintains an output wavelength of 1549 nm, achieving side-mode suppression ratios (SMSR) of 38 dBand30 dB, respectively, under the emission of the TE0 mode and the TE1 mode. Therefore, as the transverse mode tunable light source, the laser may benefit the future mode division multiplexing (MDM) systems for more reconfigurability and flexibility.