1.3 μm wavelength tunable single-mode laser arrays based on slots

Abstract

Two twelve-channel arrays based on surface-etched slot gratings, one with non-uniformly spaced slots and another with uniformly spaced slots are presented for laser operation in the O-band. A wavelength tuning range greater than 40 nm, with a side-mode suppression ratio (SMSR) > 40 dB over much of this range and output power greater than 20 mW, was obtained for the array with non-uniform slots over a temperature range of 15 °C - 60 °C. The introduction of multiple slot periods, chosen such that there is minimal overlap among the side reflection peaks, is employed to suppress modes lasing one free spectral range (FSR) from the intended wavelength. The tuning range of the array with uniformly spaced slots, on the other hand, was found to be discontinuous due to mode-hopping to modes one FSR away from the intended lasing mode which are not adequately suppressed. Spectral linewidth was found to vary across devices with the lowest measured linewidths in the range of 2 MHz to 4 MHz.

Tunable quantum cascade lasers for midinfrared spectroscopic sensing

“…The slots are etched on the ridge surface of front and back sections with different periods to introduce the Vernier effect between the reflections from the two sections. In the development of slot waveguide laser, the facet phase effect remains a non-negligible issue [50,122,123]. As discussed in Ref .…”

“…In order to make sure of a wide continuous tuning range free of gaps, the supermodes of each individual emitter need to be designed lasing at distinct wavelengths, and the spacing between the supermodes from different lasers should be sufficiently small so that any wavelengths within the designed range could be covered through the continuous tuning. The supermode wavelength of a slot waveguide QCL can be expressed as [123]:…”