Discretely Tunable Semiconductor Lasers Suitable for Photonic Integration

Abstract

Abstract-A sequence of partially reflective slots etched into an active ridge waveguide of a 1.5 µm laser structure is found to provide sufficient reflection for lasing. Mirrors based on these reflectors have strong spectral dependence. Two such active mirrors together with an active central section are combined in a Vernier configuration to demonstrate a tunable laser exhibiting 11 discrete modes over a 30 nm tuning range with mode spacing around 400 GHz and side-mode suppression ratio larger than 30 dB. The individual modes can be continuously tuned by up to 1.1 nm by carrier injection and by over 2 nm using thermal effects. These mirrors are suitable as a platform for integration of other optical functions with the laser. This is demonstrated by monolithically integrating a semiconductor optical amplifier with the laser resulting in a maximum channel power of 14.2 dBm from the discrete modes.

Integrable Slotted Single-Mode Lasers

“…An exception is the slotted laser reported in [6][7][8][9][10][11][12][13]. These lasers use optical defects in a standard Fabry-Pérot (FP) laser to specifically select a single mode, and such optical defects are formed by etching around 1 µm wide slots into the top ridge of the laser waveguide.…”

Regrowth-free single-mode semiconductor laser suitable for monolithic integration based on pits mirror

“…These lasers achieve single-mode operation using various approaches, such as coupled cavities 9,10 and multiple semiconductor ring lasers, 11,12 or exploit mini reflections from index perturbation to create subcavities, such as slotted Fabry-Perot (SFP) lasers. [13][14][15] They provide a high side-mode suppression ratio (SMSR) that can exceed 40 dB, a wide tuning range covering the C + L bands, fine tuning step <21 pm∕mA, 16 and output power over 25 mW. 14 Moreover, in addition to their relatively simple fabrication process, they provide a narrow linewidth that has become a necessity for high spectral density, coherent optical communications.…”

“…[13][14][15] They provide a high side-mode suppression ratio (SMSR) that can exceed 40 dB, a wide tuning range covering the C + L bands, fine tuning step <21 pm∕mA, 16 and output power over 25 mW. 14 Moreover, in addition to their relatively simple fabrication process, they provide a narrow linewidth that has become a necessity for high spectral density, coherent optical communications. 17,18 This low linewidth is generated without the need of an external cavity, 19 complicated feedback system, 20 or dramatic increase in the cavity length as is typically required for DFB lasers to bring the linewidth down from a few MHz to the kHz regime.…”

“…It is clear that there is a growing need for low-cost, compact, and narrow linewidth lasers that can be used in monolithic integration with other optical and optoelectronics components, such as modulators, amplifiers, and photodiodes. 14,[21][22][23] In this paper, we demonstrate a regrowth-free higher order DBR laser process that does not require high-resolution photolithography. Mode selectivity is attained using a compact mirror with a length of 170 μm consisting of 1 μm × 1 μm deeply etched and closely spaced pits.…”

Nine-channel wavelength tunable single mode laser array based on slots

“…Tunable lasers based on surface gratings have also been demonstrated, which has the cost advantages due to its simple process [5,6] compared with the conventional buried DBR based lasers.…”