Single mode emitting ridge waveguide quantum cascade lasers coupled to an active ring resonator filter

Abstract

Quantum cascade ridge waveguide lasers with coupled ring resonators have been fabricated. Coupling of an actively pumped microring resonator to a ridge waveguide device allows for filtering the numerous Fabry–Pérot modes emerging in the ridge waveguide. Due to the large free spectral range of the ring resonators mode selection is accomplished, resulting in stable single mode emission for an optimized design. Thus, side mode suppression ratios of up to 26 dB over a temperature range of 140 K are attained by on-chip coupling of a ridge waveguide device with a microsquare ring resonator. The tuning rate of the microring resonator laser is 0.40 nm/K. Output powers of several milliwatts are obtained.

Single-mode quantum cascade lasers employing a candy-cane shaped monolithic coupled cavity

“…An alternative approach is to employ monolithic coupled-cavity structures to facilitate single-mode operation. [7][8][9][10][11] Such cavities are more robust than conventional cleaved facet coupled-cavities; however, the structuring of inter-cavity mirrors or micro-resonators involves demanding fabrication steps such as focused ion beam cutting, electron-beam lithography, and/or high quality dry-etching. Previously, we have demonstrated single-mode QC lasers employing a hairpin shaped folded FP cavity 12 which is essentially a monolithic coupledcavity fully compatible with simple ridge laser fabrication.…”

Monolithically Integrated Mid-Infrared Quantum Cascade Laser and Detector

“…DFB arrays are perfect for in-plane on-chipsensing, where the surface emitting rings have the advantage a smaller divergence < 3 ° and therefore do not necessarily require external lenses in miniaturized systems [12]. Alternatively, single mode emission can be achieved without gratings utilizing coupled ridge cavities [13], a coupled active ring resonator [14] or Mach–Zehnder interferometer type cavities [15]. Without the need of high quality lithography, their processing is the same as for a simple ridge laser.…”

Design of quantum cascade microcavity lasers based on Q factor versus etching depth

“…QC microcylinder lasers at a wavelength of 5 m were realized by the wet etching technique with circular and stadiumlike cross sections and an etching depth of 5.4 m [3], and QC microcylinder and quadrupolar-shaped microlasers at a wavelength 10 m were fabricated by the reactive ion etching technique with an etching depth of 9 -10 m [4,5]. Furthermore, QC spiral-shaped chaotic resonator lasers at a wavelength of 8 m [6] and QC ridge waveguide lasers coupled to an active ring resonator filter at a wavelength of 9 m [7] were fabricated by the inductively coupled plasma reactive ion etching technique with an etching depth of 15 and 16 m, respectively. The reported etching depths vary from the magnitude of the emitting wavelength to about twice the wavelength.…”

“…Recently, finite-difference time-domain (FDTD) techniques were applied to investigate the mode characteristics [8,9], to optimize device structures [7], and to estimate radiative loss for QC microcavity lasers [10]. In this paper, the mode characteristics of microcylinders and mi-crosquares with mode wavelengths of about 4.8 and 7.8 m are investigated by the three-dimensional (3D) FDTD technique.…”