High-efficiency mid-infrared InGaAs/InP arrayed waveguide gratings

Abstract

Photonic integrated circuits and mid-infrared quantum cascade lasers have attracted significant attention over the years because of the numerous applications enabled by these compact semiconductor chips. In this paper, we demonstrate low loss passive waveguides and highly efficient arrayed waveguide gratings that can be used, for example, to beam combine infrared (IR) laser arrays. The waveguide structure used consists of an In0.53Ga0.47As core and InP cladding layers. This material system was chosen because of its compatibility with future monolithic integration with quantum cascade lasers. Different photonic circuits were fabricated using standard semiconductor processes, and experiments conducted with these chips demonstrated low-loss waveguides with an estimated propagation loss of ∼ 1.2 dB/cm as well as micro-ring resonators with an intrinsic Q-factor of 174,000. Arrayed waveguide gratings operating in the 5.15–5.34 µm range feature low insertion loss and non-uniformity of ∼ 0.9 dB and ∼ 0.6 dB, respectively. The demonstration of the present photonic circuits paves the path toward monolithic fabrication of compact infrared light sources with advanced functionalities beneficial to many chemical sensing and high-power applications.

Mid-infrared InP photonic integrated circuits

“…Depending on the waveguide design, the total absorption loss can be smaller than those. There are two recent reports demonstrating the low propagation loss of 0.5 dB/cm at 5.35 µm [5] and 1.2 dB/cm near 5.2 µm [6] which confirms the low loss property of the InGaAs/InP platform.…”

Monolithic beam combined quantum cascade laser arrays with integrated arrayed waveguide gratings

“…In response to these challenges, a monolithic integration approach featuring an all III-V semiconductor design has emerged as a promising solution [4]. Building on our previous work with InGaAs/InP-based AWG, which exhibited insertion losses comparable to silicon counterparts [5], we extend our design strategy to fabricate AWG with multi-quantum wells as the core material. This innovative approach enables a seamless transition from the active QCL to the passive beam combining section, as illustrated in Figure 1.…”

Low-Loss Buried InGaAs/InP Integrated Waveguides in the Long-Wave Infrared

“…Among them, InGaAs and InAlAs waveguides with InP cladding are particularly promising, given the technological maturity of current semiconductor quantum cascade lasers (QCL) based on that set of materials. ,, For instance, InGaAs membrane waveguides have been reported in the literature, achieving 4.1 dB/cm propagation losses at a 6.1 μm wavelength . InGaAs/InP passive waveguides patterned by dry-etching have also been demonstrated, reporting ∼1.2 dB/cm propagation losses a near 5.2 μm wavelength and 2.9 dB/cm at a 7.4 μm wavelength . The use of proton implantation has also been reported as a method to reduce the free carriers of originally active waveguides of QCLs to make them passive, reporting losses of approximately 1.4 dB/cm at a 9.6 μm wavelength .…”