Pendar Technologies (United States)

Mid-infrared photonics is a widely researched field with several applications, such as chemical sensing and spectroscopy. The development of photonic integrated circuits for the mid-infrared can enable the reduction in device size, weight, and power (SWaP) consumption. This paper demonstrates arrayed waveguide gratings working in the mid-infrared regime (5–5.4 µm). Our devices are fabricated on an InP-based quantum cascade laser platform with the gain medium as the waveguide core. To minimize the propagation losses caused by free carrier absorption and intersubband absorption in the unbiased QCL structure, we exposed the photonic chips to proton implantation. The performance of three sets of AWGs with different etch depths was characterized. The lowest waveguide losses were measured to be 2 dB/cm. The best performing 7×1 AWG and 13×1 AWG designs featured insertion losses of −2dB and −2.5dB, respectively. This study showcases the feasibility of applying such a platform for easy integration with active components like lasers and photodetectors, paving the path for on-chip mid-infrared applications.

We report the fabrication of arrayed waveguide gratings on a quantum cascade laser (QCL) wafer. The waveguides employ a strained InGaAs/InAlAs gain medium as the core material grown on an InP substrate.

We report the fabrication of InGaAs/InP based arrayed waveguide gratings featuring low insertion loss and non-uniformity. This device can be integrated monolithically with on-chip III-V lasers to make compact high-power mid-infrared sources.

We present a QCL-based mid-IR dual-comb spectrometer that can be automatically reconfigured between two sensing modalities: an extractive point sensing and a remote retroreflector-based sensing. A proof-of-concept field demonstration presents its adaptability to different sensing scenarios.

This presentation introduces the spectroscopic concepts and results enabled by arrays of Distributed Feedback (DFB) QCLs, with each element at a slightly different wavelength than its neighbor. In portable optical systems, such as standoff threat detectors and in situ gas analyzers, this increases analyte sensitivity and selectivity by broadening spectral source coverage while also allowing for extremely fast all-electronic wavelength tuning with no moving parts. This talk will first present the QCL array and its packaging, then move into the description of an integrated prototype standoff detection system, and finally show condensed phase standoff threat detection results from a handheld system from over 1 meter. These data are each compared with legacy contact-based methods to ensure that the technique can be reliably deployed to handheld chemical analysis using suitable chemometric algorithms. The data show how monolithic and all-electronic tuning enables next-generation spectroscopes that are not only more robust and miniature than those that utilize external cavity-tuned lasers, but that are inherently more stable in terms the shot-to-shot amplitude and wavelength parameters. This enhanced stability increases signal to noise for a given configuration (pathlength, averaging time, concentration, etc…). Some discussion of how to maximize the benefits of high speed, highly reproducible tuning is presented, including detector, preamplifier, and digitization considerations.

Abstract Most preparations for making neural recordings degrade over time and eventually fail due to insertion trauma and reactive tissue response. The magnitudes of these responses are thought to be related to the electrode size (specifically, the cross-sectional area) and the relative stiffness of the electrode material. Carbon fiber ultramicroelectrodes have a much smaller cross-section than traditional electrodes and thus may enable improved longevity of neural recordings in the central and peripheral nervous systems. Only two carbon fiber array designs have been described previously, each with limited channel densities due to limitations of the fabrication processes or interconnect strategies. Here, we describe a method for assembling carbon fiber electrodes on a flexible polyimide substrate that will facilitate the construction of high-density recording and stimulating arrays for acute use in peripheral nerves. Fibers were aligned using an alignment tool that was 3D-printed with sub-micron resolution using direct laser writing. Indium deposition on the carbon fibers provided a robust and reliable method of electrical connection to the polyimide traces. Spontaneous action potentials and stimulation-evoked compound responses with SNR > 10 and > 120, respectively, were recorded from a small (125 μm) peripheral nerve. We also improved the typically poor charge injection capacity of small diameter carbon fibers can be improved by electrodepositing 100 nm thick iridium oxide films, making the carbon fiber arrays suitable for electrical stimulation as well as recording.