Interband Cascade Photonic Integrated Circuits on Native III-V Chip.

Jerry R Meyer,William W Bewley,Chadwick L Canedy,Mijin Kim,Chul Soo Kim,Charles D Merritt,Igor Vurgaftman

doi:10.3390/s21020599

Abstract

We describe how a midwave infrared photonic integrated circuit (PIC) that combines lasers, detectors, passive waveguides, and other optical elements may be constructed on the native GaSb substrate of an interband cascade laser (ICL) structure. The active and passive building blocks may be used, for example, to fabricate an on-chip chemical detection system with a passive sensing waveguide that evanescently couples to an ambient sample gas. A variety of highly compact architectures are described, some of which incorporate both the sensing waveguide and detector into a laser cavity defined by two high-reflectivity cleaved facets. We also describe an edge-emitting laser configuration that optimizes stability by minimizing parasitic feedback from external optical elements, and which can potentially operate with lower drive power than any mid-IR laser now available. While ICL-based PICs processed on GaSb serve to illustrate the various configurations, many of the proposed concepts apply equally to quantum-cascade-laser (QCL)-based PICs processed on InP, and PICs that integrate III-V lasers and detectors on silicon. With mature processing, it should become possible to mass-produce hundreds of individual PICs on the same chip which, when singulated, will realize chemical sensing by an extremely compact and inexpensive package.

Highlights

Recent years have seen an accelerating development of optical technologies operating in the midwave infrared
Note that the photonic integrated circuit (PIC) can spectroscopically probe a narrow analyte fingerprint absorption line in multiple ways. These include tuning the wavelength of a single-mode laser source, tuning the resonance of a resonator sensing waveguide, such as a ring, tuning the wavelength of an inplane resonant cavity detector, separating the spectral components of a broadband signal, integrating multiple sensors operating at different absorption and reference wavelengths on the same chip, or dual-comb spectroscopy with multi-heterodyne detection
The preceding sections have presented a framework for constructing interband cascade laser (ICL)-based PICs on the native GaSb substrate

Summary

Introduction

Recent years have seen an accelerating development of optical technologies operating in the midwave infrared (mid-IR). While other sensing techniques, such as gas chromatography and monitoring variations in the properties of metal oxide semiconductors or polymers, may be employed [6], laser spectroscopy combines the advantages of selectivity, sensitivity, stability, longevity, and range in the case of remote sensing [5] It follows that rather than using bulky and costly discrete optical elements interacting across free space, the ideal spectroscopic sensing system will occupy a single semiconductor chip that is inexpensive to produce in mass quantities [5]. The University of California Santa Barbara (UCSB), NRL, and University of Wisconsin recently reported the first successful integration of mid-IR QCLs on silicon [22,23] Those PICs were formed by heterogeneously bonding active III-V wafer materials to a silicon-nitride-on-insulator (SONOI) chip that was pre-patterned with passive waveguides and DFB gratings. An alternative approach to the integration of mid-IR sources on silicon has been to grow InP-based QCLs directly onto silicon substrates [25,26]

Building Blocks

Schematic cross processed from thethe epitaxial structure of Figure

Schematic

Integrated ICL with Enhanced Stability

Integration

Conclusions