Monolithically integrated mid-infrared sensor using narrow mode operation and temperature feedback

Abstract

A method to improve the sensitivity and selectivity of a monolithically integrated mid-infrared sensor using a distributed feedback laser (DFB) is presented in this paper. The sensor is based on a quantum cascade laser/detector system built from the same epitaxial structure and with the same fabrication approach. The devices are connected via a dielectric-loaded surface plasmon polariton waveguide with a twofold function: it provides high light coupling efficiency and a strong interaction of the light with the environment (e.g., a surrounding fluid). The weakly coupled DFB quantum cascade laser emits narrow mode light with a FWHM of 2 cm−1 at 1586 cm−1. The room temperature laser threshold current density is 3 kA∕cm2 and a pulsed output power of around 200 mW was measured. With the superior laser noise performance, due to narrow mode emission and the compensation of thermal fluctuations, the lower limit of detection was expanded by one order of magnitude to the 10 ppm range.

Active Nanophotonic Circuitry Based on Dielectric‐loaded Plasmonic Waveguides

“…Concluding this section, we will just highlight the DLSPPW-related approaches in refractive index sensing for bio- [ 201,202 ] and chemical sensing, [ 203,204 ] for studies of quantum properties of plasmons [205][206][207] and their Anderson localization. [ 208 ] …”

Advances in Mid-Infrared Spectroscopy for Chemical Analysis

“…Complete integration of laser light source, waveguiding/sensing architecture, and detector has recently been elegantly shown by the Strasser group (81,82). A monolithic approach using quantum cascade-based source and detection structures along with a surface plasmon polariton www.annualreviews.org • Advances in MIR Spectroscopy for Chemical Analysis 55 Conjugated aptamers waveguide enabled the detection of water in ethanol via the absorption feature at 810 cm −1 with a dynamic range of 0-60% at parts-per-million detection levels (Figure 8).…”

“…Hence, recently emerging waveguide technologies focus on alternative MIR materials to facilitate the development and fabrication of planar single-mode MIR waveguide structures, enabling on-chip MIR photonics for label-free chem/bio and assay applications. Consequently, approaches using plasmonic structures (81,82), MCT (35), GaAs/AlGaAs, ZnSe, Ge (83,84), and diverse chalcogenide glasses (85) On-chip integration of waveguides offers the opportunity to use the same optical architecture for the waveguide and the active transducer element. As useful semiconductor materials usually have high refractive indices relative to the surrounding liquid or gas phase sample, sensing via the evanescent field is enabled.…”

Mid-infrared surface transmitting and detecting quantum cascade device for gas-sensing

“…Combining a QCLD material with plasmonics, an integrated sensor for fluidics has been shown with interaction regions in the range of tens of μm 23 . Recently, an improved signal to noise ratio multi-wavelength temperature stabilized sensor was demonstrated based on distributed feedback (DFB) lasers 24 . In this paper we extend the integration concept to gas sensing applications.…”