Spectral region beyond 1.7 μm is particularly interesting for biomedical spectroscopic sensing applications due to the presence of strong and molecule-specific ro-vibrational overtone and combination absorption bands for a number of important analytes such as glucose, lactate, urea, human serum albumin among others. However, this spectral region has been largely unexplored for applications targeting wearable device technology due to the absence of commercially available semiconductor light source technology. In this work we report on recent progress in developing beyond-stateof-the-art GaSb-based swept-wavelength laser technology as a key building-block of the proposed spectroscopic sensor concept. To demonstrate the capability of the technology, we provide experimental data of in vitro sensing concentrations down to the normal physiological range and beyond for glucose, lactates, urea and bovine serum albumin. Furthermore, we provide initial experimental evidence of non-invasive in vivo sensing experiment with extracted absorbance signature of human serum albumin collected from the wrist and demonstrate a clear path towards sensing other analytes. Finally, to demonstrate the full potential of the spectroscopic sensor technology for the wearable device market, we present results of our initial effort to realize a complete spectroscopic sensor system-on-a-chip based on hybrid GaSb/Si material platform and manufactured using conventional 200 mm silicon-on-insulator CMOS technology process in a commercial high-volume foundry.
III-V/silicon photonic integrated circuits (ICs) promise to enable low cost and miniature optical sensors for trace-gas detection, bio-sensing and environmental monitoring. A lot of these applications can benefit from the availability of photonic ICs beyond the telecommunication wavelength range. The 2 μm wavelength range is of interest for spectroscopic detection of many important gases and blood constituents. In this contribution we will present 2 μmwavelength-range III-V/silicon photonic ICs consisting of tunable laser sources, photodetectors and silicon waveguide circuits. Silicon waveguides with a loss of ~0.5 dB/cm are obtained in a well-established silicon photonics platform. Based on the waveguides, low insertion loss (2-3 dB) and low crosstalk (25-30 dB) arrayed waveguide gratings (AWGs) are realized for the 2.3 μm wavelength range. Active opto-electronic components are integrated on the photonic IC by the heterogeneous integration of an InP-based type-II epitaxial layer stack on silicon. III-V-on-silicon 2.3 μm range distributed feedback (DFB) lasers can operate up to 25 °C in continuous-wave regime and shows an output power of 3 mW. By varying the silicon grating pitch, a DFB laser array with broad wavelength coverage from 2.28 μm to 2.43 μm is achieved. III-V-on-silicon photodetectors with the same epitaxial layer stack exhibit a responsivity of 1.6 A/W near 2.35 μm. In addition, we also report a 2 μm range GaSb/silicon hybrid external cavity laser using a silicon photonic IC for wavelength selective feedback. A wavelength tuning over 58 nm and side mode suppression ratio better than 60 dB is demonstrated.
In this work we present latest achievements on gain chips as sources for single-frequency tunable laser absorption spectroscopy and sensing. External cavity lasers based on Brolis Semiconductors (2.05 – 2.45) μm wavelengths GaSb gain chips exhibited single mode laser emission with linewidths <100 kHz and output powers of <5 mW in the entire tuning range of <100 nm per chip. Continuous current tuning of 60 GHz and mode-hop free piezo tuning of 26 GHz were demonstrated. Additionally, we report on extended wavelengths range by demonstrating low spectral modulation 850 nm GaAs-based gain chips. Finally, experimental results on GaSb-based gain chip integration with silicon photonics are presented.
In this work we present latest results on mid-infrared GaSb gain chips as high-output power narrow-linewidth continuouswave single-frequency laser sources for ultra-widely tunable spectroscopy and sensing applications. More than 30 mW CW output power with over 100 nm / chip tuning and < 1 MHz linewidth performance is demonstrated in the entire band from 1900 nm – 2450 nm covering most essential absorption features from CO, CO2, NH3, CH4 and N2O for environmental and medical applications. Finally, we report on complete single-frequency laser system with integrated gain-chip for highresolution spectroscopy and sensor applications.
Mid-infrared spectral region (2-4 μm) is gaining significant attention recently due to the presence of
numerous enabling applications in the field of gas sensing, medical, and defense applications. Gas sensing in this spectral
region is attractive due to the presence of numerous absorption lines for such gases as methane, ethane, ozone, carbon
dioxide, carbon monoxide, etc. Sensing of the mentioned gas species is of particular importance for applications such as
atmospheric LIDAR, petrochemical industry, greenhouse gas monitoring, etc. Defense applications benefit from the
presence of covert atmospheric transmission window in the 2.1-2.3 micron band which is more eye-safe and offers less
Rayleigh scattering than the conventional atmospheric windows in the near-infrared. Major requirement to enable these
application is the availability of high-performance, continuous-wave laser sources in this window. Type-I GaSb-based
laser diodes are ideal candidates for these applications as they offer direct emission possibility, high-gain and continuous
wave operation. Moreover, due to the nature of type-I transition, these devices have a characteristic low operation
voltage, which results in very low input powers and high wall-plug efficiency.
In this work, we present recent results of 2 μm – 3.0 μm wavelength room-temperature CW light sources based
on type-I GaSb developed at Brolis Semiconductors. We discuss performance of defense oriented high-power multimode
laser diodes with < 1 W CW power output with over 30 % WPE as well as ~ 100 mW single TE00 Fabry-Perot chips. In
addition, recent development efforts on sensing oriented broad gain superluminescent gain chips will be presented.
Mid-infrared spectral region (2-4 μm) is gaining significant attention recently due to the presence of numerous enabling applications in the field of gas sensing, medical, environmental and defense applications. Major requirement for these applications is the availability of laser sources in the atmospheric transmission window free of water vapor absorption, such as the 2-2.3 μm spectral window. Type-I GaSb-based laser diodes are ideal candidates for these applications being compact, electrically pumped, power efficient and able to operate at room temperature in continuous-wave. Moreover, due to the nature of type-I transition these devices have characteristic low operation voltage, typically below 1 V, resulting in low power consumption, and high-temperature of operation. In this work, we present recent progress of 2.1 μm wavelength single-spatial mode GaSb type-I laser diode development at Brolis Semiconductors. Experimental device structures were grown by solid-source multi-wafer MBE, consisting of an active region with 2 compressively strained (~1.3 %) GaInAsSb quantum wells. Epi-wafers were processed into a ridge-waveguide devices and mounted on Cu or CuW heatsink. Presented devices feature state-of-the art performance in CW mode with < 1.2 W and 30 % WPE for single emitter device as well as 9 W and 28 % WPE for a laser diode bar.
Mid-infrared spectral region (2-4 μm) is gaining significant attention recently due to the presence of numerous enabling applications in the field of gas sensing, medical, environmental and defense applications. Major requirement for these applications is the availability of laser sources in this spectral window. Type-I GaSb-based laser diodes are ideal candidates for these applications being compact, electrically pumped, power efficient and able to operate at room temperature in continuous-wave. Moreover, due to the nature of type-I transition; these devices have a characteristic low operation voltage, typically below 1 V, resulting in low power consumption, and high-temperature of operation. In this work, we present recent progress of 2.7 μm – 3.0 μm wavelength single-spatial mode GaSb type-I laser diode development at Brolis Semiconductors. Experimental device structures were grown by solid-source multi-wafer MBE, consisting of an active region with 2 compressively strained (~1.3 %-1.5 %) GaInAsSb quantum wells with GaSb barriers for 2.7 μm devices and quinternary AlGaInAsSb barriers for 3.0 μm devices. Epi-wafers were processed into a narrow-ridge (2-4 μm) devices and mounted p-side up on CuW heatsink. Devices exhibited very low CW threshold powers of < 100 mW, and single spatial mode (TE00) operation with room-temperature output powers up to 40 mW in CW mode. Operating voltage was as low as 1.2 V at 1.2 A. As-cleaved devices worked CW up to 50 deg C.
Mid-infrared spectral region (2-4 μm) is gaining significant attention recently due to the presence of
numerous enabling applications in the field of gas sensing, medical, environmental and defense applications. Major
requirement for these applications is the availability of laser sources in this spectral window. Type-I GaSb-based laser
diodes are ideal candidates for these applications being compact, electrically pumped, power efficient and able to operate
at room temperature in continuous-wave. Moreover, due to the nature of type-I transition these devices have
characteristic low operation voltage, typically below 1 V, resulting in low power consumption, and high-temperature of
operation.
In this work, we present recent progress of 2.1 μm wavelength single-spatial mode GaSb type-I laser diode
development at Brolis Semiconductors. Experimental device structures were grown by solid-source multi-wafer MBE,
consisting of an active region with 2 compressively strained (~1.3 %) GaInAsSb quantum wells. Epi-wafers were
processed into a narrow-ridge (3-5 μm) devices and mounted p-side up on CuW heatsink. Devices exhibited very low
CW threshold powers of < 30 mW, and single spatial mode (TE00) operation with room-temperature output powers up
to 200 mW in CW mode with a far-field fast axis divergence angle of ~ 57 degrees.
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