The short-wave infrared wavelength range (2-3 μm) is attractive for applications in gas sensing and next-generation communication systems. Photodetectors and wavelength (de)multiplexers are key components that have to be developed for these systems. In this contribution, we report the integration of InGaAs/GaAsSb type-II quantum well photodetectors and spectrometers on the silicon photonics platform. In this photodetector epitaxial layer stack, the absorbing active region consists of 6 periods of W-shaped quantum wells, which can also be used to realize lasers. The efficient coupling between silicon waveguides and quantum well photodetectors is realized by tapered III-V waveguides. The photodetectors have a very low dark current of 12 nA at -0.5 V bias at room temperature. The devices show a responsivity of 1.2 A/W at 2.32 μm wavelength, and higher than 0.5A/W over the 2.2-2.4 μm wavelength range. On the silicon-on-insulator platform we also demonstrate high performance short-wave infrared spectrometers. 8-channel spectrometers in the 2.3-2.4 μm range with a resolution of 5nm and 1.4nm are demonstrated, showing a cross-talk below -25 dB and an insertion loss lower than 3 dB.
Type-II light sources on InP substrate are an innovative concept for wavelengths ranging from 2 μm to the mid-IR. The concept is using the type-II band alignment between GaInAs and GaAsSb to exceed the limitation of type-I devices. Since the first demonstration of InP type-II heterostructure lasers above 2.3 μm in 2012, we have extended the emission wavelength to 2.7 μm. Furthermore, a drastic reduction in threshold current density down to 104 A/cm2 per QW at infinite length was achieved (at 2.5 μm), which represents an improvement by more than a factor of two. Additionally CW operation up to 30°C and up to 80°C pulsed is presented. Furthermore, LEDs for 3.5μm peak emission wavelength and up to 86 μW output power are shown.
We present different concepts for long wavelength buried tunnel junction VCSELs for the spectroscopically important range above 2 μm. This includes GaSb-based laser using GaInAsSb quantum wells, InP-based lasers with V-shaped quantum wells and InP-based lasers using type-II quantum wells. For InP-based devices, emission wavelengths up to 2.36 μm are presented, with single-mode output powers of roughly 500 μW and side-mode suppression ratios of more than 30 dB. GaSb-based VCSELs are presented with single-mode emission at 2.6 μm, a side-mode suppression ratio of more than 20 dB and a peak output power of 400 μW.
GaSb-based type-I quantum-well lasers, emitting in the spectral range from 2 to 4 μm are promising light sources for
various trace gas sensing systems by means of tunable diode laser absorption spectroscopy (TDLAS). Excellent device
performance has been achieved so far in the spectral range from 2 to 3 μm, however, room-temperature operation above
3 μm is much more difficult to achieve. In this work we demonstrate the extension of room-temperature operation
wavelength of GaSb-based type-I lasers up to 3.73 μm by implementation of high-quality quinternary AlGaInAsSb