Proceedings Article | 14 March 2013
KEYWORDS: Silicon, Waveguides, Germanium, Photonics, Sensors, Semiconductor lasers, Spectrometers, Photonic integrated circuits, Plasmonics, Nonlinear optics
This paper outlines the challenges and benefits of applying silicon-based photonic techniques in the 2 to 5 μm midinfrared
(MIR) wavelength range for chem.-bio-physical sensing, medical diagnostics, industrial process control,
environmental monitoring, secure communications, Ladar, active imaging, and high-speed communications at 2 μm. Onchip
passive and active components, mostly waveguided, will enable opto-electronic CMOS or BiCMOS integrated
“circuits” for system-on-a-chip applications such as spectroscopy and lab-on-a-chip. Volume manufacture in a silicon
foundry is expected to yield low-cost (or even disposable) chips with benefits in size-weight-power and ruggedness. This
is “long-wavelength optoelectronic integration on silicon” which we call LIOS. Room temperature operation appears
feasible, albeit with performance compromises at 4 to 5 μm. In addition to the electronics layer (which may include RF
wireless), a 3-D LIOS chip can include several inter-communicating layers utilizing the photonic, plasmonic, photoniccrystal
and opto-electro-mechanical technologies. The LIOS challenge can be met by (1) discovering new physics, (2)
employing “new” IV and III-V alloys, (3) scaling-up and modifying telecom components, and (4) applying nonlinearoptical
wavelength conversion in some cases. This paper presents proposals for MIR chip spectrometers employing
frequency-comb and Ge blackbody sources. Active heterostructures employing Si, Ge, SiGe, GeSn and SiGeSn are key
for laser diodes, photodetectors, LEDs, switches, amplifiers, and modulators that provide totally monolithic foundry
integration, while numerous III-V semiconductor MIR devices within the InGaAsSb and InGaAsP families offer
practical hybrid integration on Si PICs. Interband cascade and quantum cascade lasers on Ge waveguides are important
in this context.
