Low-Illumination Level Uni-Traveling Carrier Photodetectors for Quantum Information Science Applications (Final Technical Report)
- Phase Sensitive Innovations, Inc., Newark, DE (United States)
Photodetectors with enhanced Photon Detection Efficiency (PDE) are an enabling component for many applications of Quantum Information Science (QIS). In squeezed state systems such as the Laser Interferometer Gravitational-Wave Observatory (LIGO) for example, beating the noise performance of traditional shot noise limited photonic sensors is only possible using a photodetector with sufficient Quantum Efficiency (QE). While QIS is a rapidly growing field, it is still small, and thus there is still a distinct lack of such commercial photodetectors for supporting these novel quantum technologies within universities, national labs, and the private sector. As such, the Department of Energy (DOE) tasked Phase Sensitive Innovations, Inc. (PSI) to design, fabricate, and package a high-QE (>95%) photodetector with operational bandwidth greater than 5 GHz for QIS applications. To do this, PSI - leveraging the expertise of the University of Virginia - designed, fabricated, and characterized high-QE photodetector chips as the core components of this effort. To support future commercial packaging of these devices, PSI developed low-loss optical and Radio Frequency (RF) integration processes, and designed biasing circuitry. Finally, PSI designed, packaged, and characterized a proof-of-concept high-QE photodetector module. Ultimately, PSI successfully developed a InGaAs/InP Uni-Traveling Carrier (UTC)photodetector with measured QE of over 99% at an optical wavelength of 1550 nm. This is sufficient for the detection of squeezed states greater than 20 dB, which is a major research goal of the DOE that has not yet been demonstrated within a laboratory setting. Additionally, with the application of broadband anti-reflective coating, this high-QE may be optimized down to wavelengths approaching InP’s cutoff wavelength of 920 nm. The detector structure was optimized for the low illumination intensities often used in quantum systems, demonstrating a carrier transit time limited bandwidth of 12.5 GHz and low dark current. For future commercial offering of this photodetector, PSI developed a custom high-QE photodetector package capable of integrating this device with over 99% optical coupling efficiency. The InP substrate is thinned to less than 100 µm which allows a fiber to directly feed the photodetector without an intermediate lens assembly, which would introduce excess loss. Within the package the photodetector chip is flip-chip bonded to an Aluminum Nitride (AlN) submount with a folded co-planar waveguide. This novel package geometry supports in-line optical and RF connectors without the introduction of optical loss from a right-angle prism or optical waveguide feed. Lastly, PSI integrated a low loss bias tee design into the module that features a low cutoff frequency compatible with the <12.5 GHz response of the new photodetector. The novel combination of near unity QE and high-speed response makes this proposed detector module ideal for QIS applications such as entanglement measurements, quantum sensors, and receivers for quantum links and networking, for which there is currently a lack of commercial support. Under a Phase II effort, PSI would (1) transition this new package into a commercial offering available for use at optical wavelengths 1064-1550 nm, and (2) develop specifications for the package at the cryogenic temperatures needed for significant reductions in thermal noise.
- Research Organization:
- Phase Sensitive Innovations, Inc., Newark, DE (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- SC0019858
- OSTI ID:
- 1787958
- Type / Phase:
- SBIR (Phase I)
- Report Number(s):
- DOE-PSI-SC19858
- Country of Publication:
- United States
- Language:
- English
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