Strong coupling of metamaterial resonances to intersubband transitions of quantum dots for enhanced second-harmonic generation.

Recently, quantum confined structures have been widely studied for their nonlinear properties and applications in harmonic generation. However, because of lower orders of susceptibility, the generated harmonic power is low. In this paper, we present coupling of metamaterial resonance to intersubband transitions of quantum dots (QDs) for enhanced second-harmonic generation efficiency.

Analysis of single photon detection in avalanche photodetectors with multi-gain-stage multiplication region.

We report the design and analysis of a single photon avalanche detector (SPAD) with cascaded multiplication stages with asymmetric gain series for near-IR applications. The asymmetric gain profile allows us to selectively enhance the ionization coefficient for injected electrons and suppress the hole-initiated ionization by repetition of high and low field layers. The low field layer acts as a carrier relaxation region, which inhibits avalanche feedback between stages; hence, it is expected to have a lower dark count rate (DCR).

Design of resonant cavity structure for efficient high-temperature operation of single-photon avalanche photodiodes.

A novel design of a single-photon avalanche photodiode (SPAD) is proposed based on resonant cavity (RC) structure, and its performance is studied. In the proposed structure, InAlAs/InGaAs distributed Bragg reflectors (DBRs) are employed as top and bottom mirrors and the quantum efficiency (QE) of the absorption region is calculated considering the effect of the RC. Results show that using 12 periods of DBRs as a bottom reflector without incorporation of a top mirror can enhance the QE to about 90% at room temperature.

Quantum dot infrared photodetector with gated-mode design for mid-IR single photon detection.

A novel design for a quantum dot infrared photodetector (QDIP) is proposed based on avalanche multiplication and is expected to be used as a single photon detector at mid-IR. A high field multiplication region is added to a conventional QDIP in separate absorption, charge, and multiplication structures to intensify incoming photocurrent generated in the absorption region. The absorption region of the photodetector consists of quantum dot layers that are responsible for absorption of mid-IR wavelengths.