In this work, we have proposed a model for the ultimate physical limit on the sensitivity of the heterojunction bipolar phototransistors (HPTs). Based on our modeling we have extracted the design criteria for the HPT for high sensitivity application. HPT with the submicron emitter and base area has the potential to be used for the low number photon resolving in near-infrared (NIR) wavelength. However, in practice, the quality of materials, processing, and the passivation plays an important role in the realization of the highly sensitive HPT. For short wave infrared (SWIR) HPTs based on lattice matched InGaAs to InP is studied. For these devices, conditions to reach to the highest possible sensitivity is examined. We have made an HPT based on InGaAs collector and base on the InP substrate. After developing proper processing combination of wet and dry etching and the surface passivation for the device we made an imager with 320x256 pixels based with a 30m pixel pitch. The imager shows the sensitivity less the 30 photons for each pixel with the frame rate more than 1K frames per second.
used for monitoring and profiling structures, range, velocity, vibration, and air turbulence. Remote sensing in the IR region has several advantages over the visible region, including higher transmitter energy while maintaining eye-safety requirements. Electron-injection detectors are a new class of detectors with high internal avalanche-free amplification together with an excess-noise-factor of unity. They have a cutoff wavelength of 1700 nm. Furthermore, they have an extremely low jitter. The detector operates in linear-mode and requires only bias voltage of a few volts. This together with the feedback stabilized gain mechanism, makes formation of large-format high pixel density electron-injection FPAs less challenging compared to other detector technologies such as avalanche photodetectors. These characteristics make electron-injection detectors an ideal choice for flash LiDAR application with mm scale resolution at longer ranges. Based on our experimentally measured device characteristics, a detailed theoretical LiDAR model was developed. In this model we compare the performance of the electron-injection detector with commercially available linear-mode InGaAs APD from (Hamamatsu G8931-20) as well as a p-i-n diode (Hamamatsu 11193 p-i-n). Flash LiDAR images obtained by our model, show the electron-injection detector array (of 100 x 100 element) achieves better resolution with higher signal-to-noise compared with both the InGaAs APD and the p-i-n array (of 100 x 100 element).
This article reports the progress on the development of a novel detector with the promise of addressing the needs of extreme AO (ExAO) in the near-IR band (NIR), 0.9-1.7 μm. The camera is based on the electron injection mechanism which resembles how the human eye processes light. The camera design allows high sensitivity operation at TEC reachable temperatures for ExAO at 1-4 kHz frame rates, and at the same time the concept produces sufficient gain to overcome the read noise of the device. Here we present the overall design, test results on Gen-1 (outdated but operable) camera, along with early results of our next generation of detectors.
Excitons, bound electron-hole pairs, possess distinct physical properties from free electrons and holes that can
be employed to improve the performance of optoelectronic devices. In particular, the signatures of excitons are
enhanced optical absorption and radiative emission. These characteristics could be of major benefit for the laser
cooling of semiconductors, a process which has stringent requirements on the parasitic absorption of incident
radiation and the internal quantum efficiency. Here we experimentally demonstrate the dominant ultrafast excitonic
super-radiance of our quantum well structure from 78 K up to room temperature. The experimental results are
followed by our detailed discussions about the advantages and limitations of this method.
The nanoplasmonic properties of apertures in metal films have been studied extensively; however, we have recently
discovered surprising new features of this simple system with applications to super-focusing and super-scattering.
Furthermore, apertures allow for optical tweezers that can hold onto particles of the order of 1 nm; I will briefly
highlight our work using these apertures to study protein - small molecule interactions and protein - DNA binding.
In this paper we describe the double nanohole laser tweezer system used to trap single nanoparticles. We cover the basic theory behind the DNH and what makes it more powerful than traditional laser tweezers commonly used for larger particles. We outline the basic setup used to reliably trap several different types of particles ranging in size from 1 nm to 40 nm. Data from several experiments is shown which displays exactly how a particle is confirmed to be trapped. We will discuss the use of autocorrelation as well as other information that can be extracted from the optical transmission in our setup and how it has been applied to the identification of protein small molecule interactions and protein binding. Other uses of the data collected from our setup will be discussed including the observation of protein folding. Finally we discuss the current developments of the process and its possible uses as a drug discovery tool, a new type of single particle nanopipette and new bio-sensors.