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Papers by Michael Krainak

2006 Digest of the LEOS Summer Topical Meetings, Sep 22, 2006

InGaAs APDs with improved photon counting characteristics were designed and fabricated and their ... more InGaAs APDs with improved photon counting characteristics were designed and fabricated and their performance improvements were observed. Following the results, a 4times4 individually addressable APD array was designed, fabricated, and results are reported

$Research paper thumbnail of Photorefractive charge migration in BSO: A comparison of the band transport and hopping models$

There is a continued interest in the charge transport mechanism for the photorefractive effect, p... more There is a continued interest in the charge transport mechanism for the photorefractive effect, particularly in the sillenites (BSO, BGO, BTO)1,2. There are two prevalent models for the photoexcited charge migration, namely, the band transport theory and the hopping model3. In this paper we present a detailed comparison of the hopping and band transport models. We place the hopping model in the same framework as the band transport model. The hopping model is then modified to include an external electric field dependent time constant. This allows the development of an expression for the total electric space charge field for the condidtion of an externally applied alternating electric field. This expression is used in the electromagnetic coupled wave theory to predict the two wave mixing gain. Experimental and theoretical results are then compared. AC photoconductivity experimental results and theoretical predictions are also presented and compared.

Proceedings of SPIE, May 5, 2016

Proceedings of SPIE, Aug 16, 1994

There is a growing interest in applying the resources of the Tracking and Data Relay Satellite Sy... more There is a growing interest in applying the resources of the Tracking and Data Relay Satellite System (TDRSS) as the primary support capability for future small satellite users. This interest is based on a variety of benefits offered by the TDRSS, and not available with globally-distributed space-ground links. An architecture based on an optical augmentation to the current TDRSS space network is discussed, including a candidate design for the user and relay terminals.

Proceedings of SPIE, Sep 24, 1986

A variety of acoustooptic signal processing architectures capable of producing triple products in... more A variety of acoustooptic signal processing architectures capable of producing triple products in real time are reviewed. As well a status report on the construction of a high bandwidth interferometric triple product processor is given.

Proceedings of SPIE, Sep 15, 1993

Proceedings of SPIE, May 4, 2007

ABSTRACT We report the test results of a hybrid photomultiplier tube (HPMT) with a transfer elect... more ABSTRACT We report the test results of a hybrid photomultiplier tube (HPMT) with a transfer electron (TE) InGaAsP photocathode and GaAs Schottky avalanche photodiode (APD) anode. Unlike Geiger mode InGaAsP APDs, these HPMTs (also known as intensified photodiode (IPD), vacuum APD, or hybrid photodetector) operate in linear mode without the need for quenching and gating. Their greatest advantages are wide dynamic range, high speed, large photosensitive area, and potential for photon counting and analog detection dual mode operation. The photon detection efficiency we measured was 25% at 1064 nm wavelength with a dark count rate of 60,000/s at -22 degrees Celsius. The output pulse width in response to a single photon detection is about 0.9 ns. The maximum count rate was 90 Mcts/s and was limited solely by the speed of the discriminator used in the measurement (10 ns dead time). The spectral response of these devices extended from 900 to 1300 nm. We also measured the HPMT response to 60 ps laser pulses. The average output pulse amplitude increased monotonically with the input pulse energy, which suggested that we can resolve photon number in an incident pulse. The jitter of the HPMT output was found to be about 0.5 ns standard deviation and depended on bias voltage applied to the TE photocathode. To our knowledge, these HPMTs are the most sensitive non gating photon detectors at 1064 nm wavelength, and they will have many applications in laser altimeters, atmospheric lidars, and free space laser communication systems.

$Research paper thumbnail of Coherent optical detection through two-wave mixing in photorefractive materials$

Optics Letters, Jun 1, 1988

Photorefractively induced index-of-refraction phase gratings are shown to combine coherently the ... more Photorefractively induced index-of-refraction phase gratings are shown to combine coherently the optical fields of a strong pump and a suitably amplitude- or phase-modulated signal beam in such a way that an apparent amplification of the modulating waveform appears as intensity modulation of the transmitted signal and pump beam intensities. The source of the signal gain is shown to be the square-law (intensity) detection of the coherently combined pump and modulated signal beams, just as in coherent optical communication systems in which a strong local-oscillator field is coherently added with a weak optical signal field by a beam splitter.

Image amplification using photorefractive two-wave mixing is attractive since high gain and high ... more Image amplification using photorefractive two-wave mixing is attractive since high gain and high signal-to-noise ratios are achievable using relatively low-power lasers. Huignard et. al. have achieved high gains in Bi12SiO20 (BSO) using the DC field and moving grating technique1. The disadvantages of this technique are the uniform illumination and external frequency shift requirements. Another option is the use of alternating electric fields as suggested by Stepanov and Petrov2. This technique has been demonstrated in BTO2 and GaAs3. It maintains the 90o phase shift between the incident fringe pattern and holographic grating required for image amplification, while allowing enhancement of the refractive index change via the external field. Other advantages include increased stability, no requirement for uniform illumination, and the avoidance of the electrode "shadowing" problem. In addition, the trap saturation regime (i. e. the maximum possible grating amplitude for a given material) can be reached at very high fields. The application of this technique to BSO has been suggested previously2,3,4, and preliminary results are presented here.

arXiv (Cornell University), Aug 3, 2022

Journal of physics, May 1, 2017

2023 IEEE Aerospace Conference

Holography

We present experimental evidence of electron compensation of a fixed ionic hologram in a photoref... more We present experimental evidence of electron compensation of a fixed ionic hologram in a photorefractive iron doped lithium niobate crystal configured as an optical filter.

CLEO Pacific Rim Conference, 2018

NASA GSFC is developing a space-based sodium resonance fluorescence lidar for the International S... more NASA GSFC is developing a space-based sodium resonance fluorescence lidar for the International Space Station (ISS). We discuss the technology, prototypes, risks and trades for two laser architectures - Raman laser and sum frequency generation.

Frontiers in Optics + Laser Science APS/DLS, 2019

Solid State Lasers XXVII: Technology and Devices, 2018

The high average power from pulsed good quality mode laser emitting at fundamental wavelength of ... more The high average power from pulsed good quality mode laser emitting at fundamental wavelength of 1066.3 nm is needed for obtaining of high-fidelity pulsed radiation with wavelength centered at 589.15 nm for spaceborne Na Doppler resonance fluorescence LIDAR. The conversion of radiation from 1066.3 nm to 589.15 nm can be achieved through one stage of Raman lasing and subsequent frequency doubling using qualified nonlinear crystals. Although efficient scaling of average power at 1064 nm using a-cut Nd:YVO4 to multiple of 10W was demonstrated for more than a decade ago, the efficient demonstration of 1066 nm power scaling from single Watt level to 10W level of average power is yet to be done. Multiple publications with a-cut Nd:YVO4 laser host with fundamental emission wavelength at 1064 nm showed good conversion efficiencies to both 1176 nm and to 588 nm using intracavity Raman lasing and frequency doubling. We experimentally demonstrated efficient lasing at 1066 nm with output average power in excess of 15W using single c-cut Nd:YV04 crystal end-pumped with 888 nm diode pump laser. The achieved optical-to-optical efficiency of converting absorbed 888 nm pump to 1066 nm with short linear test cavity and output coupler of 84% was in excess of 32% while maximum reached optical-to-optical slope efficiency 50%. We discuss challenges of efficient 1066 nm generation and overall electro-optical efficiencies reachable for potential spaceborne LIDAR Sodium transmitter laser.