Robert G. W. Brown

Characterization of silicon avalanche photodiodes for photon correlation measurements. 1: Passive quenching

We examine the photon correlation and other vital performance characteristics of silicon avalanche photodiodes operated in photon counting or the Geiger mode, and assess their suitability as detectors for photon correlation spectroscopy and laser velocimetry measurements.

Dynamic light scattering using monomode optical fibers

We describe the use of monomode optical fibers in dynamic light scattering, i.e., photon correlation spectroscopy or quasi-elastic light scattering.

Miniature laser light scattering instrumentation for particle size analysis

We describe the design, construction, and testing of a miniature, all-solid state laser light scattering instrument for determination of particle sizes and distributions using photon correlation spectroscopy techniques (i.e., quasielastic or dynamic light scattering). Detailed comparative tests with standard photon correlation spectroscopy equipment are presented.

Optical characteristics of III-nitride quantum wells with different crystallographic orientations

This article presents a direct comparison of calculated optical characteristics of polar, nonpolar, and semipolar III-nitride quantum wells. We show that the advantage of using wider quantum wells offered by nonpolar/semipolar technology is severely limited by narrower valence subband separation, thermal hole redistribution, and resulting optical gain degradation in wider wells. However, we emphasize the importance of using wider quantum wells to prevent electron leakage. We also show that gain characteristics of laser structures grown in nonpolar/semipolar orientations are less vulnerable to detrimental effect of nonradiative recombination.

Photon statistical properties of visible laser diodes

We investigate the factorial moments and photon correlation properties of two Sharp Corporation 780‐nm laser diodes and assess their suitability for use in photon counting and correlation experiments.

Versatile high temperature flow reactor for kinetic and spectroscopic studies

A high temperature flow reactor has been constructed to perform kinetic and spectroscopic studies on species at temperatures between 300 and 1500 K. The species in the flow reactor may be detected or studied using: laser‐induced fluorescence, resonance fluorescence, infrared absorption, ultraviolet absorption, chemiluminescence, or molecular beam mass spectrometry. The features of the apparatus are described in detail, and the initial spectroscopic and kinetic studies are discussed.

Optimum quantum well width for III-nitride nonpolar and semipolar laser diodes

The advantage of using wider quantum wells in III-nitride lasers offered by nonpolar/semipolar technology is limited by narrower valence subband separation, thermal hole redistribution, and resulting optical gain degradation in wider wells. We show that corresponding increase in radiative carrier lifetime in wider quantum wells can lower the laser threshold, thus inferring the existence of an optimum quantum well width for laser design.

Homodyne optical fiber dynamic light scattering.

Optical fiber homodyne dynamic light scattering employs both the advantage of a sensitivity improvement over the standard self-beating technique and the inherent self-aligning simplicity of the optics. Ultralow concentrations of approximately nanometer-sized particles become accessible by dynamic light-scattering techniques.

Characterization of silicon avalanche photodiodes for photon correlation measurements. 3: Sub-Geiger operation

We continue examination of the photon correlation properties of silicon avalanche photodiodes operated in the single-photon counting mode by extending their operation from that of passive [Appl. Opt. 25, 4122-4126 (1986)] and active [Appl. Opt. 26, 2383-2389 (1987)] quenching to the sub-Geiger mode, with potential for high quantum efficiency and very low afterpulsing.

Determination of protein size in chromatography column eluants by on-line photon correlation spectroscopy

The dynamic light scattering technique of photon correlation spectroscopy has been used to determine biomacromolecule hydrodynamic radius in solutions flowing at rates similar to those experienced in liquid chromatographic separation systems. Such analyses can be performed rapidly (less than 5 s). The potential of the technique as an on-line noninvasive monitor for liquid chromatography is discussed.