Low noise transimpedance amplifier design

The aim of this research is to study a simplified approach for the design of low-noise bipolar transimpedance preamplifiers for optical receivers. Analytical solutions for optimum biasing and minimum equivalent input-noise current were derived. The study was achieved by doing comparison between the designed circuits. The equivalent input noise current was calculated by entering the parameters in Matlab program and using Multisim as a simulation tool to detect a pulse signal of 30ns width.

Analysis of detection sensitivity in optical preamplifier

The aim of this research is to study of detection sensitivity in optical preamplifier, which is used as a first stage in optical receivers. This subject is important because it is used in laser rangefinders. The parameters that affect the distance measurement using time of flight technique are studied in details. Then, noise analysis and signal to noise ratio calculation are performed in preamplifiers to detect a signal with pulse width of 30ns using Matlab. The study results are applied to some preamplifiers to determine the minimum detectable power.

The Retroreflection Index of Optical and Opto-electronical Systems

The retroreflection phenomenon takes place in all optical and optoelectronical devices and systems that use optical detectors, mirrors, CCD cameras, filters, or glasses in the focal point and in the optical measurement instruments, in general, provided that some of their optical components are retroreflective to light even for small apertures. The article studies a precise method to measure the retroreflection index of optical, opto-electronical systems, and treats the optical retroreflections which are used in applied research of light with various lasers such as: Nd:YAG first and second harmonics, He-Ne, and laser diodes. We have studies the conformity of our results to the theory of retroreflectors. We found that the retroreflection coefficient depends on laser wavelength. The article points out that at 532nm laser wavelength the retroreflection is greater than at 1064nm laser wavelength. The results of this paper can be used in applied research, and led to description of a mathematical relationship between the retroreflection index and laser wavelength.

Synthesis and spectroscopic characterization of GGG nanocrystals, doped with neodymium and chromium for high power solid state lasers

Gadolinium gallium garnet Gd3Ga5O12 (GGG) co-doped with chromium and neodymium have attracted attention as an active material for high power solid state laser.