GaAs Detection Principle

The measurement principle is based on white light absorption/transmission by a GaAs (gallium arsenide) semiconductor. The impacts of temperature variations on this semiconductor are well known and predictable. As the temperature of the semiconductor changes, the semiconductor’s transmission spectrum (i.e. the light that is not absorbed) also shifts. At any given temperature, there will be a wavelength at which the transmission essentially jumps from 0% to 100%. This jump is called the absorption shift, and the relationship between the specific wavelength where the absorption shift takes place and the temperature is predictable.



The sensor consists of a tiny GaAs semiconductor crystal that is bonded to one end of a well-polished fiber optic.

Temperature Sensor

The white light launched from the monitor into the fiber optic travels through to the GaAs crystal, passing through it while being partially absorbed, and is then reflected to the monitor by a mirror located at the very tip of the sensor. The light reflected to the monitor is coupled into an optical spectrum analyzer, which then measures the optical power transmission versus the wavelength. The position of the absorption shift is determined by the monitor using a proprietary signal analysis algorithm and is then correlated to the temperature of the GaAs crystal.



Furthermore, since the semiconductor will not change over time, all sensors can be interchanged with no need for calibration or entry of factors when swapping sensors. For the same reason monitors never need recalibration after leaving the factory when used under normal operating conditions.


External extension Cable 
Polyurethane external fiber optic cable for harsh environments. ST connectors for trouble-free installation. High quality assembly.

3/8” NPT; oil tight; stainless steel mating. High pressure and high temperature resistant. Preinstalled on the EasyPlate.


Interface plate specifically designed for oil-filled applications. Leak-free design. Long-term reliability.


Stainless steel protective enclosure for the tank wall interface between the Easythroughs and external extension cables. Designed to protect both the ST-ST optical connections and the extension cables from the outside environment.