Characteristics of Ideal Optical Limiter and Realization Scenarios Using Nonlinear Organic Materials – A Review.
International Journal of Advanced Trends in Engineering and Technology (IJATET), 1(1), 73-84.
12 Pages Posted: 2 Nov 2017
Date Written: December 31, 2016
The devices used for sensor protection against laser pulses are called optical limiters. The ideal optical limiter has the characteristics has a high linear transmission for low input (e.g. energy E or power P), a variable limiting input E or P, and a large dynamic range defined as the ratio of the E or P at which the device damages (irreversibly) to the limiting input. Such devices can also be used as power or energy regulators. However, since the primary application of the optical limiter is for sensor protection, and damage to detectors is almost always determined by fluence or irradiance, these are usually the quantities of interest for the output of the limiter. Getting ideal limiting response turns out to be possible using a wide variety of materials; however, it is very difficult to get the limiting threshold as low as is often required and at the same time have a large dynamic range. Because high transmission for low inputs is desired, the material/device must have low linear absorption.These criteria lead to the use of two-photon absorption (2PA) and nonlinear refraction phenomena in practice.Any material (both inorganic or organic) which shows nonlinear absorption can be used for practical limiters.Unfortunately, except in the IR region, 2PA coefficients of inorganic solids are too small for most of these applications which look to protect against nanosecond sources. Organic materials have the potential for larger nonlinearities and are being actively investigated. In addition, if small linear absorption can be tolerated, reverse saturable absorbers can be effective. Here the transmitted fluence is reduced so that the energy of a long pulse is limited as well as a short pulse as long as the pulse width is less than excited-state decay times. In this paper, we have anslysed the characteristics of the ideal optical limiter and reviewed the recent efforts by many researchers on the realization of best optical limiter using nonlinear organic materials.
Keywords: Ideal Optical Limiters, Practical Optical Limiters, Organic Material Optical Limiters & Optical Limiters for Photonics
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