SEDL / STP / STP954-EB / STP23142S

Two-Photon Absorption, Nonlinear Refraction and Optical Limiting in Semiconductors

Van Stryland, EW
North Texas State University, Denton, Texas

Vanherzeele, H
North Texas State University, Denton, Texas

Woodall, MA
North Texas State University, Denton, Texas

Soileau, MJ
North Texas State University, Denton, Texas

Smirl, AL
North Texas State University, Denton, Texas

Guha, S
North Texas State University, Denton, Texas

Boggess, TF
North Texas State University, Denton, Texas

Pages: 20    Published: Jan 1986

Download this paper for $25 PDF (336K)          View License Agreement
Abstract

Two-photon absorption coefficients β² of eight different semiconductors with bandgap energy E^g varying between 1.4 and 3.7 eV are measured using 1.06 μm and 0.53 μm picosecond pulses. β² is found to scale as E^−3g as predicted by theory for the samples measured. Extension of the empirical relationship between β² and E^g to InSb with E^g = 0.2 eV also provides agreement between previously measured values and the predicted β². In addition the absolute values of β² are in excellent agreement (the average difference being >26%) with recent theory which includes the effects of nonparabolic bands. The nonlinear refraction induced in these materials is monitored and found to agree well with the assumption that the self-refraction originates from the two-photon generated free carriers. The observed self-defocusing yields an effective nonlinear index as much as two orders of magnitude larger than CS² for comparable irradiances. This self-defocusing in conjunction with two-photon absorption is used to construct a simple, effective optical limiter that has high transmission at low input irradiance and low transmission at high input irradiance. The device is the optical analog of a Zener diode.