Abstract

We present a detailed characterization of optical limiting devices, i.e., devices which have a high linear transmittance at low incident irradiance (energy) which switches to low transmittance at high incident irradiance (energy). The principle of operation is based on the combined effects of two-photon absorption (2PA) and the subsequent defocusing due to the photogenerated carriers. As the 2PA coefficient is nearly constant over a large frequency range,¹ the limiter is a broadband device. The limiter is an advance on previous designs,² as damage is prevented by utilizing nonlinear propagation in an optically thick medium. By focusing tightly into the bulk of the semiconductor ZnSe with 532-nm, 30-ps pulses, we have observed limiting energies as low as 10 nJ. At high input energies, the nonlinearities prevent damaging irradiances being reached in the bulk. The dynamic range is therefore limited only by damage at the input surface of the semiconductor.

© 1986 Optical Society of America