Reflection grating theory at fulfillment of the second and third orders Bragg conditions

Abstract

Approximate theory of interaction of optical waves with pure reflection gratings at fulfillment of the second and third orders Bragg conditions has been developed. Expressions of the reflectance were obtained. The start-oscillation conditions in gratings with amplification were searched. It is found that reflectance zeros are near generating modes of grating with amplification in gratings without amplification and with the refractive index modulation.