Modeling of self-frequency-conversion lasers in rare-earth doped optical superlattice crystal

摘要

Recently attention has been focused on quasi-phase-matched self-frequency-conversion (SFC) laser generation in rare-earth-doped optical superlattice crystals, mainly because of their ability to generate multicolor lasers simultaneously across the visible portion of the spectrum through a single crystal. We present a general model for quasi-phase-matched SFC lasers in rare-earth-doped optical superlattice crystals that we fabricated by combining quasi-phase-matching theory and self-sum-frequency mixing (or self-frequency doubling) laser patterns. This model takes into account the TEM00 distribution of Gaussian beams with loose focusing, absorption, and coupling of pump beams and the effects of imperfect periodic structures. We analyze two types of errors, random period errors and linearly tapered period errors, in the periodicity of these structures to determine their effects on SFC laser properties (e.g., on effective nonlinear coefficients and phase-matching curves). Finally the model is applied to simulate SFC laser generation in a Nd3+ doped aperiodically poled lithium niobate crystal. By choice of one set of parameters, the calculated results, especially for threshold, total visible laser output power, and spectrum of relative laser intensity in the visible, explain the experimental phenomena in detail and indicate the validity of this model. Most significantly, the model presented makes understandable the simultaneous laser generation of multiple visible wavelengths (686, 605, 542, 482, 441, and 372 nm) from a single crystal. (C) 2002 Optical Society of America. [References: 14]