Quantum Model of a Laser with Nonlinear Absorption

Masahiko HIROOKA, Sigenobu Sunakawa

Ping Han

In this thesis,it is the first time to study how the nonlinear phases shift changes when considering the saturated absorption.The linear coefficient has been rectified though deduction in the light of quantum optics theory.Using the thin nonlinear medium model,transverse phase profile of a stable laser beam when it exits the nonlinear optical medium is obtained by the coupled equations.

Behjat Behroozian, Hassan Randjbar Askari

Abstract The Kerr nonlinearity and the nonlinear absorption coefficient in a four-level M-model of a GaAs cylindrical quantum dot (QD) with parabolic potential under electromagnetically induced transparency are investigated. By solving the density matrix equations in the steady-state, the third order susceptibility is obtained. Then, by using the real and imaginary parts of third order susceptibility, the Kerr nonlinearity and the nonlinear absorption coefficient, respectively, for this system are computed. The effects of the radius and height of the cylindrical QD are then investigated. In addition, the effects of the control laser fields on the Kerr nonlinearity and the nonlinear absorption coefficient are investigated.

Pierre Meystre, Murray Sargent

Chunfei Li, Jinhai Si, Yang Miao +2 more

Three typical excited-state nonlinear absorption effects in molecular systems with weak ground-state absorption (at 532 nm) are experimentally demonstrated: (a) reverse saturable absorption (RSA) caused by strong triplet first-to-second excited-state absorption in a copper phthalocyanine solution with 15-ns laser pulses; (b) RSA caused by strong singlet first-to-second excited-state absorption in a ${\mathrm{C}}_{60}$ solution with 21-ps laser pulses; (c) the RSA-SA turnover caused by strong singlet first-to-second excited-state absorption and weak singlet second-to-third excited-state absorption in a metallo-porphyrin-like solution with 21-ps laser pulses. To simulate these excited-state nonlinear absorption behaviors we propose a general ten-level density-matrix model and its simplified models for the three cases. All simulations are in good agreement with the experimental results.

Pierre Meystre, Murray Sargent