Plane-wave theory of self-doubling optical parametric oscillators

Cataloged from PDF version of article.This paper presents a theoretical analysis of selfdoubling optical parametric oscillators (OPO’s) where a single nonlinear crystal is used for both parametric generation and frequency doubling. In these devices, the parametric generation and frequency-doubling processes are both phase matched for the same direction of propagation inside the crystal. Different polarization geometries for which this simultaneous phasematching condition can potentially be satisfied are identified and categorized. Plane-wave coupled-mode equations are presented for each of these categories. Numerical solutions of these coupledmode equations and calculation of the single-pass saturated signal gain are outlined. Intracavity signal photon flux calculations based on these numerical solutions are presented. The dependence of performance measures such as the photon conversion efficiency on various design parameters are investigated

Single-crystal sum-frequency-generating optical parametric oscillator

Cataloged from PDF version of article.We report a synchronously pumped optical parametric oscillator that generates the sum frequency of the pump and the signal wavelengths. A single KTiOPO4 (KTP) crystal is used for both parametric generation and sum-frequency generation in which these two processes are simultaneously phase matched for the same direction of propagation. The parametric oscillator, pumped by a femtosecond Ti:sapphire laser at a wavelength of 827 nm, generates a blue output beam at 487 nm with 43% power-conversion efficiency. The polarization geometry of simultaneous phase matching requires rotation of the pump polarization before the cavity. Adjusting the group delay between the two orthogonally polarized pump components to compensate for the group-velocity mismatch in the KTP crystal increases the photon-conversion efficiency more than threefold. Angle tuning in conjunction with pump wavelength tuning provides output: tunability in the 484-512-nm range. A planewave model that takes group-velocity mismatch into account is in good agreement with our experimental results. (C) 1999 Optical Society of America [S0740-3224(99)01309-0]

Plane-wave dynamics of optical parametric oscillation with simultaneous sum-frequency generation

This paper presents a theoretical analysis of sum-frequency generating optical parametric oscillators where a single nonlinear crystal is used for both parametric generation and sum-frequency generation. In these devices, the parametric and sum-frequency generation processes are both phase matched for the same direction of propagation inside the crystal. Different polarization geometries for which this simultaneous phase-matching condition can potentially be satisfied are identified and categorized, for both birefringent and quasi-phase-matching methods. Plane-wave coupled-mode equations are presented for each of these categories. Solutions of these coupled mode equations and calculation of the single-pass saturated signal gain are outlined. Intracavity signal photon flux density calculations based on these solutions lead to stable steady-state upconversion, multistability, and chaos. The dependence of the photon conversion efficiency on various design parameters are investigated

Non-uniform lateral current distribution in quantum cascade lasers

Non-uniform lateral current distribution in quantum cascade (QC) lasers is investigated, as a result of stimulated-optical-emissionassisted electron transport, the rate of which depends on the local photon density and is comparable to the longitudinal optical (LO) phonon scattering rate. A microscopic model based on rate equations is built to study the self-consistent process of interaction between local electrons and photons in QC lasers. The non-uniform distribution of lateral current and the corresponding spatial hole burning are simulated from this model. Moreover, multi-transverse-mode operation in QC lasers is also investigated

Single-crystal sum-frequency-generating optical parametric oscillator

A synchronously-pumped single-crystal sum-frequency-generating optical parametric oscillator (SF-OPO) was examined. Parametric and sum-frequency generations were simultaneously phase matched within the single nonlinear KTiOPO4 crystal of the oscillator. A good plane-wave model of pulse propagation in the SF-OPO was developed. It was necessary to rotate the pump polarization before the cavity to achieve the polarization geometry for simultaneous phase matching. To defeat group-velocity mismatch in the KTP, the group delay between the two orthogonally-polarized pump components was varied, increasing photon-conversion efficiency. A record high conversion efficiency of 43% for upconversion OPO was achieved