ABSTRACT
We study parametric frequency conversion in quadratic nonlinear media with disordered ferroelectric domains. We demonstrate that disorder allows realizing broadband third-harmonic generation via cascading of two second-order quasi-phase matched nonlinear processes. We analyze both spatial and polarization properties of the emitted radiation and find the results in agreement with our theoretical predictions.
Subject(s)
Light , Manufactured Materials , Models, Theoretical , Nonlinear Dynamics , Refractometry/methods , Computer Simulation , Scattering, RadiationABSTRACT
We present a new type of nonlinear mirror based on the generation of a cross-polarized wave through a nonresonant electronic third-order process. It is characterized by a reflection coefficient that depends on the input intensity. Its behavior results from the interference between the nonlinearly generated cross-polarized wave and a pi/2 phase-retarded wave. This setup has a lot of advantages: it does not require any phase matching, it is achromatic and suitable for femtosecond pulses, linear losses are easily adjustable, and the overall behavior is predictable. The device has been experimentally tested using BaF2 and YVO4 crystals.
ABSTRACT
We argue for a different physical interpretation of the results given in the recent Letter by Chvykov et al. [Opt. Lett.31, 1456 (2006)] in which a double nonlinear crystal scheme for cross-polarized wave generation is analyzed. We discuss the most important factors that explain the origin of the two-crystal scheme's increased efficiency, namely, the Kerr lensing effect and a Gouy phase shift. The position and orientation of the second crystal relative to the first one are unambiguously defined; related effects are illustrated by already published works on the subject.
ABSTRACT
We describe a method that overcomes the observed saturation effect in cross polarized wave (XPW) generation. The previously reported internal efficiencies for XPW generation are known to be limited to around 15% whatever the length of the nonlinear medium and/or the input intensity values are. At the opposite, the theoretical limit had been estimated to be close to 25%. Here we show that using two thin BaF(2) crystals separated at optimum distance the saturation level of XPW generation efficiency can be drastically increased. An internal efficiency of 30% is demonstrated experimentally using two BaF(2) crystals.
ABSTRACT
We present a simplified, potentially portable, and highly efficient blue-light source from a periodically poled KTP waveguide crystal with a compact femtosecond Cr:LiSAF laser. This light source generates 5.6 mW of blue average output power at 424 nm with 27 mW of incident fundamental in a single-pass extracavity arrangement at room temperature. The overall system efficiency of electrical power to blue light is 0.5%, and the internal second-harmonic generation conversion efficiency is as high as 37%. The slope efficiency of 5.5% pJ(-1) at low pulse energies is, to our knowledge, the highest slope efficiency yet reported for frequency conversion into the blue spectral region.
ABSTRACT
Intensity-dependent polarization rotation that results from the simultaneous action of two third-order processes, self-phase modulation and four-wave mixing, is observed. The effect is recorded along the fourfold axis of a YVO(4) crystal. The angle of rotation is proportional to the square of the input intensity-crystal length product. This is to the authors' knowledge the first experimental evidence showing that intensity-dependent polarization rotation can be related to the real part of cubic susceptibility.
ABSTRACT
A new cubic nonlinear optical effect in which a linearly polarized wave propagating in a single quadratic medium is converted into a wave that is cross polarized to the input wave is observed in BBO crystal. The effect is explained by cascading of two different second-order processes: second-harmonic generation and difference frequency mixing.
ABSTRACT
We investigate efficient fourth-harmonic generation in a single two-dimensional (2D) quadratically nonlinear photonic crystal. We propose a novel parametric process that starts with phase-matched generation of a pair of symmetric second-harmonic waves, which then interact to produce a fourth-harmonic wave that is collinear to the fundamental. We show that this process is more efficient than conventional fourth-harmonic-generation schemes by a factor that reaches 4 at low intensities and discuss how to design and optimize the nonlinear 2D photonic crystals that are implemented in LiNbO(3) and LiTaO(3) .
ABSTRACT
We introduce the concept of two-color multistep cascading for vectorial parametric wave mixing in optical media with quadratic (second-order or chi(2)) nonlinear response. We demonstrate that the multistep cascading allows light-guiding-light effects with quadratic spatial solitons. With the help of the so-called "almost exact" analytical solutions, we describe the properties of parametric waveguides created by two-wave quadratic solitons.
ABSTRACT
We have constructed a new interferometer that uses two phase-conjugate mirrors. This device allows for the measurement of the relative phase shift and the ratio of the nonlinear susceptibilities of materials. We have been able to measure weak reflectivity signals not detectable by normal degenerate four-wave mixing methods. It has been determined that the x((3)) value of colloid semiconductor glass OG530 at 532 nm is 7 x 10(-12) esu.
