Article

# Multiorder nonlinear diffraction in frequency doubling processes

Nonlinear Physics Centre, CUDOS, Research School of Physics and Engineering, The Australian National University, Canberra ACT, Australia.
(Impact Factor: 3.29). 04/2009; 34(6):848-50. DOI: 10.1364/OL.34.000848
Source: PubMed

ABSTRACT

We analyze experimentally light scattering from chi(2) nonlinear gratings and observe two types of second-harmonic frequency-scattering processes. The first process is identified as Raman-Nath type nonlinear diffraction that is explained by applying only transverse phase-matching conditions. The angular position of this type of diffraction is defined by the ratio of the second-harmonic wavelength and the grating period. In contrast, the second type of nonlinear scattering process is explained by the longitudinal phase matching only, being insensitive to the nonlinear grating period.

### Full-text

Available from: Ole Bang
• Source
• "There are also ferroelectric domains in the crystal that can be periodically poled under a high-electric field to generate reciprocal vectors compensating the phase-mismatching. Based on the periodic poling technique, the maximum effective nonlinear coefficient can be employed, and different nonlinear processes could be realized, including simultaneous frequency-doubling of different fundamental wavelengths, sum-frequency, and third-harmonic generation242526. LiNbO 3 can become a laser material when doped with active ions. "
##### Article: Recent advances in self-frequency-doubling crystals
[Hide abstract]
ABSTRACT: The self-frequency-doubling (SFD) crystal is a representative of multifunctional crystals. In recent years, SFD crystals and lasers have gained renewed attention based on the progress on SFD crystals and lasers and Nd:RECa4O(BO3)3 (RE=Y or Gd) crystals, with SFD lasers becoming commercial products. Here, we review the advances of SFD crystals and lasers, including the basic selection rules, theoretical analysis and recent progress of some potential SFD crystals and lasers. The Nd:RECa4O(BO3)3 crystals and lasers are highlighted, and their applications are also proposed and discussed, which may provide some inspiration for the further development of the SFD field and multifunctional materials.
Full-text · Article · Jan 2016
• ##### Article: Parametric wave interaction in one-dimensional nonlinear photonic crystal with randomized distribution of second-order nonlinearity
[Hide abstract]
ABSTRACT: We theoretically study the parametric wave interaction in nonlinear optical media with randomized distribution of the quadratic nonlinearity $\chi ^{(2)}$ . In particular, we discuss the properties of second and cascaded third harmonic generation. We derive analytical formulas describing emission properties of such harmonics in the presence of $\chi ^{(2)}$ disorder and show that the latter process is governed by the characteristics of the constituent processes, i.e. second harmonic generation and sum frequency mixing. We demonstrate the role of randomness on various second and third harmonic generation regimes such as Raman–Nath and Čerenkov nonlinear diffraction. We show that the randomness-induced incoherence in the wave interaction leads to deterioration of conversion efficiency and angular spreading of harmonic generated in the processes relying on transverse phase matching such as Raman–Nath interaction. On the other hand, the Čerenkov frequency generation is basically insensitive to the domain randomness.
No preview · Article · Dec 2012 · Applied Physics B
• ##### Article: Frequency Doubling by Nonlinear Diffraction in Nonlinear Photonic Crystals
[Hide abstract]
ABSTRACT: We investigate the process of second harmonic generation via the nonlinear diffraction in periodically poled nonlinear photonic crystals. We show that single pump beam excitation in such samples leads to the frequency doubled signal being emitted in a form of a cone (commonly referred to as Cherenkov radiation) and periodic pattern localized in the vicinity of the pump (Raman-Nath nonlinear diffraction). We show that the angle of the Cherenkov ring does not depends on poling pattern, whereas the Raman-Nath emission strongly depends on the poling structure. We study the dependence of the nonlinear diffraction pattern as a function of the incidence angle of the pump and find very good agreement between experiment and analytical formulas derived on the basis of the phase matching condition. The observed effects represent nonlinear generalization of optical diffraction in linear media and can find possible applications in second harmonic optical microscopy.
No preview · Article · Jun 2009