Search for content and authors
 

Fabrication of quasi-phase-matching structure in lithium tetraborate

Kensaku Maeda ,  Kozo Fujiwara ,  Satoshi Uda 

Tohoku University, Institute for Materials Research (IMR), 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan

Abstract
 The development of an all-solid-state vacuum-UV light source is essential for achieving ultrafine laser processing. Such an all-solid-state light source must be both inexpensive and maintenance free. Devices with QPM (quasi-phase-matching) structure can reduce the incoming wavelength by half. It can be achieved in structures in which the sign of the nonlinear optical coefficient is periodically reversed. This QPM structures can be formed in ferroelectric materials such as LiNbO3 and LiTaO3 by applying an external electric field. However, the converted light with vacuum-UV cannot pass through ferroelectric materials since they are opaque to vacuum-UV (wavelength: < 300 nm).

 Lithium tetraborate (Li2B4O7; LB4) has a high nonlinear optical coefficient (d33 = 0.93 pm/V), and transparent to light with wavelengths down to 160 nm. However, LB4 is not ferroelectric and thus polarization methods cannot apply to the formation of QPM in LB4. Thus, to realize a QPM structure in LB4, we propose to make a crystal with periodically inverted c-axis twin structure.

 We investigate the relationship between crystal growth directions and twin boundary orientations in LB4. When the growth direction was between <100> and <110>, (010) twin boundaries formed. In contrast, when the growth direction was between <110> and <010>, (100) twin boundaries formed. We developed a twin boundary control method based on the above relationship. The intervals of the twin boundaries are dependent on the fineness of heating method. A fabricated crystal includes 100 μm interval periodic twin boundaries and can function as a 5th-ordered QPM structure for a second-harmonic-generation of Nd:YAG laser (1064 nm). A finer periodically twinned crystal would be required to tune in shorter phase-matching wavelengths.
 

Legal notice
  • Legal notice:

    Copyright (c) Pielaszek Research, all rights reserved.
    The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
    In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/28863 must be provided.

 

Related papers
  1. Grown-in micro defects and photovoltaic characteristics of B and heavily Ge codoped CZ-Si
  2. Study on Site Occupancy of Metal Vacancy in Langasite-type Crystal with Four Elements
  3. Site structures and antisite defects of impurity-doped lithium niobate
  4. Thermodynamic analysis of impurity partitioning in colloidal crystallization
  5. Improvement of crystal quality for tetragonal hen egg white lysozyme crystals under application of an external alternating current electric field
  6. Crystal/melt interface morphology at grain boundaries of multicrystalline silicon
  7. The Effect of an External Electric Field on Phase Equilibria, Nucleation and Growth

Presentation: Oral at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, Topical Session 6, by Kensaku Maeda
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17

Submitted: 2013-03-25 10:34
Revised:   2013-04-11 14:43