• Title/Summary/Keyword: Phase-matching temperature

Search Result 39, Processing Time 0.021 seconds

Efficient Second Harmonic Generation of Pulsed Nd-YAG Laser Radiation with Noncritically Phase-Matchable $LiNbO_3$ in Room-Temperature

  • Jong-Soo Lee;Bong-Hoon Kang;Bum Ku Rhee;Chong-Don Kim;Gi-Tae Joo
    • The Korean Journal of Ceramics
    • /
    • v.6 no.3
    • /
    • pp.206-208
    • /
    • 2000
  • 0.65 mol% MgO-doped LiNbO$_3$single crystals were grown by CZ method. The obtained single crystals were colorless and transparent. Noncritically phase-matched second harmonic generation (SHG) of 532-nm radiation from 1064-nm in MgO-doped LiNbO$_3$has been investigated by using pulsed Nd:YAG laser. The phase-matching temperature was room temperature. SHG conversion efficiencies were typically achieved higher than 50% at the phase-matching temperature with no photorefractive damage in the region of fundamental power density which was used in this experiment. The thermo-birefringence coefficient and the electro-birefringence coefficient of SHG were calculated from the temperature phase-matching profile with the electric field.

  • PDF

Optical Parametric Oscillation in Periodically Poled Lithium Niobate Crystal (주기적으로 분극반전된 $LiNbO_3$ 결정에서 광매개증폭)

  • Kim Hong-Gi;Cha Myeong-Sik;Lee Beom-Gu
    • Proceedings of the Optical Society of Korea Conference
    • /
    • 2001.02a
    • /
    • pp.222-223
    • /
    • 2001
  • Optical parametric oscillator(OPO) has been used to generate coherent and tunable laser source with birefringent phase-matching technique in various nonlinear materials. In birefringent phase-matching, the output wavelength is controlled with angle or temperature tuning of the refractive index. However these tuning methods have several limitations such as restriction of tuning wavelength due to reasonable angular and temperature tuning ranges, Poynting vector walk-off which limits the interaction length, and thermal stabilization time. (omitted)

  • PDF

Study of poling condition in 2 mole% MgO-doped $LiNbO_3$ using second harmonic generation (제2고조파 발생특성을 통한 MgO가 2 mole% 첨가된 $LiNbO_3$ 단결정의 poling 조건연구)

  • 이종수;이범구;주기태
    • Korean Journal of Optics and Photonics
    • /
    • v.8 no.5
    • /
    • pp.377-381
    • /
    • 1997
  • Poling condition in 2 mol% MgO-doped $LiNbO_3$ crystals is investigated by varying the amplitude of poling electric field from 3V/cm to 7V/cm. It is found that 5V/cm is the best value for the formation of single domain by analysing the characteristics of the second harmonic generation(SHG) as the function of temperature. The temperature dependence of the phase-matching profile of SHG for the crystal applied by a spatially modulated electric field is observed to be very different from the simple sinc function. The distorted profile can be consistently fitted with the numerical simulations. This shows that the crystal homogeneity can be tested by the SHG temperature phase-matching profile. In addition, the thermo birefringence coefficient and electro birefringence coefficient of SHG were measured from the temperature dependence of phase-matching profile and shifts of phase-matching temperature by appling electric field along c-axis.

  • PDF

Birefringence measurements of lmol%Mg:LiNbO3 with Noncollinea­rphase­matching cone

  • Lee, Jong-Soo;Rhee, Bum-Ku;Joo, Gi-Tae
    • Journal of the Optical Society of Korea
    • /
    • v.2 no.2
    • /
    • pp.54-57
    • /
    • 1998
  • A noncollinear-phase-matching cone of second harmonic generation(SHG) was observed in a LiNbO3 crystal doped with l mol% MgO. Birefringence refractive indices can be accurately evaluated by analysing the temperature phase matching characteristic for SHG combined with the measurement of the half cone angle. The electro-optic coefficient can also be determined form the observed change of the half cone angle when a DC electric field is applied along the optic axis.

Investigation of Terahertz Generation from Bulk and Periodically Poled LiTaO3 Crystal with a Cherenkov Phase Matching Scheme

  • Li, Zhongyang;Bing, Pibin;Yuan, Sheng;Xu, Degang;Yao, Jianquan
    • Journal of the Optical Society of Korea
    • /
    • v.19 no.3
    • /
    • pp.297-302
    • /
    • 2015
  • Terahertz (THz) wave generation from bulk and periodically poled $LiTaO_3$ (PPLT) with a Cherenkov phase matching scheme is numerically investigated. It is shown that by using the crystal birefringence of bulk $LiTaO_3$ and a grating vector of PPLT, THz waves can be efficiently generated by difference frequency generation (DFG) with a Cherenkov phase matching scheme. The frequency tuning characteristics of the THz wave via varying wavelength of difference frequency waves, phase matching angle, poling period of PPLT and working temperature are theoretically analyzed. The parametric gain coefficient in the low-loss limit and the absorption coefficient of the THz wave during the DFG process in the vicinity of polariton resonances are numerically analyzed. A THz wave can be efficiently generated by utilizing the giant second order nonlinearities of $LiTaO_3$ in the vicinity of polariton resonances.

Effect of Chain Matching between Hydrocarbon and Fatty Acid on High Pressure Rheology

  • Ohno, N.;Mukai, R.;Rahman, Md.Z.;Shibata, K.
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
    • /
    • 2002.10b
    • /
    • pp.83-84
    • /
    • 2002
  • For estimation of chain-matching phenomena between normal paraffin as a solvent and straight-chain fatty acid as an additive, the density measurement of n-dodecane, n-tetradecane and n-hexadecane were carried out at oil temperature 313K and pressure up to 1.3 GPa. Their solidification pressure were easily determined by the appearance of molecular crystal, abrupt volumetric contraction and generation of heat of solidification and showed minima under the matching condition. The bulk modulus K of molecular crystal was evaluated using phase diagram. The bulk modulus showed maxima under the each matching condition. The chain matching effect on the bulk modulus beyond the scope of the interfacial phenomena are confirmed.

  • PDF

Theoretical Investigation of the Generation of Broad Spectrum Second Harmonics in Pna21-Ba3Mg3(BO3)3F3 Crystals

  • Kim, Ilhwan;Lee, Donghwa;Lee, Kwang Jo
    • Current Optics and Photonics
    • /
    • v.5 no.4
    • /
    • pp.458-465
    • /
    • 2021
  • Borate nonlinear optical crystals have been used as frequency conversion devices in many fields due to their unique transparency and nonlinearity from ultraviolet to visible spectral range. In this study, we theoretically and numerically investigate the properties of broadband second harmonic generation (SHG) in the recently reported Pna21-Ba3Mg3(BO3)3F3 (BMBF) crystal. The technique is based on the simultaneous achievement of birefringence phase matching and group velocity matching between interacting waves. We discussed all factors required for broadband SHG in the BMBF in terms of two types of phase matching and group velocity matching conditions, the beam propagation direction and the corresponding effective nonlinearity and spatial walk-off, and the spectral responses. The results show that bandwidths calculated in the broadband SHG scheme are 220.90 nm (for Type I) and 165.85 nm (for Type II) in full-width-half-maximum (FWHM). The central wavelength in each case is 2047.76 nm for Type I and 1828.66 nm for Type II at room temperature. The results were compared with the non-broadband scheme at the telecom C-band.

The relation between optical diffraction pattern and domain size in blue phase

  • Lee, Ho-Hyun;Kim, Jong-Hyun;Kikuchi, H.
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2009.10a
    • /
    • pp.942-944
    • /
    • 2009
  • Blue phase shows several different reflection colors from the randomly oriented domains and crystal direction. Also there are variations in the size of domains. The domain size is dependent on the temperature gradient. With smaller cooling rate of temperature, the domain size was increased compared with rapid cooling. With injection of light of specific wavelength, we find that the diffraction patterns were occurred around the light spot in the cell of blue phase. It was supposed to be from the matching of the phase retardation and domain size. However, actually the diffraction pattern is reflecting the lattice structure in double twist of the blue phase. The lattice constant from the radius of diffraction patterns shows very similar one from the reflection spectrum, which indicates the internal lattice constant in double twist of the blues phase.

  • PDF

Power Characteristics of cw Second-harmonic Generation in Periodically Poled LiNbO3

  • Kang, Bong-Hoon;Joo, Gi-Tae;Rhee, Bum-Ku
    • Journal of the Korean Ceramic Society
    • /
    • v.47 no.5
    • /
    • pp.430-432
    • /
    • 2010
  • We verified through a noncritical phase-matched second-harmonic generation experiment that the periodically-poled $LiNbO_3$ (PPLN) had a large effective nonlinear optical coefficient, demonstrating that the QPM grating was uniform throughout the entire length of PPLN. The quasi-phase matching temperature was $193.4^{\circ}C$. The maximum SHG output power at the fundamental power of 2.0 W was found to be 18.0 mW; generated second-harmonic beam was found to have no photorefractive effect.

Resonant Wavelength Characteristics of Arc-Induced Long-Period Fiber Gratings (아크 유도 장주기 광섬유 격자의 공진 파장 특성)

  • Chung, Chul;Lee, Ho-Joon
    • Journal of the Institute of Electronics Engineers of Korea SD
    • /
    • v.39 no.10
    • /
    • pp.48-56
    • /
    • 2002
  • A fabrication method of long--period fiber gratings (LPFGs) that can be easily controlled resonance wavelength and losses is introduced. We used the superposition method that core and cladding diameter are modulated by applying a number of small electric-arc to the normal fiber. We derived an equation of resonance wavelength change according to core diameter variation using the phase matching condition and showed the results are well matched with experiments. The measured resonant wavelengths of arc-induced superposition LPFGs according to grating period are well coincident with that of phase matching condition. The resonance wavelength is measured for the temperature changes and a slight mechanical strength degradation of arc-induced LPFGs is observed by increasing arc times.