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1.
Third order nonlinear optical susceptibilities χ<3> of ternary Zn1−xMgxSe and Cd1−xMgxSe crystals have been measured using standard degenerate four-wave mixing (DFWM) method at 532 nm. The nonlinear transmission technique has been applied to check if our crystals exhibit two-photon absorption. The studied Zn1−xMgxSe and Cd1−xMgxSe solid solutions were grown from the melt by the modified high-pressure Bridgman method. For both crystals the energy gap increases with increasing Mg content. In the case of Zn1−xMgxSe, it was found that the value of third order nonlinear optical susceptibility χ<3> decreases with increasing Mg content. An explanation of this behaviour results from the dependence of optical nonlinearities on the energy band gap Eg of the studied crystals. In the case of Cd1txMgxSe with low content of Mg, no response was observed for the studied wavelength since the energy gap in such crystals is smaller than the photon energy of the used laser radiation. It was also found that the value of third order nonlinear optical susceptibility χ<3> for Cd0.70Mg0.30Se is higher than for Zn0.67Mg0.33Se. This behaviour can be understood if one take into consideration that the free carrier concentration in Cd1−xMgxSe samples is about four orders of magnitude higher than that in Zn1txMgxSe ones with comparable Mg content respectively. It is commonly known that when the electric conductivity increases, the values of nonlinear optical properties increase. From the performed measurements one can conclude that the incorporation of Mg as constituent into ZnSe and CdSe crystals leads to a change of the third order nonlinear optical susceptibilities.  相似文献   

2.
Petrov  V.  Panyutin  V. L.  Tyazhev  A.  Marchev  G.  Zagumennyi  A. I.  Rotermund  F.  Noack  F.  Miyata  K.  Iskhakova  L. D.  Zerrouk  A. F. 《Laser Physics》2011,21(4):774-781
We present measurements of the transparency, refractive index dispersion, nonlinear coefficient, damage threshold, and two-photon absorption of mixed GaS x Se1 − x crystals and show that GaS0.4Se0.6 is a promising nonlinear material for down conversion of pulsed 1064 nm radiation to the mid-IR above 5 μm without significant two-photon absorption.  相似文献   

3.
Long wavelength optical lattice vibration and dielectric constants of the quaternary mixed crystal Zn1−xyMgyBexSe are investigated based on the pseudo-unit-cell mode and Born-Huang procedure. It is found that this material shows a three-mode behavior and the oscillator strength of each mode is mainly controlled by only one component. The theoretical results also show that the linear interpretation method for dielectric constants is reliable. The vibrational frequencies and the oscillator strengths of the ternary mixed crystals BexZn1−xSe, BexMg1−xSe and MgxZn1−xSe are also calculated as special cases of the quaternary mixed crystal for comparing with experiments. The calculation shows agreement with the experimental results.  相似文献   

4.
We studied the two-photon absorption coefficient (β) for cadmium diphosphide (CdP2) single crystals in the tetragonal modification vs. the polarization azimuth (φ) of the incident light for intensities close to the optical breakdown (or optical damage) threshold for the crystal (11 MW/cm2). We have established that the value of βmax = 0.16 cm/MW is reached for φ = 0, i.e., for the ordinary wave. At the lasing frequency of a ruby laser, β|| = 2.13, which suggests anisotropy of the two-photon absorption in the studied crystals. These dependences are needed for design and fabrication of quantum electronics and nonlinear optics elements whose operation is based on the use of the two-photon absorption effect for high radiation fluxes. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 1, pp. 117–121, January–February, 2009.  相似文献   

5.
We have studied third order nonlinearities, including two-photon absorption coefficient and nonlinear refractive index n 2, of GaN in below bandgap ultraviolet (UV) wavelength regime by using UV femtosecond pulses. Two-photon absorption was investigated by demonstrating femtosecond UV pulsewidth autocorrelation in a GaN thin film while femtosecond Z-scan measurements revealed information for both n 2 and . The distribution of n 2 versus wavelength was found to be consistent with a model described by the quadratic Stark effect, which is the dominant factor contributed to the nonlinear refractive index near the bandgap. Large on the order of 10 cm/GW and large negative n 2 with a magnitude on the order of several 10–12 cm2/W were obtained. The at near mid-gap infrared (IR) wavelength was also found to be on the order of several cm/GW by using two-photon-type autocorrelations in a GaN thin film. Taking advantage of the large two-photon absorption at mid-gap wavelengths, we have demonstrated excellent image quality on two-photon confocal microscopy, including two-photon-scanning-photoluminescence imaging and two-photon optical-beam-induced current microscopy, on a GaN Hall measurement sample and an InGaN green light emitting diode.  相似文献   

6.
This paper presents step by step the procedure of determination of the quantum efficiency of luminescence of Mn2+ ions in the Zn1−x−yBexMnySe crystals. The method is based on the photoacoustic spectroscopy approach. In the paper, the experimental spectra of absorbance, transmission, absorption and photoacoustic spectra of the samples are presented and analyzed from the point of view of the possibility of determination of the quantum efficiency of Mn2+ ion luminescence at room temperature. It was determined experimentally that in the investigated crystals the quantum efficiency of luminescence in the Mn2+ ions is about 35%, 40%, 32% for the absorption peaks at 430 nm, 470 nm, and 510 nm, respectively, for Zn0.75Be0.2Mn0.05Se crystal.  相似文献   

7.
吕兵  周勋  令狐荣锋  王晓璐  杨向东 《中国物理 B》2011,20(3):36104-036104
This paper carries out first principles calculation of the structure,electronic and optical properties of Be x Zn 1 x O alloys based on the density-functional theory for the compositions x = 0.0,0.25,0.5,0.75,1.0.The lattice constants deviations of alloys obey Vegard’s law well.The Be x Zn 1 x O alloys have the direct band gap(Γ-Γ) character,and the bowing coefficients are less than the available theoretical values.Moreover,it investigates in detail the optical properties(dielectric functions,absorption spectrum and refractive index) of these ternary mixed crystals.The obtained results agree well with the available theoretical and experimental values.  相似文献   

8.
The nonlinear process of two-photon interband absorption is studied in tungstate and molybdate oxide crystals excited by a sequence of high-power picosecond pulses with a wavelength of 523.5 nm. The transmission of the crystals is measured for the excitation pulse intensity up to 100 GW/cm2. The pulse intensity in the crystals initially transparent at a wavelength of 523.5 nm is strongly limited due to two-photon absorption (TPA), and the reciprocal transmission in PbWO4 and ZnWO4 crystals reaches 50–60. In all crystals, TPA induces long-lived one-photon absorption, which affects the nonlinear process dynamics and leads to a hysteresis in the dependence of the transmission on the laser excitation intensity. Absorption dichroism manifests itself in a significant difference in the transmission intensities when the principal orthogonal optical axes of the crystals are excited. The TPA coefficients are determined during the excitation of two optical axes of the crystals. TPA coefficients β for the crystals vary over a wide range, namely, from β = 2.4 cm/GW for PbMoO4 to β = 0.14 cm/GW for CaMoO4, and the values of β can differ almost threefold when different optical axes of a crystal are excited. Good agreement is achieved between the measured intensities limited by TPA and the estimates calculated from the measured nonlinear coefficients. Stimulated Raman scattering (SRS) upon excitation at a wavelength of 523.5 nm is only detected in two of the four crystals under study. The experimental results make it possible to explain the suppression of SRS by its competition with TPA, and the measured nonlinear coefficients are used to estimate this suppression.  相似文献   

9.
The third-order optical nonlinearities in undoped and Fe-doped KTA crystals have been measured using the Z-scan technique with femtosecond pulses at 780-nm wavelength. The nonlinear refractive index is determined to be 1.7×10−15 cm2/W and 0,9×10−15 cm2/W for undoped and Fe-doped KTA, respectively. No two-photon absorption occurs in these crystals. It is shown that doping with Fe2O3 could weaken refractive nonlinearity of KTA, suggesting that Fe:KTA will improve the performance of KTA in high-intensity femtosecond laser applications. In addition, the measured nonlinear index of refraction in KTA crystals is about five times lower than that predicted by the two-band theory. One of the reasons for the discrepancy is given as the applicable limit of the simple theory in which a two-parabolic band model has been assumed in the analysis. Received: 3 June 1999 / Published online: 20 October 1999  相似文献   

10.
The composition and size of optically active CdxZn1−xSe/ZnSe quantum dots are estimated with a previously developed method. The results are then compared with those obtained for CdxZn1−xSe/Zn0.97Be0.03Se QDs. We show that introducing Be into the barrier material enhances both Cd composition and quantum size effect of optically active quantum dots.  相似文献   

11.
Bi3TiNbO9 (BTN) thin films with layered perovskite structure were fabricated on fused silica by pulsed laser deposition. The XRD pattern revealed that the films are single-phase perovskite and highly (00l) textured. Their fundamental optical constants, such as band gap, linear refractive index, and linear absorption coefficient, were obtained by optical transmittance measurements. The dispersion relation of the refractive index vs. wavelength follows the single electronic oscillator model. The nonlinear optical absorption of the films was investigated by single beam Z-scan method at a wavelength of 800 nm with laser duration of 80 fs. We obtained the nonlinear absorption coefficient β=1.44×10−7 m/W. The results show that the BTN thin films are promising for applications in absorbing-type optical devices.  相似文献   

12.
Single beam z-scan measurements have been made on films containing amorphous polycarbonate and the zwitterionic chromophore, PYR-3, that has a very high second order nonlinear optical (NLO) figure of merit. The third order NLO figure of merit is ≈1.6 at 1030 nm and is comparable to that found in organic compounds optimized for high n 2 values. The two-photon absorption coefficient is 2.1×10−12 m/W, which is very low and advantageous for NLO device applications. The third order NLO refractive index is −1.4×10−18 m2/W.  相似文献   

13.
Investigations of photoluminescence and Raman scattering in the ternary Zn1-xMgxSe compounds at 4.2 K were performed both in the Stokes and anti-Stokes regions using cw laser excitation with various wavelengths within the transparency band of the crystals. The anti-Stokes luminescence was observed for the first time in the ternary Zn1-xMgxSe compounds. We have found variations in the shape and position of the Stokes and anti-Stokes luminescence bands with an increase in the band gap energy, which depends on magnesium content. We assume that the anti-Stokes emission is generated by two-step excitation via deep-level centers. It is shown that the low-temperature anti-Stokes photoluminescence can probe the spatial distribution profiles of impurities in the bulk of crystals.  相似文献   

14.
The nonlinear responses and optical limiting performance of a dye type acid, called fast green FCF, are investigated under irradiation of 35 mW continuous wave He-Ne Laser. The second order refractive index and nonlinear absorption coefficient are measured by use of z-Scan technique. The optical limiting behavior is investigated by transmission measurement through the sample. Linear absorption coefficient (α), nonlinear absorption coefficient (β) and second order refractive index (n2) of fast green FCF are measured at different concentrations.  相似文献   

15.
The nonlinear optical properties of thin films of LaEr(MoO4)3 were studied using a ∼30 ps Nd:YAG laser at 532 nm with a repetition rate of 250 Hz. Closed aperture Z-scan measurement revealed a negative nonlinearity in the LaEr(MoO4)3. The nonlinear refractive index γ=1.38×10-10 cm2/W and nonlinear absorption coefficient β=16.8×10-6 cm/W were calculated from the Z-scan data. The fluorescent upconversion spectra were recorded with 980 nm excitation. An optical switching mechanism based on nonlinear absorption is also presented experimentally. PACS 81.15.Fg; 77.84.Bw; 33.50.Dq; 42.70.Mp  相似文献   

16.
Intensity-induced nonlinear effects in optical window materials have been investigated at 308 nm. The absolute two-photon absorption coefficients for fused silica, CaF2, BaF2, Al2O3 and ADP crystals have been measured by using a single 120 ps, transform-limited pulse from the second harmonic of a distributed feedback (DFB) dye laser. The nonlinear refractive index coefficient has been obtained from measurements of far-field intensity distributions.  相似文献   

17.
Lattice constants, elasticity, band structure and piezoelectricity of hexagonal wide band gap BexZn1−xO ternary alloys are calculated using first-principles methods. The alloys' lattice constants obey Vegard's law well. As Be concentration increases, the bulk modulus and Young's modulus of the alloys increase, whereas the piezoelectricity decreases. We predict that BexZn1−xO/GaN/substrate (x=0.022) multilayer structure can be suitable for high-frequency surface acoustic wave device applications. Our calculated results are in good agreement with experimental data and other theoretical calculations.  相似文献   

18.
3 crystal have been measured using Z-scan technique with picosecond pulses at 532 nm. The nonlinear absorption coefficient and nonlinear refractive index are determined to be 2.5×10-10 cm/W and 5.3×10-15 cm2/W, respectively. Both sign and magnitude of the measured refractive nonlinearity are considerably different from the reported Z-scan results in LiNbO3 obtained with cw laser beam at 514 nm. The nonlinearities in LiNbO3 induced by 532 nm picosecond pulses are believed to be mainly due to two-photon absorption and bound electronic Kerr effect associated with the two-photon absorption. Received: 4 July 1996  相似文献   

19.
The third order nonlinear optical properties of acid blue 29 solutions have been studied using Z-scan technique. Experiments are performed using a CW He–Ne laser at 632.8 nm wavelength and 3 mW power. The linear absorption coefficient α0, nonlinear absorption coefficient β, nonlinear refractive index n2, Re χ3, and Im χ3 are measured at three different concentrations. Our results show that higher concentration gives better nonlinear optical properties. Also, it was found that there is an increasing trend in the value of the nonlinear refractive index n2 as the concentration increases.  相似文献   

20.
Fe2O3纳米微粒溶胶非线性光学特性的Z-扫描研究   总被引:3,自引:0,他引:3       下载免费PDF全文
利用Z扫描技术在透明区域研究了Fe2O3纳米微粒水溶胶和表面包覆有机溶胶的非线性光学特性,给出了非线性折射率γ、双光子吸收系数β、自由载流子折射系数σr和自由载流子吸收截面σab等重要物理参数,讨论了自由载流子效应对Fe2O3纳米微粒非线性特性的影响 关键词:  相似文献   

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