Second harmonic generation, for

Schaich W L 2000 Calculations of second-harmonic generation for a ]ellium metal surface Phys. Rev. B 61 10 478-83... 

CB04. The spontaneous polarisation was measured by the pulse pyroelectric technique (Ps = 46 nC/cm ). The piezoelectric coefficient evaluated for CB04 was dsi = 1.6 pC/N. The estimation of the efficiency of the second harmonic generation for compound CB04 gives the value three times more than for quartz. 

The NLO materials used so far are mainly inorganic materials, such as quartz, KDP, zinc oxide, LiNbOs, etc. The ions in these inorganic materials are responsible for the NLO properties. The ions have a great mass so that the NLO coefficients of these NLO materials are small at high frequency. Table 6.11 lists elements of the NLO tensors of the Pockel effect and of the second harmonic generation for some widely used NLO materials, Xp and x(d ... 

In the case of second harmonic generation, for example, the second-order susceptibility tensor elements are symmetrical in their last two indices. Therefore, the number of independent tensor elements is reduced from 27 to 18. Moreover, the tensor elements be expressed in contracted form [j The index I takes... 

FIGURE 9 Second-harmonic power development during propagation for non-phase-matched, perfectly phase-matched, and quasi-phase-matched (QPM) second-harmonic generation. For QPM, the back-conversion into the fundamental is prevented by turning off the nonlinearity every other coherence length. 

Second-harmonic generation for nonlinear optics, ferroelectricity, and piezoelectricity are all properties that are dependent on the pre.sence, magnitude, and orientation of bulk polarity in crystals and films. Therefore, the issue of how to design a polar solid from basic principles remains a challenge that has immense potential relevance to materials science. Obviously, a polar solid is guaranteed if a pure enantiomer is used as a component of a compound. However, the presence of polarity does not in any way imply that optimal packing will occur and, further-... 

An obvious disadvantage of using second harmonic generation for the spectroscopy at adsorbate-covered surfaces is the missing molecule specificity. This problem can be overcome if one mixes a fixed-frequency laser pulse with a pulse of variable frequency ("sum frequency generation", SFG). Since also vanishes in dipole approximation in media with inversion symmetry, this method has high surface sensitivity, too, and shows resonance enhancement. 

Zhu, X., Shen, Y., and Carr, R. (1985). Correlation between thermal desorption spectroscopy and optical second harmonic generation for monolayer surface coverages. Surf. Sci., 163 114 -120. 

J. S. Salafsky, Phys. Chem. Chem. Phys., 9, 5704 (2007). Second-Harmonic Generation for Studying Structural Motion of Biological Molecules in Real Time and Space. 

Aktsipetrov O A, Baranova I M and Il inskii Y A 1986 Surface contribution to the generation of reflected second-harmonic light for centrosymmetric semiconductors Zh. Eksp. Tear. Fiz. 91 287-97 (Engl, transl. 1986 Sov. Phys. JETP 64 167-73)... 

Byers J D, Yee H i and Hicks J M 1994 A second harmonic generation anaiog of opticai rotary dispersion for the study of chirai monoiayers J. Chem. Phys. 101 6233-41... 

Yan E C Y, Liu Y and Eisenthal K B 1998 New method for determination of surface potential of microscopic particles by second harmonic generation J. Phys. Chem. B 102 6331-6... 

In the single-domain state, many ferroelectric crystals also exhibit high optical nonlinearity and this, coupled with the large standing optical anisotropies (birefringences) that are often available, makes the ferroelectrics interesting candidates for phase-matched optical second harmonic generation (SHG). 

Only certain types of crystalline materials can exhibit second harmonic generation (61). Because of symmetry considerations, the coefficient must be identically equal to zero in any material having a center of symmetry. Thus the only candidates for second harmonic generation are materials that lack a center of symmetry. Some common materials which are used in nonlinear optics include barium sodium niobate [12323-03-4] Ba2NaNb O lithium niobate [12031 -63-9] LiNbO potassium titanyl phosphate [12690-20-9], KTiOPO beta-barium borate [13701 -59-2], p-BaB204 and lithium triborate... 

Materials for Frequency Doubling. Second-order NLO materials can be used to generate new frequencies through second harmonic generation (SHG), sum and difference frequency mixing, and optical parametric oscillation (OPO). The first, SHG, is given in equation 3. 

Barium sodium niobium oxide [12323-03-4] Ba2NaNb 02, finds appHcation for its dielectric, pie2oelectric, nonlinear crystal and electro-optic properties (35,36). It has been used in conjunction with lasers for second harmonic generation and frequency doubling. The crystalline material can be grown at high temperature, mp ca 1450°C (37). 

Unlike linear optical effects such as absorption, reflection, and scattering, second order non-linear optical effects are inherently specific for surfaces and interfaces. These effects, namely second harmonic generation (SHG) and sum frequency generation (SFG), are dipole-forbidden in the bulk of centrosymmetric media. In the investigation of isotropic phases such as liquids, gases, and amorphous solids, in particular, signals arise exclusively from the surface or interface region, where the symmetry is disrupted. Non-linear optics are applicable in-situ without the need for a vacuum, and the time response is rapid. 

With commercially available YDFL as pumps, powers > 40 W at 1178 nm are feasible. This sets an upper limit to the conversion efficiency needed in the subsequent second harmonic generation. Numerical simulations for the amplifier and resonator Raman laser configuration indicate feasibility of the system with sufficient SBS suppression. ESO has assembled the amplifier configuration, and has demonstrated up to 4 W CW at 1178 nm. ESO s goal is to have compact and turnkey commercial fiber lasers for LGS/AO within 3 years. 

As was proven later by Bishop [19], the coefficient A in the expansion (73) is the same for all optical processes. If the expansion (73) is extended to fourth-order [4,19] by adding the term the coefficient B is the same for the dc-Kerr effect and for electric field induced second-harmonic generation, but other fourth powers of the frequencies than are in general needed to represent the frequency-dependence of 7 with process-independent dispersion coefficients [19]. Bishop and De Kee [20] proposed recently for the all-diagonal components yaaaa the expansion... 

Table 1 Coefficients for 7[ (a ) for third harmonic generation (THG), degenerate four wave mixing (DFWM), electric field induced second harmonic generation (ESHG), and Kerr effect in methane at the experimental geometry rcH = 2.052 a.u. A CCSD wavefunction and the t-aug-cc-pVDZ basis were used. (Results given in atomic units, the number in parentheses indicate powers of ten.)...

The CCSD model gives for static and frequency-dependent hyperpolarizabilities usually results close to the experimental values, provided that the effects of vibrational averaging and the pure vibrational contributions have been accounted for. Zero point vibrational corrections for the static and the electric field induced second harmonic generation (ESHG) hyperpolarizability of methane have recently been calculated by Bishop and Sauer using SCF and MCSCF wavefunctions [51]. 

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