Vibrational and Rotational Spectroscopy of 13CD3OD

We have used Fourier Transform spectral data on the C-O stretching mode of ¹³CD₃OD in order to perform a vibro-rotational analysis for this molecule. We have estimated a few molecular parameters of the ground and C-O stretching vibrational modes. Based on these parameters, and by using the Kwan-Dennison model, we propose assignments for a number of far-infrared laser transitions of ¹³CD₃OD.     

New FIR laser lines from an optically pumped far-infrared laser with isotopic 13C16O2 pumping

A ¹³C¹⁶O₂ laser optically pumping a FIR laser has resulted in 17 new FIR cw emissions from 78.5 μm to 917 μm. The FIR media were: CD₃OD, CH₃OD, CD₃OH, NH₃ and ¹⁵NH₃. Interesting effects have been observed with a combination of NH₃ and CD₃OD resulting in a new FIR emission. Two new FIR emissions at 181.5 μm and 355.5 μm have been observed with a ¹²C¹⁶O₂ laser optically pumping CD₃OD.     

Dual-wavelength competitive output in Nd:Y3Sc1.5Al3.5O12 ceramic disk laser

In this paper, we demonstrated a dual-wavelength competitive output in Nd:Y₃Sc_1.5Al_3.5O₁₂ ceramic disk laser. Different dual-wavelength output behaviors for Nd:YSAG and Nd:YAG ceramic disk laser were investigated and discussed. By applying the energy transfer model, we suggested the reasonable explanation for this new phenomenon as the disordered replacing of Al³⁺ ions by Sc³⁺ ions. The main advantage of the dual-wavelength ceramic laser is the possibility to serve as the seed source to generate Terahertz radiation.     

Infrared Optoacoustic Spectroscopy of CHD2OH Around 10R and 10P CO2 Laser Lines

In this work we present results of an investigation on Doppler limited infrared absorbing transitions of CHD₂OH by optoacoustic detection. It is an alternative and attractive technique to be applied to this methanol isotopomer, in comparison to Fourier transform spectroscopy. Using a waveguide CO₂ laser of 290 MHz tunability on each line, we were able to observe 60 IR absorptions, most of them of large offset. The data will be useful in the theoretical analysis of this molecule, as well as in the generation of far-infrared (FIR) laser radiation in optically pumped molecular lasers.     

Infrared Optoacoustic Spectroscopy of 13CD3OD Around 9P CO2 Laser Lines

In this work we present the results of an investigation about Doppler limited infrared absorbing transitions of the in-plane methyl-rocking and the asymmetric methyl deformation modes of ¹³CD₃OD by means of optoacoustic detection. This is an alternative and attractive technique to be applied to this methanol isotopomer, in comparison to Fourier transform spectroscopy. In fact the contamination problem associated with the fast exchange of OD by OH in the molecule limits the use of the Fourier transform technique. Using a waveguide CO₂ laser of 290 MHz tunability on each line we were able to observe 20 IR absorptions, most of them of large offset. The data will be useful in theoretical analysis of this molecule, as well as in the generation of FIR laser radiation in optically pumped molecular laser.     

New far infrared laser lines obtained by optically pumping13CD3OD

We have obtained laser action on 34 far infrared lines for the first time in fully deuterated methyl alcohol with the¹³C isotope (¹³CD₃OD), and we have measured the frequency of 13 lines. The molecule was pumped by a cw CO₂ laser. We have measured the wavelength, the relative polarization, the relative intensity of most lines, the frequency, and the CO₂ pump frequency offset of the strongest lines. The new lines are distributed in the wavelength region from 75.27 m to 464.7 m.Supported in part by a joint grant with the U.S. National Science Foundation grant # INT 80-19014 and the Brazilian Conselho Nacional de Pesquisas (CNPq).     

New N2O laser band in the 10 μm wavelength region

Fifty new laser lines have been observed in continuous emission from an N₂O laser by placing a hot N₂O absorber cell inside the laser cavity to suppress the regular laser lines. The new lines are identified as rotation-vibration transitions of the (00⁰2–10⁰1) band of N₂O.     

13CD3OH and12CD3OH optically pumped by a13CO2 laser: Observations and assignments of FIR laser lines

In this work we report the first observation of FIR laser lines from¹³CD₃OH pumped by the¹³CO₂ isotope laser. Using the same pump we have also found 3 new lines from¹²CD₃OH. Tentative assignments for the absorption and emission transitions of the observed lines are also proposed.Work supported by FAPESP. CNPq, FAEP/UNICAMP-Brasil and NSF-USA     

Infrared-to-Ultraviolet upconversion luminescence of La0.95Yb0.49Tm0.01F3 nanostructures

In this work, we used the hydrothermal method to synthesize Yb³⁺ and Tm³⁺ doped LaF₃ nanostructures, which is an ultraviolet upconversion luminescent material. Two distinct shapes such as nanosheets, nanoparticles and bulk samples formed in the products by adjusting the concentrations of the surfactant of the reaction solution. Powder X-ray diffraction analysis showed that the products were pure hexagonal phase, while electron microscopy measurements confirm the formation of different morphologies. These nanostructures exhibit strong ultraviolet upconversion luminescence under the excitation of a 978-nm diode laser. In Yb³⁺ and Tm³⁺ codoped LaF₃ materials, the relative intensity of ultraviolet and blue upconversion emissions became stronger as the size and morphology of sample changed from bulk to sheets.     

New Optically Pumped FIR Laser Lines and Frequency Measurements from CH3OD

This work reports the discovery of 45 new optically pumped far-infrared (FIR) laser lines from CH₃OD in the range 42.6 m to 207.2 m. A highly efficient CO₂ laser was used as the pump laser for an Optically-pumped Fabry-Perot FIR laser. The frequencies of most of the new lines were measured in the range 1.7 to 6.4 THz. Twenty-eight CO₂ lines were used as pump lines; nineteen of these had frequencies lower than those previously used to pump CH₃OD in a FIR laser. Sixteen of the new FIR lines had absorption transitions which belong to the OD bending vibrational mode.     

Reduction effect on the optical properties of Sm doped in SrB4O7 and SrB6O10 crystals

Reduction effects on the optical properties of Sm²⁺ ions doped in SrB₄O₇ and SrB₆O₁₀ crystals were studied by measurements of luminescence intensity decay as a function of time, X-ray irradiation and laser power effects on the photoluminescence. The fluorescence intensity of Sm²⁺ doped in SrB₄O₇ and SrB₆O₁₀ crystals decreased upon excitation at 488 nm of Ar⁺ laser and this so-called photo-bleaching effect was highly dependent on the sample preparation conditions. The fluorescence intensity of Sm²⁺ doped in SrB₄O₇ decreased about 13%, while it decreased about 55% in the SrB₆O₁₀ crystal irradiated with X-ray for 10 h. Differences of photo-beaching effect and other optical properties of Sm²⁺ doped in SrB₄O₇ and SrB₆O₁₀ are discussed.     

Enhancement of second-order optical nonlinearity in photo-darkened Ge25Sb10S65 chalcogenide glass by femtosecond laser light

The second-order optical nonlinearity of poled Ge₂₅Sb₁₀S₆₅ chalcogenide glass was found to be 40-50% larger after femtosecond laser irradiation. The highest χ⁽²⁾ was 11.4 pm/V. Raman spectral change indicated that centrosymmetric defects were created by fs light. These defects promoted the third-order optical nonlinearity of the glass and as a result, its second-order nonlinearity was also enhanced. The study shows that fs laser modification is an effective method of increasing the optical nonlinearity of photonic materials.     

A review of optically pumped far-infrared laser lines from methanol isotopes

The technique of optical pumping in polar molecules is the most efficient for Far-Infrared (FIR) laser generation, providing also a versatile and powerful tool for molecular spectroscopy in this spectral region. Methanol (CH₃OH) and its isotopic varieties are the best media for optically pumped FIR laser, with over thousand lines observed, and the most widely used for investigations and applications. In this sense, it is important organize and make available catalogues of FIR laser lines as complete as possible. Since the last critical reviews of 1984 [1] on methanol and its isotopic varieties [2,3,4], over hundred papers have been published dealing with hundreds of new FIR laser lines. In 1992 a review of FIR laser lines from CH₃OH was presented [5]. In this communication we extend this work to the other methanol isotopes, namely CH₃OD, CD₃OH, CD₃OD,¹³CH₃OH,¹³CD₃OH,¹³CD₃OD, CH₃ ¹⁸OH, CH₂DOH, CHD₂OH and CH₂DOD.Work supported by FAPESP, CNPq, FAEP-Brasil, and CNR-Italia     

IR operated novel Ag0.98Cu0.02GaGe3Se8 single crystals

In this work, we report on the structural and optical properties of novel Ag_0.98Cu_0.02GaGe₃Se₈ single crystals that were synthesized by the Bridgman–Stockbarger technique. We have performed illumination by 10.6 μm CO₂ pulsed laser working in the microsecond time duration regime. Such illumination allows causing substantial changes for both pure electronic nonlinear optical effects like optical second harmonic generation as well as piezooptical effects described by the fourth rank tensors. The measurements of the piezo-optical effects were carried out at different temperatures. The effects are observed only during the IR CO₂ laser illumination and are disappeared after switching off the illumination. Simultaneously the IR induced optical second harmonic generation at Er:glass laser fundamental wavelength 1540 nm was performed during illumination by nanosecond Nd:YAG and Er³⁺:glass laser. The observed effects allow to use the studied materials as promising for IR-optoelectronic devices.     

Efficient Nd:Y0.5Gd0.5VO4-KTiOPO4 green laser under diode pumping into the emitting level 4F3/2

We report a green laser at 532 nm generation by intracavity frequency doubling of a continuous wave (cw) laser operation of a 1064 nm Nd:Y_0.5Gd_0.5VO₄ laser under diode pumping into the emitting level ⁴ F _3/2. A KTiOPO₄ (KTP) crystal, cut for critical type-II phase matching at room temperature is used for second harmonic generation (SHG) of the laser. At an incident pump power of 17.8 W, as high as 4.21 W of cw output power at 532 nm is achieved. The optical-to-optical conversion efficiency is up to 23.6%, and the fluctuation of the green output power was better than 2.8% in the given 30 min.     

Analysis of femtosecond laser ionization/dissociation of polyatomic molecule C6H10O from one-colour pump-probe measurement

This paper reports that a one-colour fs pump-probe measurement has been carried out for studying photoionization/photodissociation of cyclohexanone (C6H10O) in intense laser field. Two of the fragments from cyclohexanone, C2H3+ and C3H3+ , are studied under 800 nm laser pump-probe and the results obtained show similar time evolutions. It proposes a feasible model for analysing the experimental observations of the one-colour fs pump-probe measurement. The results demonstrate that as an intermediate product, the excited molecular parent ions play a very important role in photionization/photodissociation processes in intense laser field.     

Far infrared laser lines produced by methanol and its isotopic species: A review

Methanol (CH₃OH) is considered today one of the most important active media for the generation of laser radiation in the far-infrared (FIR) spectral region. Together with ten of its other isotopic species, it is responsible for the major part of the laser lines generated by the optical pumping technique. Due to the extreme importance of those molecules as laser generators, we understood that there was a necessity of a comprehensive work which would include as much pratical information as possible about each line.Chang et al⁽¹⁾ early recognized methanol as a source of strong FIR laser lines. Since then, more than 100 papers were published containing information about new laser emission. Recently, Moruzzi et al⁽¹¹⁴⁾ presented a review of 575 lines produced by¹²CH₃OH. In the present paper, we have extended the review to the various isotopic modifications of this molecule (namely¹³CH₃OH, CD₃OH,¹³CD₃OH, CD₃OD,¹³CD₃OD, CH₃OD, CH ₃ ¹⁸ OH, CH₂DOH, CH₂DOD and CHD₂OH), a total of nearly 2000 lines with wavelengths ranging from 19µm to 3030µm.     

Far infrared laser frequencies of CH3OD and N2H4

The frequencies of 26 laser lines with wavelengths between 57 and 534 m have been measured in the optically pumped laser gases CH₃OD and N₂H₄. A pair of stabilized cw 12_{CO 2} lasers was used as a frequency standard for the heterodyne frequency measurements. Seven of the 26 lines are new.     

Yb3+:Gd2SiO5晶体的结构和光谱性能

采用提拉法成功生长尺寸为φ30 mm× 75 mm的15at.%Yb³⁺:Gd₂SiO₅单晶, 并用Reitveld全谱拟合方法确定了其晶格常数、原子坐标和温度因子等参数. 用吸收光谱计算了Yb³⁺离子²F_7/2↔ ²F_5/2能级跃迁的振子强度、谱线强度、跃迁概率、 能级寿命和积分发射截面等光谱参数, 并根据激光性能评估得出结论: 表明该晶体具有较大的阈值特性, 有望采用大功率激光二极管泵浦实现可调谐或超快激光输出.     

Far-infrared absorption spectra of water vapor H216O and isotopic modifications

Far-infrared absorption spectra of H₂¹⁶O, H₂¹⁸O, H¹⁶OD, H¹⁸OD, D₂¹⁶O, D₂¹⁸O have been observed between 10 and 40 cm^?1 at a resolution of 0.07 cm^?1. Experimental and calculated line positions agree within the accuracy of the experiment (±0.003 cm^?1). The relative intensities of type a and type b transitions of H¹⁶OD and H¹⁸OD are used to estimate the ratio $\text{μ}{}_{\mathrm{a}}\text{μ}{}_{\mathrm{b}}$.