基于光放大的长脉冲抽运太赫兹激光

为了获得较窄增益带宽、较大光强的太赫兹辐射,尝试了利用TEA CO₂激光器对6 W可调谐连续波CO₂种子激光实行双程光放大实验,以期望获得长脉冲、高峰值功率的抽运光.通过实验,获得了大约30倍的放大系数,放大光输出功率随种子光注入功率的增加而增加,其中10 P （20）支线表现更加突出,并且被放大的激光支线半峰全宽在14 μs左右.基于这种长脉冲抽运源,建立了一种产生脉冲太赫兹的动力学模型,给出了产生太赫兹辐射的饱和抽运光强表达式,确定了抽运光的光强范围.另外, 关键词： 激光物理 长脉冲 动力学模型 太赫兹激光     

Simulation of parametric oscillation in the submillimeter range at pumping of the ZnGeP2 crystal by a train of 100-ps high-power pulses

Analysis is given for a possibility of singly resonant parametric oscillation in the submillimeter range at synchronous pumping of the ZnGeP₂ crystal by a train of 100-ps second-harmonic pulses from the CO₂ laser with the radiation energy 1.0 J. The calculation shows that using the ZnGeP₂ crystal and the second harmonic of the CO₂ laser with the energy density 1.8 J cm⁻², one can get the peak submillimeter radiation power from 3.6 to 12 MW in the range from 95 to 300 μm (1.0–3.3 THz). The expected peak power values are larger than the experimental ones obtained by other nonlinear optics methods.     

Tunable TEA CO2 laser for long-range DIAL lidar

The high-power pulse-periodic TEA CO₂ laser intended for use in the structure of mobile ground-based long-range IR DIAL lidar is developed. For achievement of the highest peak power of radiation, the system of laser excitation with a voltage of ±40 kV and effective preionization allowing one to work at high pressure of various gaseous mixtures is created. A study of energetic, temporal and spatial parameters of laser radiation for used gaseous mixtures are executed at a pressure of 0.5–2.4 atm. The pulses of laser emission with an energy more than 10 J and duration on FWHM of ∼30 ns are obtained for the case of heliumless mixtures. The maximal obtained peak power of the laser radiation is 100 MW. The maximal efficiency of the laser including the energy deposited in the glow discharge is 12.6%. At the use of the selective cavity, the laser operation at 85 emission lines of the CO₂ molecule is obtained and at 60 lines, the energy of radiation exceeded 4 J.     

Laser action in CdS by optical pumping with radiation from a CO2 laser-produced plasma

Radiation from a CO₂ laser-produced plasma has been used to produce laser action in CdS at 5260 Å. This technique compares favorably with optical pumping of CdS by 3371 Å radiation from a pulsed N₂ laser and its potential as a new source for the optical pumping of solids at short wavelengths is strongly indicated.     

Optically pumped submillimeter laser lines from CD2Cl2 using a large tunability CW CO2 laser

Twenty-five new laser lines have been obtained in the wavelength region from 155 to 830 μm by optically pumping the CD₂Cl₂ (deuterated dichloromethane) molecule with a CW CO₂ laser having a tunability range of 300 MHz. The wavelength, polarization relative to that of CO₂ pumping radiation, and offset relative to the CO₂ center frequency were determined for all of the new lines and some other already known laser emissions. For all of them we give also the relative intensity and the optimum pressure of operation. Permanent address: Depto de Física e Química da FEIS — UNESP 15.378-000 Ilha Solteira-SP, Brazil     

Multiline short pulse amplification and compression in high gain CO2 laser amplifiers

Theoretical studies are presented for the amplification and compression of multiline short pulses of CO₂ laser radiation at 10.6 μ in a high gain, CO₂ laser amplifier. A method of efficiently generating high energy, subnanosecond pulses of CO₂ laser radiation is proposed utilizing a pulse tailoring technique recently disclosed by Figueira and Sutphin.     

A high power, 1.22 mm 13C H3 laser

Pulsed power levels in excess of 5 kW at wavelengths near 1.2 mm have been obtained via optical pumping of ¹³C H₃F in a 3 m, mirrorless waveguide laser, using a CO₂ TEA laser as a source of pump radiation.     

Mathematical simulation of high-power laser systems

The energetic, spectral, and time characteristics of a high pressure CO₂ laser at high pumping level are studied. It is shown that in the free generation regime high power radiation pulses R~ 10^–8 sec in duration with a multifrequency spectrum can be obtained. Laser output characteristics are presented as functions of gas pressure, pumping energy, and resonator parameters.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 15–20, June, 1981.     

Investigation for long wavelength fir laser lines for EPR studies: New lines from CH2=CF2

The results described in this work are part of a systematic search for long wavelength laser lines to be used in high magnetic field EPR applications and in plasma diagnostic. Four new far-infrared laser lines of CH₂ = CF₂ (1,1 difluoroethylene), optically pumped by a waveguide CO₂ laser, have been discovered and characterized in wavelength, polarization relative to the pumping radiation and offset relative to the CO₂ center frequency. New measurements of polarization and offset of 5 already known laser lines are also reported. A table of all of the known CO₂ pumped FIR laser lines from this molecule is given.     

On the tunable infrared gas lasers

The high-pressure (≈ 10 atm) electrically excited molecular gas lasers with full overlapping of the rotational lines caused by high-pressure broadening are considered as a possible new type of the powerful infrared lasers with tunable frequency. For CO₂ - laser the overlapping occurs at pressures 10 ≈ 15 atm. It is experimentally shown that the transverse-excitation multiple-arc technique allows laser action at gas pressures up to 1.8 atm for CO₂ and ≈ 0.9 atm for HF-lasers.     

Stimulated Raman scattering in carbon dioxide and a measurement of time for V-T energy transfer

A weak Q-switched ruby laser (1 MW, 40 nsec, 0.015 cm^-1 linewidth) was focused into a cell (CO₂, 50 atm). The spectrum of the total output energy (40–50 MW, 25 nsec) was studied. In addition to powerful Brillouin scattering, the first stimulated Raman Stokes line of CO₂ (10 MW) and the first three anti-Stokes Raman lines were observed for the first time in pure CO₂. It was also possible to obtain coherent Raman excitation in a second CO₂ cell for pressure down to 3 atm. This last experimental result has been applied to the measurement of the time for V-T transfer in CO₂.     

A reliable high efficiency atmospheric pressure CO2 laser

A reliably operating high efficiency CO₂ laser is discussed. By adding small amounts of xylene to the laser mixture, a very homogeneous discharge can be sustained in a flowing gas system at pressures slightly above 1 atm. Maximum efficiency is 11.5% and highest energy density is 21 J/1.     

Pulsed inductive discharge CO2 laser

A pulsed inductive discharge CO₂ laser with a wavelength of 10.6 μm has been created for the first time. The excitation system of a cylindrical pulsed inductive discharge (pulsed inductively coupled plasma) in the gas mixture of CO₂:N₂:He was developed. The temporal and energy parameters of the laser radiation were investigated. The maximum inductive discharge CO₂ laser radiation energy of 104 mJ was achieved. An average power of 3.2 W was obtained at laser generation energy of 65 mJ and pulse repetition rate of 50 Hz. In the cross-section, the laser radiation had the ring shape with an external diameter of 34 mm and thickness of 4-5 mm. The measured divergence of laser radiation was 12 mrad.     

中远红外双波段激光器增益介质匹配

对中远红外双波段激光器中DF和CO2两种增益介质的匹配进行了研究。根据对DF和CO2两种增益介质分布的理论分析,发现DF相比于CO2介质增益峰值位置更靠前,激活区长度更短,据此设计加工了一台双波段激光器,使CO2气体注入孔位置可调,通过D2和CO2注入孔位置的差别来实现两种介质增益峰值位置的匹配。实验证明了这种设计是有效的,并确定了激光器共同光轴的最佳位置位于D2气注入孔下游3 mm,CO2注入孔下游33 mm处,此处双波段激光的输出功率均接近最大值。     

New FIR Laser Lines from CHD2OH Methanol

We have investigated CHD₂OH methanol as source of far-infrared (FIR) laser radiation using the optical pumping technique. Our new waveguide pulsed CO₂ laser, with peak powers as high as some kW, has allowed us to observe 12 new lines. Each of them is characterized in wavelength, relative polarization, intensity, optimum operating pressure and pump offset from the center of the exciting CO₂ line.     

Optically pumped 15.90 μm SF6 laser

Optically pumped vibrational transition lasing has been achieved for the first time in a nonlinear molecule. Laser radiation at 628.74 ± 0.02 cm^?1 was generated from SF₆ using CO₂ TEA laser excitation. The SF₆ pumping is shown to be via absorption of two photons.     

Parametric oscillation of high-power 3-THz pulse by synchronously pumped ZnGeP<Subscript>2</Subscript> crystal: Computer simulation

Possible parametric oscillation of 3-THz pulse at synchronous pumping of the ZnGeP₂ crystal by a train of short second-harmonic pulses from the CO₂ laser has been analyzed. Calculation shows that at changing laser pulse duration τ between 4 and 500 ps and correspondingly pumping energy density (0.5–3.5 J cm⁻²) THz pulse peak power varies from 3 to 70MW with maximum at τ =9 ps.     

Infrared and far-infrared laser emissions from a TE CO2 laser pumped NH3 gas

In this paper, infrared (IR) and far-infrared (FIR) laser emissions from a TE CO₂ laser pumped NH₃ gas are reported. 8 IR laser emissions near the wavelength of 12 μm were observed by using 4 different CO₂ laser lines for the pumping. 3 IR laser emissions in P-branch of vibrational-rotational band (ν₂ → G) oscillated simultaneously in two pumping cases, i.e. pumping with the R(30) or R(16) line of 9.4 μm band from the CO₂ laser. 26 FIR laser emissions (26.45 μm ～ 281.0 μm) were observed by using 12 different CO₂ laser lines, and the 10 FIR emissions of them may be new laser emissions as far as we know.     

New far-infrared emissions and frequency measurements in hydrazine

By means of a new CO₂ laser we performed a new investigation of the far-infrared laser emission spectrum of hydrazine excited by the 10P(32) and 10R(8) CO₂ laser lines. We found seven new lines and measured the frequency of four of them; moreover we measured the frequencies of two more lines previously reported in the literature with only wavelength measurements. The frequencies of the far-infrared laser emissions have been measured by means of a frequency-synthesis chain based on new InP Schottky diodes. The detected signal was beat-note generated in a Schottky diode between the far-infrared radiation, the harmonics of a 72 GHz frequency reference and a rf signal. We also characterized all of the observed lines by their polarization relative to the pumping CO₂ laser, the optimum pressure and the offset relative to the CO₂ center frequency. PACS 42.55.Lt; 42.62.Fi     

FIR Laser Lines from CH3OD: A Review

The methanol isotopic species CH₃OD has also proved to be an efficient and powerful medium to generate radiation in the far infrared (FIR) region. After the critical review of 1994, six papers have been published dealing with new FIR laser lines from this molecule. As a consequence of the use of wide tunability waveguide CO₂ lasers as well as a new pulsed CO₂ laser operating at hot and sequential bands, as of optical pumping sources, the total number of the FIR laser lines increased from 122 in 1994 to 227 today. In this communication we present an updated and complete catalogue of FIR laser lines generated from CH₃OD. Information on wavelength, offset, relative polarization, intensity, and optimum operation pressure is generally available.