CW Discharge‐Pumped DCN Laser with Novel Mixture Gas

This paper describes a CW submillimeter waveguide discharge‐pumped DCN laser operating on 190 and 195μm lines with novel mixture gas(N₂, CD₄, and D₂). No brown polymer deposit was found after long time discharge even at low wall temperature. The laser discharge length is 3 m, and the resonator length is 3.4 m. The resonator cavity consists of a pyrex tube of 54 mm diameter and two plane reflectors against its ends, one is a plane mirror, the other is a metal mesh. After optimization of various parameters, such as the N₂:CD₄:D₂ gas mixture, the discharge current and the wall temperature, this laser delivers 150 and 160mW on the 190 and 195μm lines, respectively, for EH₁₁ mode.     

太赫兹连续波DCN激光器的实验研究

介绍了运行在1.54THz(195μm)和1.58THz(190μm)的波导型辉光放电激励的大功率连续波DCN激光器的开发和研制工作.该激光器的谐振腔长3.4m,放电长度3m,谐振腔由耐热玻璃制成,直径54mm.谐振腔一端为平面反射镜,一端为金属栅网.工作气体为N2,CD4和He(或D2)的混合气体,在1.54THz的连续激光输出功率大于0.2W.实验中对放电电流、激光管温度、气压等参数进行了优化,研究了EH11模DCN激光在自由空间的传输特性.研究表明,利用新的N2,CD4和D2混合气体的太赫兹DCN激光器可以得到稳定连续的高功率放电.光束传输远场满足高斯分布(z>4m),对各种参数进行优化后,190μm和195μm窗口处输出EH11模功率分别为0.15W和0.16W,可以满足超导托卡马克连续运行的干涉测量的需要.     

Optimization and Maximum Output Power of CW DCN Laser

A high power CW 195 μm DCN laser has been developed for fusion plasma diagnostics. Optimization of various parameters (such as the rate of N₂:CD₄:He gas mixture, the gas pressure and the discharge current, the wall temperature and the output couple) for maximum output power at the DCN laser were performed and reported in this paper. Output power of about 220 mW on the 195 μm line has been obtained with 3.4 m long and 54 mm inner diameter discharge-pumped wave-guide laser. A new mixture gas of N₂:CD₄:D₂ was used in producing a stable high-power discharge and preventing the deposition of brown polymer with lower wall temperature and discharge current.     

Simultaneous two wavelength operation of an optically pumped HCOOH laser on orthogonally polarized modes

Simultaneous laser operation in orthogonally polarized EH₁₁ and TE₀₁ waveguide modes is reported for pairs of cascade lines from an optically pumped formic acid vapour laser incorporating a strip grating output coupler. Observations were made for the 394 μm/406 μm and 433 μm/446 μm cascade sequences, the resonator length being adjusted so that the laser was simultaneously resonant on a mode of the primary transition polarized perpendicular to the strips of the output coupler and the same transverse mode of the secondary transition polarized parallel to the coupler strips. Power measurements showed that for the laser configuration used in this study the power of the primary transition was increased only slightly when the cascade lines were simultaneously resonant, whereas the secondary line could only lase under these conditions.     

Assignment and frequency of C18O2 pumped fir laser lines in12CH3F using infrared diode laser spectroscopy

Optically pumped FIR laser lines in¹²CH₃F at 186.6 and 497.4μm have been assigned using high resolution diode laser spectroscopy. Accurate calibration of diode laser spectra of CH₃F using CO₂ laser lines yields the laser wavenumbers: $$\begin{gathered} 186.6 \mu m laser:53.5250cm^{ - 1} \hfill \\ 497.4 \mu m laser:20.1250cm^{ - 1} \hfill \\ \end{gathered}$$ These are in good agreement with values calculated from spectroscopic parameters by Arimondo and Inguscio and with a direct frequency measurement.     

Wavelengths for new CH3OH laser lines

Using a grating-tuned CO₂-TEA laser to pump CH₃OH in a metallic-wave-guide resonator, submillimeter laser emissions have been produced by pumping with 36 lines in the 9.4μm CO₂ band and with 23 lines in the 10.6μm band. Several dozen new SMM laser lines were observed. Wavelengths accurate to within ～0.1% are given for 12 previously unmeasured lines between 34μm and 225μm.     

Submillimeter emission lines from CD2Cl2 optically pumped lasers

Fifty-five new submillimeter laser lines from optically pumped CD₂Cl₂, have been obtained in a FIR metallic waveguide resonator. Twenty-seven lines, ranging from 184 μm to 1387 μm, and twenty-eight lines, from 219 μm to 888 μm, have been observed when using CW CO₂ laser and CW N₂O laser optical pumping, respectively. The accuracy of wavelength measurements are of the order of 3.10^?3.     

The Beam Property of DCN Laser

In this paper the lasing modes and the propagation property of a CW DCN laser, which cavity is a 50 mm inner diameter with length of 3.4 m, were studied. The modes of 195 and 190 μm lines are well identified by the micrometer mount of the movable mirror in one end of the cavity. The beam profile is found to be qualitatively Gaussian in the far-field (Z > 4 m).     

A compact fir ring laser with open resonator and variable output coupling

We describe the design, construction and first experimental results with an open triangle FIR ring resonator with Michelson interferometer output coupling, which we combined with a Brewster-windowless 10W CO₂ pump laser to a compact laser package of 1m length. The achieved stability of power and frequency of this system is very high, typically on the order of ±0.01% over several hours and <20kHz per hour at 800GHz. For the design, we investigated the balance of all laser processes and determined the optimum dimensions for the open resonator cavity. This analysis is based on a radially homogenous overall laser model, including commonly accepted simplified rate equations together with molecular parameters for weak FIR laser lines. In accordance with the modelling the efficiency on the very most prominent lines is better than with conventional waveguide lasers, giving up to ≈4 times better efficiencies especially on lines with low absorption pump transitions. Several laser lines, however, have substantially enhanced pump thresholds on purely copropagating emission, suppressing laser operation below about 10W pump power threshold. We show that this can not be due to effects from the interferometer.     

High power FIR NH3 laser using a folded resonator

A compact FIR laser cavity having a couple of folding mirrors was designed. By inserting this FIR cavity into the pump TE CO₂ laser resonator, we observed 19 FIR NH₃ laser lines of which 4 new lines were included. The maximum output power was over 500 W at 90 μm.     

New FIR laser lines and frequency measurements in CD3OD

Twenty-four new submillimeter laser lines in fully deuterated methyl alcohol (CD₃OD) in the wavelength range from 52 to 328 μm have been obtained in a Fabry-Perot FIR resonator by optically pumping the methanol with a cw CO₂ laser. We have made accurate wavelength measurements and have determined the relative polarization of most of the known CD₃OD laser lines. The frequencies of 13 of the strongest lines were also measured.     

A CW 28 μm water vapor laser for plasma diagnostics

A high-power CW 27.972 μm water vapor laser has been constructed in order to use as a light source of an interferometer for plasma diagnostics. The laser consists of 220 cm length and 2.0 cm small bore Pyrex glass discharge tube, semi-confocal resonator and Michelson coupler. From the measurement of cavity detuning curves, it is found that two waveguide modes, EH₁₁ and EH₂₁ oscillate. The increase of the output power is found to become more than seven times larger by adding He(50%)?H₂(50%) mixed gas. Under the optimum condition, the maximum output power of 65 mW or the output power per unit cavity volume of 83 μW/cm³ is obtained.     

New cw FIR laser lines from optically pumped silyl fluoride (SiH3F)

FIR laser action has been observed for the first time in a molecule containing silicon: silyl fluoride, SiH₃F. Eleven new cw optically pumped lines between 187 and 1014μm were detected from both open resonator and waveguide structures. Although the chlorine analogue, SiH₃Cl, showed strong absorption at every CO₂ laser frequency no FIR laser emission was detected at the pump powers available.     

High repetition rate CH4 laser

A 16-μm CF₄ laser oscillator has operated at 1 kHz in a cooled static cell. Pump energies required from the low pressure, Q-switched, cw discharge CO₂ laser were as low as 60 μJ. The laser cavity employed a multiple-pass off-axis path resonator in a ring configuration. CF₄ laser power at 615 cm^?1 and a 1-kHz repetition rate exceeded 300 μW.     

Amplifying medium characteristics in optimized 190 µm/195 µm DCN waveguide lasers

Extensive study of the CW, dischaxge-pumped, DCN laser operating on the (22⁰0-09¹0) 190 and 195 μm lines has been undertaken in order to develop a new source of radiation suitable for plasma diagnostics. The optimum values of the parameters of the discharge, the unsaturated gain, and the saturation intensity are given as a function of the tube diameter. Scaling laws predicting the maximum output power as a function of the tube dimensions and of the cavity loss are established. Such lasers compare favorably with optically pumped submillimeter lasers, since 250 mW are available from a 3 m long, 5 cm diameter waveguide DCN laser.     

Optically pumped submillimeter laser lines from CH2F2 and CD2Cl2 using a12C18O2 CW laser

Thirty-nine new submillimetre laser lines in CH₂F₂ and twelve in CD₂Cl₂ have been obtained in a Fabry-Perot FIR resonator by optically pumping with a CW¹²C¹⁸O₂ laser. The wavelength range obtained for CH₂F₂ is 126μm to 1091μm and for CD₂Cl₂ 212μm to 774μm. The wavelength measurements are accurate to within 5.10^?3. The relative polarisations of the pump laser and the FIR laser output were also determined. Tentative assignments of the IR and FIR transitions were made using existing microwave data.     

Optically-Pumped Far-Infrared Laser Lines in Hydrazine, Methanol, Heavy Water, and Ammonia: New Laser Lines and Frequency Measurements

A far-infrared laser cavity designed to favor short-wavelength laser lines was used to generate optically-pumped far-infrared laser radiation. New far-infrared laser lines were discovered in hydrazine, heavy water, ammonia, and several short-wavelength lines previously discovered in methanol were observed. Wavelength, frequency, and relative intensity measurements were performed on laser lines in the wavelength range 42.4 to 253.7 μm. Each far-infrared frequency measurement was obtained by mixing the far-infrared radiation with radiation from two reference CO₂ lasers and from a microwave synthesizer in a metal-insulator-metal diode. The pump laser was a high-Q Fabry Perot resonator oscillating on 275 grating-selected laser lines including regular, sequence, and hot band lines.     

自锁模Ti:Al2O3激光器自启动条件分析

本文分析了Ti:Al2O3激光器的自启动条件,讨论了不同腔参数对锁模产生的影响,计算了自锁模及自启动的调节范围,并在实验中实现了自启动锁模,计算结果与实验相吻合.     

连续的DCN波导激光器

本文介绍了连续DCN波导激光器。激光管由直径4.8厘米、长2.5米的石英管组成,其输出波长为195微米和190微米,最大输出功率为30毫瓦左右。同时给出实验研究结果以及输出功率与其他参数之间的关系。     

Submillimeter-wave dielectric measurements using an open-resonator

The open resonator method for dielectric measurements is developed in the submillimeter-wave region. This method, different from usual laser methods is based on the sweeping of resonator length. The conventional theory developed in the millimeter-wave region is improved so as to make measurements possible with resonable precision even in this frequency region and the design criterion of an optimum resonator at around 890 GHz (λ₀=337μm) is presented. Finally, the measurements are performed for several kinds of low loss material and it is confirmed that the present method becomes a useful one in the submillimeter-wave region.