HF and DF laser action by a pulsed microwave discharge

A pulsed electrodeless microwave discharge withE-field enhancement by a tapered waveguide has been employed to produce HF and DF laser radiation from premixtutes of SF6+ H6and SF6+ D2. The 720 patm (690 patm) HF (DF) laser had an average multiline output power of 6 mW (1 mW) for an efficiency of 0.1 percent (0.02 percent) while operating at 1 kHz (450 Hz) pulse-repetition frequency (PRF). The HF (DF) laser was operated at reduced output power and efficiency up to 4.2 kHz (2.5 kHz) PRF. Reduced HF laser efficiency was obtained when C3H8was substituted for H2.     

Optoacoustic Laser Stark spectroscopy and FIR laser action on CH3Br using a waveguide CO2 laser

The optoacoustic spectrum of CH₃Br around 10 μm band lines of a tunable cw waveguide CO₂ laser is investigated. Several new infrared absorptions are observed and most of the correspond ing molecular transitions are assigned. Far infra red laser action is reported by pumping with the same CO₂ laser: pump offsets are given using the Transferred Lambs dip (TLD) technique. A new FIR laser emission is obtained and assigned. An optoacoustic Laser Stark spectroscopy technique is used to investigate off resonance infrared tran sitions.     

Fir laser stabilization using stark effect: Data on CH3Br and CH3Cl

Data on the influence of the Stark Effect on an optically pumped FIR laser with CH₃Cl or CH₃Br as active medium are given for various wavelengths. A very simple method for an effective FIR power stabilisation based on the Stark Effect is described. Its working is illustrated with the EPR signal of a 10% diluted DAG sphere.     

A continuously pulsed copper halide laser with a cable-capacitor Blumlein discharge circuit

Experimental characteristics of a continuously pulsed copper halide laser with a cable-capacitor Blumlein discharge circuit are reported. Quartz laser tubes 1 m in length and 1.5 and 2.5 cm in diameter were employed to study the effects of the electrical circuit, lasant, and buffer gas on laser performance. Measured properties of the Blumlein circuit are compared with an analytic solution for an idealized circuit. Both CuCl and CuBr with neon and helium buffer gas were studied. A maximum average power of 12.5 W was obtained with a 1.5 nF capacitor charged to 8 kV and discharged at 31 kHz with CuCl and neon buffer gas at 0.7 kPa in a 2.5-cm-diam tube. A maximum efficiency of 0.72 percent was obtained at 9 W average power. Measurements of the radial distribution of the power in the laser beam and the variation of laser power at 510.6 and 578.2 nm with halide vapor density are also reported. Double and continuously pulsed laser characteristics are compared, and the role of copper metastable level atoms in limiting the laser pulse energy density is discussed.     

电引发脉冲氧碘化学激光器的增益

本文对脉冲氧碘化学激光器的增益性能进行了理论估算。碘原子由CH_3I电离产生。研究了各种压力条件下成份比和CH_3I离解度对增益系数的影响。     

New FIR laser lines from optically pumped C2H3F,C2H3Cl,C2H3Br,C2H3CN,C2H5F,CH2CF2, HCOOH and CH3Br

Twenty-seven new cw far infrared laser lines with wavelengths between 137 and 988Μm have been observed from optically pumping C₂H₃F, C₂H₃Cl, C₂H₃Br, C₂H₅F, C₂H₃CN, CH₂CF₂, HCOOH and CH₃Br with a CO₂ laser. The wavelengths of these FIR laser lines were determined together with their optimum pressures and relative intensities.     

Planarization of gold and aluminum thin films using a pulsed laser

Micrometer-thick gold and aluminum films have been planarized by momentarily melting them with optical pulses from a dye laser. Submicrosecond pulses were used in order to minimize the temperature rise in the substrate, reduce the energy required for melting, and prevent undesirable metallurgical reactions. Planarization of two-level gold metallization structures insulated by SiO2(including interlevel vias) has been achieved. Aluminum metallization on integrated circuits (IC's) has also been planarized. The use of a thin (<200 Å) silicon overcoating greatly aids the aluminum planarization process by passivating the aluminum and increasing its initial optical absorbance.     

Cavity operation of a pulsed C13H3F laser

Cavity operation of an optically pumped, pulsed, C¹³H₃F far-infrared laser is described. The use of a Fabry-Perot output coupler has resulted in selectable line emission at 1222, 1207, 1006, 388 and 412 μm with power levels in the 1–20 kW range. In addition, single mode operation on the longer wavelength lines has been achieved. Experimental evidence is also presented for a collisionally coupled two-photon absorption process which is responsible for the observed short wavelength emission.     

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.     

Fiber optic microwave links using balanced laser harmonicgeneration, and balanced/image cancellation laser mixing

Three fiber-optic link configurations for use in microwave transmission are proposed. Two laser diodes are used to generate balanced harmonics, and the optical power from each diode is combined and detected by photodiodes. The fundamental and odd harmonics are suppressed and even harmonics added. The balanced and image cancellation laser mixing, which utilizes a combination of microwave components and optical devices, can suppress the local and image frequencies, respectively. These configurations are experimentally investigated at microwave frequencies, and frequency suppression is successfully demonstrated     

Highly conductive buried n+ layers in lnp:fe created by MeV energy Si,S, and Si/S implantation for application to microwave devices

To obtain highly conductive buried layers in InP:Fe, MeV energy Si, S, and Si/ Simplantations are performed at 200°C. The silicon and sulfer implants gave 85 and 100 percent activation, respectively, for a fluence of 8 × 10¹⁴ cm⁻². The Si/S co-implantation also gave almost 100 percent donor activation for a fluence of 8 × 10¹⁴ cm⁻² of each species. An improved silicon donor activation is observed in the Si/S co-implanted material compared to the material implanted with silicon alone. The peak carrier concentration achieved for the Si/S co-implant is 2 × 10¹⁹ cm³. The lattice damage on the surface side of the profile is effectively removed after rapid thermal annealing. Multiple-energy silicon and sulfur implantations are performed to obtain thick and buried n⁺ layers needed for microwave devices and also hyper-abrupt profiles needed for varactor diodes.     

Observation of turn-on action in a gate-triggered thyristor using a new microwave technique

The turn-on action by the p-base and n-emitter gates in a thyristor was studied by a new microwave technique. The initial conducting area, the lateral distribution of gate current flowing through the junction, and the time variation of excess carrier density injected into the n-base by the gate current were determined by measuring the reflection of microwave energy, vertically incident upon a small area (0.2 × 0.2 mm²) of the n-emitter layer. The new microwave technique has proved to be useful in designing new gate structures and in studying the operation of new devices.     

Fiber-optic microwave transmission using harmonic laser mixing,optoelectronic mixing, and optically pumped mixing

Three fiber-optical link configurations are proposed for use in microwave and millimeter-wave signal transmission. Harmonic laser mixing, optoelectronic mixing and optically pumped mixing are successfully utilized to achieve high carrier frequencies in fiber-optic links. The performance of harmonic laser diode mixers is experimentally investigated in the X-band. The p-i-n photodiode is used as an optoelectronic microwave mixer and an optically pumped microwave mixer, and the microwave characteristics of these mixers are demonstrated. These three fiber-optic link configurations show promise in transmitting microwave and millimeter-wave frequencies     

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.     

Threshold of inelastic strain formation in Si and GaAs surface layers under multiple pulsed laser irradiation

For the first time, a contactless local photoacoustic technique based on the spectroscopy of laser beam deviation was used to estimate maximal values of elastic shear strains ?₀ in micrometer-sized surface regions of Si and GaAs; the values obtained fall in the range of 10^?50<10^?4. The development of irreversible inelastic processes in the surface layers of semiconductors subjected to a series of focused laser pulses under photoinduced quasistatic strains ?>?₀ is demonstrated. Studying the diffuse and Raman scattering of light near the thresholds ?₀ suggests that the early stage of the inelastic cyclic strain photoinduced in the surface layers is accompanied by the generation and spatial redistribution of point rather than extended defects (e.g., dislocations). A number of threshold values, such as the photoinduced increase in the temperature and the mean shear stresses that appear in the surface layers of Si and GaAs samples exposed to local submicrosecond radiation, are estimated. The physical nature of the low-threshold effects is discussed.     

All-optical generation of microwave and Millimeter wave using a two-frequency Bragg grating-based Brillouin fiber laser

A novel all-optical technique for microwave/millimeter-wave generation using two-frequency fiber Bragg grating (FBG)-based Brillouin fiber laser is presented. The mechanism for the microwave and millimeter-wave generation is theoretically analyzed. An approximately 33-GHz millimeter wave can be achieved through mixing the pump wave with the third Stokes' wave. In the experiment, an 11-GHz microwave signal is attained. The microwave frequency can be tuned by varying temperature of the fiber Fabry-Pe/spl acute/rot cavity of the Brillouin fiber laser. A more than 100-MHz tuning range around a frequency of 11 GHz is experimentally achieved.     

The inductance and resistance of the laser discharge in a pulsedgas laser

Theoretical consideration of the discharge of a laser channel takes place in this work. This leads to formulas for the resistance and inductance. The resistance depends on the total charge in the discharge volume while the inductance depends on the dimensions of the discharge volume. Generally, the inductance increases as electrode length and discharge thickness decreases and more so as these become equal. On the other hand the inductance increases as interelectrode distance increases. However, discharge dimensions depend on the drift velocity of the flowing charges creating centripetal Lorenztian forces which constrict the volume of the laser channel. Consequently, the microscopic parameters of the plasma, total charge and drift velocity are responsible for the electrical macroscopical characteristics' resistance and inductance respectively. Nevertheless, these microscopic parameters are formed through the external driving circuit and especially through its capacitance which strongly influences the discharge of the laser channel. Particularly, the values of the capacitances form the total charge, while the coupling of the capacitances in the circuit forms the drift velocity. These were inferred dealing with the two most common circuits used in pulsed gas lasers, namely the “doubling circuit” and the “charge transfer circuit” for all possible combinations of capacitance allocation     

三色氦镉激光器阴极放电孔径与瞬间跳火的关系

笛形空心阴极三色氦镉激光器在彩色图像处理、假彩色、光谱仪器的波长标定等方面,具有广泛的应用前景.但由于激光器工作时存在瞬间跳火问题,使其不能获得长期稳定的功率输出.本文对三色氦镉激光器产生瞬间跳火的原因进行了分析,讨论了两种不同阴极放电孔对放电的影响,从而获得解决这一问题的方法,并在实验中得到验证.1.在一般空心阴极灯放电条件下,当充入的气体为氦,阴极孔直径为4～10mm时,能产生空心阴极放电效应的气压范围为15～25Torr,但在实际制成的笛形空心阴极三色氦镉激光管中,在气压