W. T. Whitney

Sustained discharge excitation of HgCl and HgBr B2Σ+1/2→X2Σ+1/2 lasers

This letter reports e‐beam‐sustained discharge excitation of HgCl and HgBr lasers operating on the green and blue‐green B2Σ+1/2→X2Σ+1/2 bands in 2‐atm mixtures of Ar/Hg/Cl2 and Ar/Hg/BrCCl3. The excitation channel appears to be through the reaction of Hg(3P) metastable atoms with the halogen‐containing species.

Operation of a 15‐atm electron‐beam‐controlled CO2 laser

We describe the operation of a 15‐atm electron‐beam‐controlled CO2 laser. Stable glow discharges have been sustained in the high‐pressure He:CO2:N2 mixtures for 0.5 μsec using an electron‐beam current of ≲ 1.5 A/cm2. A small‐signal gain ∼ 0.052 cm−1 has been measured in a 70%(He):25%(CO2):5%(N2) mixture for an energy input to the gas ∼ 115 J/l atm. We have obtained a laser output energy of 1.2 J from a volume of 22 cm3 for an over‐all efficiency of 2.5%.

Interferometric tuning of a 15−atm CO2 laser

Efficient controlled frequency narrowing and tuning of a high−power 15−atm electron−beam−controlled CO2 laser has been achieved using a Fabry−Perot etalon as a dispersive element in the laser resonator. Tuning has been accomplished over the free spectral range of the etalon (∼2.3 cm−1) giving a laser linewidth of <0.2 cm−1 for an output pulse energy ∼100 mJ in a spot size ∼1 mm2. The laser pulse length is ∼40 nsec for a peak power ∼5 MW.

Wide-band interferometric tuning of a multiatmosphere CO2 laser☆

Abstract We describe the operating characteristics of a compact, frequency tunable, electron-beam-controlled, 15 atmosphere CO 2 laser. Two intracavity Fabry-Perot etalons have been used to obtain laser line narrowing and continuous tuning within the 10.4 μm and 9.4μm bands of the CO 2 gain spectrum. The laser output consists of a 100 nsec pulse (fwhm) with energy up to 100 mJ. The overall laser tuning range is 70 cm -1 and we have measured a laser linewidth of 0.03 cm -1 .

High-average-power operation of a Q-switched diode-pumped holmium laser

We have investigated high-peak- and high-average-power operation of diode-pumped, thulium-sensitized, holmium 2.1-microm lasers. Free-running laser powers of 14 W at 29 Hz have been demonstrated with 2.6% electrical efficiency. Q-switched operation produced average powers in excess of 11 W in a burst of short pulses. Preliminary optical parametric oscillator frequency conversion of the holmium laser to 4 microm is also reported.

Forced‐convective‐flow carbon monoxide laser

Forced convective flow has been applied to a CO laser, resulting in an order‐of‐magnitude enhancement of the output power density over what can be achieved from the same laser under diffusion‐dominated operation. A 1‐m‐long 2.5‐cm‐diam‐bore laser has produced 400 W of cw emission at 20% electrical efficiency.

Stimulated Brillouin scattering and phase conjugation of hydrogen fluoride laser radiation

Stimulated Brillouin scattering (SBS) of hydrogen fluoride laser radiation has been demonstrated for the first reported time. A flash-lamp-pumped pulsed chemical laser, operating single-line at 2.91 microm, was used to generate backward-stimulated Brillouin scattering in high-pressure xenon gas with power reflectivities of ~50%. Intentional aberration and subsequent restoration of a high-spatial-quality beam provided evidence of phase conjugation by the SBS process.

Continuously tunable multiatmosphere N2O and CS2 lasers

We describe the operating characteristics of pulsed multiatmosphere electron‐beam‐controlled He:CO:N2O and He:CO:CS2 lasers. Continuous interferometric tuning of these lasers has been achieved giving a tunable linewidth of <0.1 cm−1 for a laser pulse energy of 115 mJ from N2O and 45 mJ from CS2.

Stimulated Brillouin scattering and loop threshold reduction with a 2.1-μm Cr,Tm,Ho:YAG laser

We have investigated stimulated Brillouin scattering (SBS) in carbon disulfide, using a frequency-narrowed Cr,Tm,Ho:YAG laser operating at 2.12 μm. Threshold reduction with a novel loop geometry is also demonstrated. A model for the loop-SBS scheme is developed and compared with experimental results. Backscatter power, energy, and conjugate-fidelity data are presented.

Metal C ring window seal

We have constructed an optical cell with CaF2 windows which are sealed with metal C rings. We have demonstrated vacuum leak rates for He of less than ∼10−9 std atm cc/s between 20 and 110 °C, as well as pressure cycling between ∼10−4 Pa and ∼5 MPa. This seal is useful where outgassing or permeability of elastomeric O rings would present problems.