A. Mooradian

Single-frequency microchip Nd lasers.

Optically pumped, single-frequency, Nd-doped, solid-state lasers have been constructed using flat-flat cavities, which were diced from large dielectrically coated wafers of various crystals. For example, a Nd:YAG laser with a cavity length of 730 microm has operated at room temperature in a single longitudinal mode from a threshold of less than 1 mW to greater than 40 times the threshold. Theslope efficiency was greater than 30%. Heterodyne measurements showed an instrument-limited linewidth of 5 kHz. The microchip lasers demonstrate ways to reduce greatly the cost and complexity offabricating small lasers and electro-optic devices.

Frequency-modulated Nd:YAG microchip lasers

Tunable, single-frequency, Nd:YAG microchip lasers have been piezoelectrically frequency modulated over several hundred megahertz at rates from dc to 25 MHz.

Gain-switched pulsed operation of microchip lasers

Microchip lasers have produced single-frequency, gain-switched pulses with a FWHM as short as 760 psec for Nd:YAG (Nd(x)Y(3-x)Al(5)O(12)) and 80 psec for LiNdP(4)O(12) (LNP).

High-power, continuous-wave, Nd:YAG microchip laser array

A transversely extended, flat-flat monolithic Nd:YAG laser cavity was pumped by a two-dimensional laser-diode array to form an array of cw microchip laser emitters with total output power of 9.8 W for an incident pump power of 38.5 W. The ensemble optical efficiency was 25.5%, the slope efficiency was 32.5%, and the beams were shown to have excellent spatial mode quality and parallelism.

High-resolution double-resonance spectroscopy of 2ν 3 ← ν 3 transitions in SF 6

We assign the 2v(3) ? v(3) absorption transitions seen in a double-resonance pump-probe experiment. We compare the observed frequencies with those derived by calculating the 2v(3) rovibrational energy levels, using spectroscopic constants resulting from a 3v(3) analysis. Some features in the multiple-photon v(3) absorption spectrum of SF(6) can be attributed to two-photon transitions to 2v(3).

Mode-locked operation of Co:MgF(2) and Ni:MgF(2) lasers.

Tunable, mode-locked operation of cw Co:MgF(2) and Ni:MgF(2) lasers has been demonstrated for the first reported time, and autocorrelation measurements of the pulse widths have been made. The Co:MgF(2) system has generated stable pulses over wavelengths from 1.65 to 2.01 microm and has produced pulses as short as 34 psec. The Ni:MgF(2) laser has operated over the 1.61-1.73-microm range, with pulses as short as 23 psec.

Spectral linewidth of a free-running continuous-wave single-frequency external-cavity quantum-well InGaAs / AlGaAs diode laser.

The linewidth of a room-temperature free-running 940-nm cw single-frequency 1-mm-long quantum-well InGaAs/AlGaAs diode laser in a 10-cm-long external cavity has been measured as a function of the output power by the heterodyne technique. The power-dependent component of the observed Lorentzian linewidth displays a linewidth–power product of 28 ± 4 kHz mW, which is 2 orders of magnitude larger than that predicted from the spontaneous emission model. The shot-noise model of Welford and Mooradian [Appl. Phys. Lett. 40, 560 (1982)] for the power-independent linewidth has been extended to account for the observed power-dependent linewidth.

Progress in Laser Sources for Remote Sensing

Substantial progress in both active and passive remote sensing using laser sources has been demonstrated in the past several years. At present, the development of laser remote sensing is limited by the availability of adequate tunable laser sources. We describe here the results of recent progress in the development of various tunable laser sources which will be of use for both active and passive laser remote sensing. Included among these sources are transition-metal ion-doped solid-state lasers, semiconductor diode lasers in external cavities, miniature CO2 TEA lasers, and frequency conversion in infrared nonlinear materials.

High Average Power Mode-Locked Co: MgF2 Laser

The use of Co:MgF2 as a laser material was first demonstrated in the early years of laser development [1]. More recently, vibronic lasers such as Co:MgF2 have proven to be versatile, broadly tunable, cw and pulsed sources of infrared radiation [2,3]. We report here the first tunable, cw mode-locked operation of this laser.