ABSTRACT
Using a technique similar to chirped pulse compression, we have compressed the 50-mW cw output of a diode laser into pulses of greater than 500-mW peak power and less than 400-ps duration. By applying a small current modulation to the diode, we induced a small wavelength modulation in the vicinity of the 6s(1/2)-to-6p(3/2) cesium resonance transition at 852 nm. Group-velocity dispersion on propagation through a cesium vapor cell then led to pulse compression. We developed a simple model to make predictions of output pulse shapes by using different modulation waveforms.
ABSTRACT
To achieve quantum-noise-limited performance, background-limited laser receivers require narrow-band optical filters. We measured and modeled the ultranarrow-band transmission spectrum of a Cs Faraday filter at 852 nm. The transmission spectrum consisted of passbands on either side of the 6 (2)S((1/2))-6 (2)P(3/2) hyperfine doublet lines, making a total of four. The passbands may be simple peaks or highly modulated, depending on the operating parameters. We observed peaked passbands of near-unity transmission with a 0.6-GHz bandwidth and modulated bands with features as sharp as 100 MHz. Excellent agreement with our calculations at 852 nm allows us to predict confidently a 0.7-GHz transmission band for Cs at 455 nm.
ABSTRACT
An experimental demonstration of a long-range, noncoherent laser Doppler velocimeter (LDV) is presented. The LDV detects incoming Doppler-shifted signal photons by using the sharp spectral absorption features in atomic or molecular vapors. The edge of the absorption feature is used to convert changes in frequency to large changes in transmission. Preliminary measurements of wind velocity using seeded aerosols showed that the LDV results agreed with mechanical anemometer measurements to within the accuracy of the LDV measurements. With optimization the LDV will provide accurate range-resolved and vibration-tolerant wind-speed measurements at large distances.
ABSTRACT
We report operation of the first high average power Nd:glass active-mirror amplifier, a scalable laser device that may be used to configure solid-state laser systems with high average power output into the kilowatt regime. An extractable average power of over 120 W was achieved at the device laser material fracture limit and at a repetition rate of 5 Hz.
