Showing papers by "Leo W. Hollberg published in 1995"
TL;DR: In this article, a V-type atomic configuration of Rb vapor was used to demonstrate the effect of the atomic interference on laser oscillation without population inversion in a V configuration.
Abstract: Laser oscillation without population inversion is demonstrated experimentally in a V-type atomic configuration within the ${D}_{1}\mathrm{and}{D}_{2}$ lines of Rb vapor. It is shown that the effect is due to the atomic interference. The experimental results, as first predicted by careful theoretical analysis, are in a good agreement with detailed calculations.
421 citations
TL;DR: In this paper, the authors used an 800 nm diode laser and a diode-pumped 1064 nm Nd:YAG laser to produce tunable light near 3.2 µm.
Abstract: Spectroscopic detection of the methane in natural air using an 800 nm diode laser and a diode-pumped 1064 nm Nd:YAG laser to produce tunable light near 3.2 µm is reported. The lasers were pump sources for ring-cavity-enhanced tunable difference-frequency mixing in AgGaS2. IR frequency tuning between 3076 and 3183 cm−1 was performed by crystal rotation and tuning of the extended-cavity diode laser. Feedback stabilization of the IR power reduced intensity noise below the detector noise level. Direct absorption and wavelength-modulation (2f) spectroscopy of the methane in natural air at 10.7 kPa (80 torr) were performed in a 1 m single-pass cell with 1 µW probe power. Methane has also been detected using a 3.2 µm confocal build-up cavity in conjunction with an intracavity absorption cell. The best methane detection limit observed was 12 ppb m (Hz.)−1/2.
36 citations
TL;DR: In this paper, an AgGaS2 was used to generate more than 2 μW of cw mid-infrared radiation near 3.2 μm by difference-frequency mixing of the outputs of an extended-cavity diode laser near 795 nm (pump wave) and a compact diode-pumped Nd:YAG laser at 1064 nm (signal wave).
Abstract: AgGaS2 has been used to generate more than 2 μW of cw mid-infrared radiation near 3.2 μm by difference-frequency mixing of the outputs of an extended-cavity diode laser near 795 nm (pump wave) an a compact diode-pumped Nd:YAG laser at 1064 nm (signal wave). An external ring enhancement cavity was used to build up the signal power inside the nonlinear crystal by as much as 14.5 times. The novel mid-infrared source incorporating a single diode laser could be angle-tuned from 3.155 to 3.423 μm (from 3170 to 2921 cm−1). This system was used to detect the Doppler-broadened fundamental ν3-asymmetric stretch vibration of methane (CH4) by both direct and wavelength-modulation absorption spectroscopy.
32 citations
Proceedings Article•
22 May 1995
TL;DR: Laser oscillation without population inversion is demonstrated experimentally in a V-type atomic configuration within the lines of Rb vapor and it is shown that the effect is due to the atomic interference.
Abstract: Laser oscillation without population inversion is demonstrated experimentally in a V-type atomic configuration within the ${D}_{1}\mathrm{and}{D}_{2}$ lines of Rb vapor. It is shown that the effect is due to the atomic interference. The experimental results, as first predicted by careful theoretical analysis, are in a good agreement with detailed calculations.
23 citations
TL;DR: In this paper, an optical polarization heterodyne technique was used to measure the frequencies of two OCS lines, one near 5.3 μm and the other near 5.9 μm.
12 citations
26 Apr 1995
TL;DR: In this paper, the authors measured the increase in low-frequency amplitude noise on several extended cavity diode lasers when frequency of phase lock servos were applied using the injection current as the feedback channel, and the AM noise increase inside the FM servo bandwidth is approximately that expected from the suppression of frequency noise uncorrelated with the inherent amplitude noise of the laser.
Abstract: The increase low-frequency amplitude noise on several extended cavity diode lasers was measured when frequency of phase lock servos were applied using the injection current as the feedback channel. The AM noise increase inside the FM servo bandwidth is approximately that expected from the suppression of frequency noise uncorrelated with the inherent amplitude noise of the laser.
6 citations
01 Jan 1995
TL;DR: In this article, the authors present a simple, Rb-stabilized microwave oscillator with a single-mode diode laser DL1 (drive laser) passing through a Rb cell and then detected on a fast photodiode (DL2) that can be spectrally broadened by adding noise to the injection current.
Abstract: Gain and oscillations are observed in a 3-leve1, A configuration when Rb atoms arc driven with a strong, coherent, laser field and a broadband repumping laser. The system automatically generates an output beam that has a beatnote a! the frequency of the ground state hyperfie splitting (6.8 GHz). Gain is due to both population and coherence effects in a Raman configuration. The experimental system is extremely simple and shows promise of providing a compact, Rb-stabilized microwave oscillator. Large Raman gain signals are observed in the very simple experimental setup diagrammed in Fig. 1. The beam from a single-mode diode laser DL1 (drive laser) is passed through a Rb cell and is then detected on a fast photodiode. DL2 is a solitary diode-laser that can be spectrally broadened by adding noise to the injection current. These two input beams propagate through the cell (either in the same or opposite directions) at a small angle that allows separation of the beams and avoids feedback. Rb POLARIZER AYPLIIIER I DL1 f : / I electronic Fig. 1 Experimental setup consists of two diode laser beams, a Rb cell, a fast photodetector, and a microwave spectrum analyzer used to display the signal. The dotted line indicates the electronic feedback path that is used in some of the experiments. Raman scattering of the drive laser in the Rb vapor generates a beam that is collinear with the drive but is frequency-shifted by the ground state hyperfine splitting (3.0 and 6.8 GHz for Rb" and Rb"). The fast photodiode simply detects the beatnote between the drive laser and the Raman shifted beam. The function of the repumping laser @L2) is to return the population to the initial ground-state hyperfine level, thus controlling the optical pumping effects of the drive laser. The tuning of the broadband repumping laser is not critical; any Proc. Fifth Symp. On Frequency Standards and Meterology (1995). TN-264
5 citations
01 Jan 1995
3 citations
31 May 1995
TL;DR: In this article, a two-stage optical cooling of calcium may be feasible; this should improve the accuracy of the 657 nm optical wavelength/frequency reference, and progress in developing an all diode-laser system for cooling, trapping and precision spectroscopy of calcium is discussed.
Abstract: As they apply to frequency standards and precision spectroscopy the characteristics and technology of tunable diode lasers are briefly reviewed. It is now possible to use nonlinear optical techniques and high quality diode lasers to extend the useful wavelength coverage of semiconductor lasers into the UV, the IR and even millimeter-wave spectral regions. Progress in developing an all diode-laser system for cooling, trapping and precision spectroscopy of calcium is discussed. New measurements indicated that two-stage optical cooling of calcium may be feasible; this should improve the accuracy of the 657 nm optical wavelength/frequency reference.
2 citations
30 Oct 1995
TL;DR: In this paper, a diode-laser-based technique for sensitive atmospheric trace detection gases such as CH/sub 4/, CO, N/sub 2/O, and NO was developed.
Abstract: This work was done to develop a diode-laser-based technique for sensitive atmospheric trace detection gases such as CH/sub 4/, CO, N/sub 2/O, and NO. Spectroscopic detection of methane in the fundamental, and overtone stretch vibration bands using tunable infrared lasers has been reported. The /spl nu//sub 3/ band of methane near 3.2 /spl mu/m includes its strongest known molecular transition and therefore is better suited for sensitive detection. The band is accessible by either conventional spectroscopy or with Ar/sup +/-dye laser difference-frequency generation, the carbon monoxide overtone laser, the helium-neon laser near 3.39 /spl mu/m, lead-salt diode lasers, and color-center lasers. However, each one of these mid-infrared laser sources suffers from its own specific practical drawbacks such as large physical size, lack of portability, high cost, high power consumption, poor tunability, or the need for cryogenic cooling. In the work, detection of the methane in natural air (1.8 ppmv) was performed using diode-laser-pumped cavity-enhanced CW tunable difference-frequency generation (DFG) near 3.2 /spl mu/m.
30 Oct 1995
TL;DR: In this article, a wide variety of new laser applications would be feasible if we had tunable, single-frequency laser sources that were compact, lightweight and operated with low power consumption.
Abstract: A wide variety of new laser applications would be feasible if we had tunable, single-frequency laser sources that were compact, lightweight and operated with low power consumption. Some of these applications include: atmospheric and process monitoring, atomic and molecular spectroscopy, ultrasensitive detection and analytic applications, lidar and ranging, and new optical frequency/length references. Semiconductor diode lasers can now meet these challenges in many cases, particularly for laboratory experiments. Extension of this technology to higher powers, extended wavelength coverage, and transportable instrumentation is on the near term horizon. For some time now it has been possible to construct single-frequency tunable diode laser systems that operate at many wavelengths in the red and near IR spectral region. Even commercial tunable diode laser systems are now readily available at most of the wavelengths accessible with commercial semiconductor lasers chips.