ABSTRACT
We demonstrate a diode-pumped cw Raman laser in H(2) with photon-conversion efficiency of (66+/-8)%. Pumped by an injection-locked diode laser at 792 nm, the Stokes laser produces a peak output power of ~16mW at 1180 nm. Accompanying the high Stokes power are deviations from the existing theory, which are believed to be caused by the thermal-lensing effect of the Raman gas.
ABSTRACT
What is to the authors' knowledge the first experimental demonstration of a nonresonant cw Raman laser pumped by a tunable external-cavity diode laser (ECDL) is presented. The ECDL is phase-frequency locked to a high-finesse Raman laser cavity containing diatomic hydrogen (H(2)) by the Pound-Drever-Hall locking technique. The Stokes lasing threshold occurs at a pump power of 400 +/- 30 muW, and a maximum photon conversion efficiency of 12.0 +/- 1.3% is achieved at 1.6 mW of pump power. A 40-nm tuning range of the cw Stokes emission, 1174-1214 nm, is obtained by tuning of the wavelength of the ECDL pump source.
ABSTRACT
A complex spectral grating is accumulated by repeated application of a pair of low-power optical programming pulses to a short-term persistent inhomogeneously broadened transition in Tm:YAG at 4.5 K and then probed to investigate the buildup dynamics. The necessary frequency stability is obtained by locking a cw Ti:sapphire laser to a regenerating transient spectral hole in the same transition. Grating accumulation is demonstrated for both a periodic spectral grating, representing a true-time delay, and a complex spectral grating, permitting correlation-based pattern recognition. This work is a step toward demonstrating an optical coherent transient continuously programmed continuous processor.
ABSTRACT
A simple and accurate method for measuring the front facet modal reflectivity of a Fabry-Perot laser diode is presented. In this method, optical feedback from an external mirror of known reflectivity, R(ext), is used to alter the laser diode threshold current. The effect of the external mirror and front facet reflectivities on the threshold current then allows for a measurement of the front facet modal reflectivity of the laser diode and is theoretically and experimentally studied. This method was used to measure a facet reflectivity of R(2) = 0.0151(+0.0018/-0.0032) [R(2) = 0.00592(+0.00085/-0.00123)] for a commercially antireflection-coated facet of a laser diode with a center wavelength of 795 nm (935 nm). The results of the reflectivity measurements based on the threshold current as a function of the external mirror reflectivity are compared with the results of the reflectivity measurements based on modulation depth of the optical spectrum [IEEE J. Quantum Electron. QE-19, 493 (1983)].
ABSTRACT
A simple method for measuring the frequency-chirped response of lasers is presented. This method relates the deviation from the Lorentzian line shape of the transmission of a Fabry-Perot interferometer to the frequency chirp of the laser and allows a direct measurement of the frequency chirp. Two chirps produced by an external-cavity laser diode with an intracavity electro-optic crystal were measured. The first measurement was of a linear chirp of 800 MHz occurring in a time of 12.3 micros, and the second measurement was of eight repeated 800-MHz linear chirps each occurring in 337 micros. Agreement between the measured and the expected frequency-chirped response of the laser is shown.
ABSTRACT
Recent developments in high-finesse cavities now make broadly tunable, continuous-wave Raman lasers possible. The design and preliminary characterization of what is to the authors' knowledge the first continuous-wave Raman laser in H(2) are presented. The threshold is currently at 2 mW of pump, making diode laser pumping possible. The maximum photon conversion efficiency observed was 35% at 7.6 mW of pump power.
ABSTRACT
An off-axis spherical mirror is used to correct an astigmatic, non-Gaussian beam from a pulsed, frequency-doubled Nd:YAG laser. The beam is then spatially filtered by a series of two pinholes to make the beam near Gaussian.
ABSTRACT
The effects of temperature and pressure on the stability of a high-finesse interferometer are considered, and the design of a high-finesse interferometer that minimizes these effects is presented. The high-finesse interferometer has a free spectral range of 23,600 MHz, a finesse of greater than 30,000, and a measured stability of better than 7 MHz/h (0.3 mfringes/h).
ABSTRACT
A detailed plan for the construction and use of a nonconfocal cavity used as a high-finesse interferometer is presented. The interferometer has a free spectral range of l5 GHz, with a finesse of over 30,000.
ABSTRACT
Recent developments in tunable laser diodes now make it possible to do injection seeding of a quantum-limited Raman amplifier. We present data from an experiment in which a tunable laser diode in the visible was injected into a Raman amplifier with a coupling efficiency of 65% +/- 45%. This efficiency approaches the theoretical limit of 100% and is much larger than the 0.1-0.2% coupling efficiency reported in the literature for a comparable experiment when an infrared laser diode is used.
