NaCl Color Center Laser Research Articles

Preparation of NaCl color center laser crystals and perturbation effect of ions

NaCl:(F 2 +) AH-type color center laser crystals were prepared by the crystal growth, additional coloration, annealing, and by light aggregation at 290 and 77 K. The formation process of color center in NaCl crystals were investigated, the influence of doped cation and anion ions on the stability and optical properties of color centers is discussed in this paper.

High-Sensitivity Overtone Spectroscopy of Carbon Disulfide CS2

With opto-acoustic spectroscopy in a multipass cell, using a NaCl color center laser around 6500 cm−1, weak overtone transitions in the (3003) ← (0000) band of12C32S2could be detected. The analysis of the band, based on the extrapolation of molecular constants from the literature, revealed Fermi resonances between the levels of a Fermi polyad.

Interferometric measurement of wavelength dispersion on femtosecond laser cavities

Cavity Fourier-transformed cross correlation measures the wavelength dispersion from the cross-correlation signal taken on spontaneous emission emerging from a cavity under test. This method provides a universal and quick way to detect femtosecond group delay. However, test cavity-length fluctuations have been hindering its application to femtosecond laser cavities. We introduce a dual-interferometer scheme in which one of the interferometers is dedicated to detecting length change in the test cavity, thereby enabling the influence of fluctuations to be nullified. This method is demonstrated on a Ti:Al(2)O(3) laser as well as on a NaCl color-center laser.

Passive stabilization of a synchronously mode-locked NaCl color-center laser by coherent photon seeding

We use coherent photon seeding to passively stabilize a synchronously mode-locked NaCl color-center laser. This results in the generation of essentially transform-limited picosecond pulses with average power levels of as high as 1.3 W in the 1.5-1.7-microm range. In addition, the pulse energy fluctuations are reduced by as much as 1 order of magnitude.

Collision-induced pulse shortening in a mode-locked linear-cavity NaCl color-center laser with an InGaAs/InP multiple-quantum-well saturable absorber

We report collision-induced reduction of pulse widths in a linear-cavity passively mode-locked NaCl color-center laser. Colliding-pulse operation reduced the pulse widths from 800 to 430 fs. Pulses collided in the InGaAs/InP multiple-quantum-well saturable absorber if the round-trip time from the absorber to the output coupler was less than 1.3 ns, which implies carrier recombination times of that order. Measurements of the gain experienced by two successive pulses indicated partial saturation of the NaCl gain medium.

Bulk semiconductor saturable absorber for a NaCl color center laser

Using bulk InGaAsP as a saturable absorber we have passively mode locked a NaCl color center laser to produce transform-limited, pedestal-free pulses near 1.6 μm as short as 197 fs with up to 4.2 kW peak power. Our results simplify the saturable absorber material requirements and prove that excitons are not required for generating subpicosecond pulses. By comparing a dozen samples we find that a minimum band-edge absorbance of 40% is required to generate subpicosecond pulses, although details of the band edge are not critical. In addition, we find stable mode locking always occurs on the long-wavelength side of the laser gain peak.

Multiple quantum well passive mode locking of a NaCl color center laser

Using multiple quantum well (MQW) saturable absorbers, we passively mode locked a NaCl color center laser to produce transform-limited, pedestal-free pulses with τ as short as 275 fs and peak power as high as 3.7 kW. Because of exciton ionization with a 200±30 fs time constant, the MQW shows a fast absorption recovery that is comparable to our pulse widths. This fast component plays a major role in pulse shaping and may limit the pulse width. We also show that the wavelength for the short pulses can be tuned from 1.59 to 1.7 μm by choosing MQWs with different band gaps.

NaCl color center laser with birefringent tuning

A NaCl∶OH ring color center laser, tunable from 1.49–1.70 μm with a two plate birefringent filter has been realized, which yields 1.5 W output power at 6 W Nd-YAG input pump power. Calculations of the spectral net gain including the homogeneously broadened gain profile, the birefringent transmission characteristics, and the mirror reflectivities are presented and compared with the experimental results.

Pulsed, room-temperature operation of a tunable NaCl color-center laser

A room-temperature, pulsed, color-center laser using OH(-)-doped NaCl crystals is reported. Crystals were transversely pumped by a Q-switched Nd:YAG laser at 1.06microm and produced output energies of 8.6 mJ in 20-nsec pulses. The tuning range extended from 1.37 to 1.77 microm. During 40 h of operation (>10(6) pulses), a gradual power fading was observed. Laser action is tentatively ascribed to F(2)(+) centers.