Abstract There is disclosed an optically pumped solid-state laser with a dielectric crystal or glass host for the active medium. The pulse frequency, phase, height and width of relaxation oscillation pulsing are controlled by externally detecting the phase difference between a stable periodic perturbation of the pump light and the output pulse, then externally feeding back a signal to restore the laser output pulse phase to a fixed relationship to the phase of the perturbation. The perturbation can be provided by a small luminescent diode. Alternatively, the resonator loss can be modulated at the relaxation oscillation frequency by an acoustic cell in which the perturbations are scaled down by two or three orders of magnitude from those in an acoustic Q-switch. Moreover, relaxation oscillation pulsing of a single laser mode and frequency can be stimulated by employing the foregoing control technique and concurrently preventing spatial hole burning, specifically by varying the optical spacing between the ends of the laser rod and respective ones of the resonator mirrors simultaneously in inverse relationship.
A laser comprising a solid-state active medium, means for optically pumping said active medium to produce a population inversion suitable for the stimulated emission of radiation, means for resonating said radiation, said medium and said pumping and resonating means together yielding a selected frequency of relaxation pulsing for said laser and including a source of a periodic perturbation at said selected frequency, and means for stabilizing the phase of said relaxation oscillation pulsing to the phase of said perturbation comprising an external feedback circuit including means for detecting a phase difference of said pulsing and said perturbation, and means responsive to said detecting means for changing the total optical pumping power to reduce said phase difference.
Claim 2
Dependent Claim
116 words
A laser comprising a solid-state active medium, means for optically pumping said active medium to produce a population inversion suitable for the stimulated emission of radiation, means for resonating said radiation, said medium and said pumping and resonating means together yielding a selected frequency of relaxation pulsing for said laser and including a source of a periodic perturbation at said selected frequency, and means for stabilizing the phase of said relaxation oscillation pulsing to the phase of said perturbation comprising an external feedback circuit including means for detecting a phase difference of said pulsing and said perturbation, and means responsive to said detecting means for changing the total optical pumping power to reduce said phase difference.
Claim 3
Dependent Claim
37 words
A laser according to claim 1 in which the source of the periodic perturbation includes auxiliary optical pumping means disposed to illuminate the active medium and means for driving said auxiliary pumping means at the selected frequency.
Claim 4
Dependent Claim
52 words
A laser according to claim 2 in which the solid-state active medium comprises a dielectric host and active atoms therein, and the means for changing the total optical pumping power comprises a variable power supply coupled to the first-said optical pumping means and varied by the means for detecting the phase difference.
Claim 5
Dependent Claim
18 words
A laser according to claim 3 in which the auxiliary optical pumping means comprises a semiconductor luminescent diode.
Claim 6
Dependent Claim
40 words
A laser according to claim 3 in which the auxiliary optical pumping means provides at the active medium an optical perturbation, the peak intensity of which is two to three orders of magnitude smaller than the total optical pumping power.
Claim 7
Dependent Claim
54 words
A laser according to claim 1 in which the resonating Means includes means for varying the optical position of said active medium within said resonating means at a rate to prevent spatial hole burning in said active medium, whereby said relaxation oscillation pulsing occurs in a single mode and frequency of the stimulated radiation.