High power laser with tuning and line narrowing capability
AssigneeGeneral Electric Company
InventorYung S. Liu
Life of this patent
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Abstract
The cavity of a high power laser is selectively tuned to oscillate in a relatively narrow spectral region by placing inside the cavity a birefringent KD*P filter at the Brewster angle. The degree of phase retardation introduced by the filter is controlled by applying an amplitude-variable voltage across the filter or rotating the filter about its .beta. axis. The laser may thus be line-narrowed and tuned, and may be used to generate two coherent signals at different wavelengths without need for an additional resonant cavity.
Claims21
A high power, Q-switched, tunable laser comprising:
- an optically-resonant cavity having reflector means at either end thereof;
- an active medium comprising neodymium-doped glass disposed within said cavity so as to emit optical energy in a direction normal to the reflecting surface of each of said reflector means;
- an electro-optical phase-shifting cell disposed within the cavity in the path of the emitted optical energy;
- and
- a birefringent filter situated within the cavity and having at least one face substantially at the Brewster angle with respect to the path of optical energy emitted from the active medium, said birefringent filter having refractive indices along mutually perpendicular .alpha., .beta. and .gamma. directions and being cut with its .beta. axis normal to said one face and being rotatable about said .beta. axis.
A high power, Q-switched, tunable laser comprising:
- an optically-resonant cavity having reflector means at either end thereof;
- an active medium comprising neodymium-doped glass disposed within said cavity so as to emit optical energy in a direction normal to the reflecting surface of each of said reflector means;
- an electro-optical phase-shifting cell disposed within the cavity in the path of the emitted optical energy;
- a birefringent filter situated within the cavity and having at least one face substantially at the Brewster angle with respect to the path of optical energy emitted from the active medium, said birefringent filter having refractive indices along mutually perpendicular .alpha., .beta. and .gamma. directions and being cut with its .beta. axis normal to its face and being rotatable about said .beta. axis;
- and
- a non-linear crystal situated in the path of optical energy emitted from said cavity, the angular position of said filter being selected such that two discrete line wavelengths are emitted from said cavity and optically mixed in said nonlinear crystal to produce a beat frequency wavelength.
A high power, tunable laser comprising:
- an optically-resonant cavity having reflector means at either end thereof;
- an active medium disposed within said cavity so as to emit optical energy in a direction normal to the reflecting surface of each of said reflector means;
- a birefringent electro-optic filter situated within the cavity and having at least one face substantially at the Brewster angle with respect to the path of optical energy emitted from the active medium, said birefringent filter having refractive indices along mutually perpendicular .alpha., .beta. and .gamma. directions and being cut with its .beta. axis normal to said one face;
- and
- means coupling a controllable DC voltage across opposite end faces of said filter.
A high power, tunable laser comprising:
- an optically-resonant cavity having reflector means at either end thereof;
- an active medium disposed within said cavity so as to emit optical energy in a direction normal to the reflecting surface of each of said reflector means;
- a birefringent electro-optic filter situated within the cavity and having at least one face substantially at the Brewster angle with respect to the path of optical energy emitted from the active medium;
- means coupling a controllable D.C. voltage across oppisite end faces of said filter;
- and
- a nonlinear crystal situated in the path of optical energy emitted from said cavity, the angular position of said filter being selected such that two discrete line wavelengths are emitted from said cavity and optically mixed in said nonlinear crystal to produce a beat frequency wavelength.
The method of simultaneously generating two discrete wavelengths from a single laser having a single optically-resonant cavity therein, comprising the steps of:
- stimulating transitions from the excited state of an active medium within said cavity to a lower energy state;
- line-narrowing the spectrum of oscillations within said resonant cavity;
- and
- retarding the phase of optical oscillations within said cavity to a value such that two discrete wavelength lines therein are produced.
Dependencies are inferred from the claim text.