Diode-pumped alkali laser
OwnerWilliam F. Krupkeinventor
Life of this patent
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Abstract
A new class of lasers is provided that can be pumped by conventional high-power, multi-mode, broadband 1-D and 2-D laser diode arrays, where the pumped laser gain medium comprises an atomic vapor of one the alkali elements (Li, Na, K, Rb or Cs), buffered with a mixture of rare-gas (He, Ar, Kr, Ne or Xe) and selected molecular gases. The alkali atom gain medium is pumped at a wavelength matching the wavelength of the 2S1/2-2P3/2 electric-dipole-allowed transition (the D2 transition). After kinetic relaxation of pump excitation to the excited 2P1/2 electronic level, laser emission takes place on the 2P1/2-2S1/2 transition (the D1 transition).
Claims25
An alkali vapor laser, comprising:
- an optical cavity resonant at a wavelength λ1, corresponding to a wavelength of the D1 transition of an alkali atomic vapor;
- a gain medium within said optical cavity, said gain medium comprising a mixture of at least one buffer gas and said alkali atomic vapor having said D1 transition wavelength matching said wavelength λ1 of said optical cavity, wherein said at least one buffer gas has the dual purpose of collisionally broadening said D2 transition and collisionally transferring pump excitation from the upper level of said D2 transition to the upper level of said D1 transition at a rate larger than the radiative decay rate of either of these two levels;
- and
- a pump laser emitting at wavelength λ2 with an emission spectral width within the range from 1-6 nm (FWHM), for optically pumping said laser gain medium at a wavelength of a D2 transition of said alkali vapor, including optical pumping in the Lorentzian spectral wings of said D2 transition, generating laser emission output at the wavelength λ1 of the D1 transition of the alkali vapor.
A method for converting spectrally broadband radiation from a pump semiconductor diode laser array into spectrally narrowband output laser radiation, comprising the steps of:
- pumping, with a pump laser having an emission spectral width within the range from 1-6 nm (FWHM), an alkali/buffer gas gain mixture at a wavelength λ2 of a pressure-broadened D2 transition of the alkali vapor, wherein said mixture is optically pumped well into the Lorentzian spectral wings of the D2 transition;
- and
- extracting spectrally narrowband laser radiation generated on the spectrally-homogeneous D1 transition of said alkali vapor, wherein said buffer gas collisionally induces a transfer of pump excitation from the upper level of said D2 transition to the upper level of said D1 transition at a rate larger than the radiative decay rate of either of these two levels, wherein said mixture comprises at least one buffer gas, wherein said at least one buffer gas has the dual purpose of collisionally broadening said D2 transition and collisionally transferring pump excitation from the upper level of said D2 transition to the upper level of said D1 transition at a rate larger than the radiative decay rate of either of these two levels.
A method for converting the substantially-divergent, multi-spatial-mode of semiconductor diode laser array pump radiation into a near diffraction-limited, near-single-spatial-mode, coherent laser radiation, comprising the steps of:
- depositing pump radiation at a wavelength λ2 matching a wavelength of a D2 transition of an alkali/buffer-gas gain mixture in a certain defined spatial volume (within the gain mixture cell placed in an optical cavity), including optical pumping in the Lorentzian spectral wings of said D2 transition, wherein said pump radiation is provided by a multi-spatial-mode semiconductor diode laser array comprising an emission spectral width within the range from 1-6 nm (FWHM);
- spatially over-lapping said volume with the fundamental mode of the alkali vapor laser cavity, designed to possess substantially higher losses for higher order spatial modes than for the fundamental mode;
- and
- extracting laser output power in the fundamental spatial mode of the laser cavity by providing the proper amount of transmission of radiation at an output wavelength λ1 matching a wavelength of a D1 transition of said alkali vapor, wherein said at least one buffer gas collisionally induces a transfer of pump excitation from the upper level of said D2 transition to the upper level of said D1 transition at a rate larger than the radiative decay rate of either of these two levels, wherein said mixture comprises at least one buffer gas, wherein said at least one buffer gas has the dual purpose of collisionally broadening said D2 transition and collisionally transferring pump excitation from the upper level of said D2 transition to the upper level of said D1 transition at a rate larger than the radiative decay rate of either of these two levels.
Dependencies are inferred from the claim text.