Transverse-excitation laser with preionization
First Claim
1. A transverse excitation laser comprisingmeans defining an optical axis along which the laser light propagates,cathode and anode electrode means positioned in opposed relationship along said optical axis for establishing therealong a transverse electric field,insulating side wall members forming with said cathode and anode means a waveguide for the laser light,means for flowing a gaseous medium in said waveguide in the transverse electric field, andmeans for exciting said medium to produce a population inversion therein and to stimulate the desired emission of radiation;
- characterized in that;
the cathode means includes means for preionizing said medium via the Malter effect;
the exciting means includes means for applying a relatively higher voltage pulse between the opposed cathode and anode electrode means for preionizing said medium within said waveguide, and means for applying a relatively lower voltage between opposed electrode means for sustaining a discharge in the medium within the waveguide; and
the waveguide is free of other preionization means.
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Abstract
Preionization is achieved in transverse-discharge gaseous lasers by means of the Malter effect. In two embodiments, the preionization is achieved either with a metal electrode which is the cathode during preionization and then is the anode during the subsequent pumping phase, or by means of a separate set of preionization electrodes. These preionization cathodes are metal electrodes, such as aluminum or tantalum electrodes, exhibiting high secondary electron emission by the Malter effect. High-field electron emission from these preionization cathodes is inherently possible because of a thin insulating layer on the surface. This layer separates positive ions attracted to the surface from the conducting metal and thereby creates a very high field gradient over a very short distance. In a preferred embodiment, uniform initial ionization is created during the preionization phase of operation; and the excitation is supplied by an electric field which is lower than that required to sustain the discharge; and the active medium is enclosed in an optical waveguide free of interfering structure.
69 Citations
20 Claims
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1. A transverse excitation laser comprising
means defining an optical axis along which the laser light propagates, cathode and anode electrode means positioned in opposed relationship along said optical axis for establishing therealong a transverse electric field, insulating side wall members forming with said cathode and anode means a waveguide for the laser light, means for flowing a gaseous medium in said waveguide in the transverse electric field, and means for exciting said medium to produce a population inversion therein and to stimulate the desired emission of radiation; characterized in that;
the cathode means includes means for preionizing said medium via the Malter effect;
the exciting means includes means for applying a relatively higher voltage pulse between the opposed cathode and anode electrode means for preionizing said medium within said waveguide, and means for applying a relatively lower voltage between opposed electrode means for sustaining a discharge in the medium within the waveguide; and
the waveguide is free of other preionization means.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A transverse excitation laser comprising
means defining an optical axis along which the laser light propagates, electrode means positioned in opposed relationship along said optical axis for establishing therealong a transverse electric field, one of said electrode means being a solid base member and the other of said electrode means comprising a plurality of metallic segments, adjacent metallic segments being spaced apart by an interleaved plurality of insulating segments to form a continuous surface, insulating side wall members forming with said electrode means a waveguide for the laser light, a gaseous medium for flow in said waveguide in the transverse electric field, and means for exciting said medium to produce a population inversion and to stimulate the desired emission of radiation, characterized in that the exciting means includes a first voltage source for applying a relatively higher voltage pulse between the base member as anode and at least some of the metal segments as cathode for preionizing said medium and a second voltage source for applying a relatively lower voltage between said base member as cathode and at least some of the metal segments as anode for sustaining a discharge in said medium, the waveguide being free of other electrode means and opaque to the introduction of free electrons therein and the metal segments include an insulating surface layer for providing secondary electron emission for preionizing the medium.
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18. A transverse-excitation laser tube comprising means defining an optical waveguide including a metal base member forming one wall of the waveguide, a pair of spaced insulating members forming a pair of opposed side walls of the waveguide, and a composite member forming the fourth wall, said composite member comprising insulating segments and metallic segments alternating in the direction of waveguiding, each of the metallic segments including a surface portion having an insulating layer of a material taken from the group consisting of aluminum oxide, magnesium oxide, and tantalum oxide of a thickness at least 100 Angstroms,
means for flowing gas along the waveguide and electrode means for establishing operating voltages on the base member and the metallic segments.
Specification