Dielectric coupled CO
View Patent ↗An slab CO2 laser includes spaced-apart elongated slab electrodes. A lasing gas fills a discharge gap between the electrodes. An RF power supply is connected across the electrodes and sustains an electrical discharge in the lasing gas in the discharge gap. Either one or two ceramic inserts occupy a portion of width of the electrodes and in contact with the electrodes. A discharge gap is formed between the portions of the width of the electrodes not occupied by the insert or inserts. Provision of the ceramic insert or inserts increases the resistance-capacitance (RC) time constant of the electrode impedance by increasing the capacitive component of the time constant. This hinders the formation of arcs in the discharge, which, in turn enables the inventive laser to operate with higher excitation power or higher lasing-gas pressure than would be possible without the dielectric insert. The ceramic insert also decreases the difference in impedance of the electrodes with and without a discharge. This leads to a better-behaved discharge, and a discharge that is easier to light.
1. A laser comprising:
first and second elongated electrodes,
said first and second electrodes each having a stepped cross-section including a thick portion and a thin portion, said thin portion of said first electrode being wider than said thick portion of said second electrode, said electrodes having a step height defined by the difference in thickness between said thick and thin portions thereof;
said electrodes being arranged spaced apart and face-to-face with said thin and thick portions of said first electrode facing respectively said thick and thin portions of said second electrode, where the spacing between said electrodes being arranged such that an elongated discharge gap is formed between said thin portion of said first electrode and said thick portion of said second electrode, said discharge gap having a height and a width, said discharge gap width being about equal to the width of said thick portion of said second electrode and said discharge gap being filled with a lasing gas;
a solid dielectric insert extending longitudinally along the length of said electrodes, said insert having a height less than said step height and being located between said thick portion of said first electrode and said thin portion of said second electrode and in contact therewith;
a pair of mirrors configured and arranged to define a laser resonant cavity extending through said elongated discharge gap;
means for exciting said lasing gas to create a gas discharge in said discharge gap, thereby causing laser radiation to circulate in said resonant cavity; and
wherein the height of said discharge gap is selected such that said gap forms a waveguide for said laser radiation in the height direction, and the width of said gap is selected such that said laser radiation is allowed to propagate in free space in the width direction of said gap in a manner controlled by said configuration and arrangement of said mirrors.
2. The laser of claim 1 , wherein said dielectric insert has a width greater than the width of said thin portion of said second electrode, extends laterally beyond corresponding outer edges of said first and second electrodes and extends laterally beyond said thick portion of said first electrode toward said thick portion of said second electrode.
3. The laser of claim 2 , wherein said dielectric insert is in contact with said thick portion of said second electrode.
4. A laser comprising:
first and second elongated electrodes,
said first and second electrodes each having a stepped cross-section, said first electrode including two thick portions bounding a thin portion and said second electrode including two thin portions bounding a thick portion, said thin portion of said first electrode being wider than said thick portion of said second electrode, said electrodes having a step height defined by the difference in thickness between said thick and thin portions thereof;
said electrodes being arranged spaced apart and face-to-face with said thin and thick portions of said first electrode facing respectively said thick and thin portions of said second electrode, spacing between said electrodes being arranged such that an elongated discharge gap is formed between said thin portion of said first electrode and said thick portion of said second electrode, said discharge gap having a height and a width, said discharge gap width being about equal to the width of said thick portion of said second electrode and said discharge gap being filled with a lasing gas;
two solid dielectric inserts extending longitudinally along the length of said electrodes, said inserts having a height less than said step height and one thereof being located between each said thick portions of said first electrode and said thin portions of said second electrode and in contact therewith;
a pair of mirrors configured and arranged to define a laser resonant cavity extending through said elongated discharge gap;
means for exciting said lasing gas to create a gas discharge in said discharge gap, thereby causing laser radiation to circulate in said resonant cavity; and
wherein the height of said discharge gap is selected such that said gap forms a waveguide for said laser radiation in the height direction, and the width of said gap is selected such that said laser radiation is allowed to propagate in free space in the width direction of said gap in a manner controlled by said configuration and arrangement of said mirrors.
5. The laser of claim 4 , wherein each of said dielectric inserts has a width greater than the width of said thin portions of said second electrode and extend laterally beyond corresponding outer edges of said first and second electrodes and extend laterally beyond said thick portions of said first electrode toward said thick portion of said second electrode.
6. The laser of claim 5 , wherein said dielectric insert is in contact with said thick portion of said second electrode.