Method and apparatus for the operation of ring laser in a biased mode

Claim 5

The method according to claim 1 further comprising suppressing all other oscillations in said ring laser.

Claim 6

Method according to claim 1 wherein said first and second cavity modes are TEMooq modes whose axial mode numbers q differ by unity.

Claim 7

The method according to claim 1 comprising disposing a saturable absorber in said ring cavity, said absorber having a primarily inhomogeneously broadened resonance line, the center frequency thereof being substantially coincident with the center frequency of the resonance line of the gain medium, and tuning said ring cavity so that the mean value of the resonant frequencies of said first and second cavity modes is substantially equal to the center frequency of the resonance line of said saturable absorber.

Claim 8

The method according to claim 4 wherein said gain medium comprises helium-neon and said saturable absorber comprises methane, said resonance line occurring at a wave length of 3.39 microns.

Claim 9

The method according to claim 4 wherein said gain medium comprises helium-neon and said saturable absorber comprises excited neon, said resonance line occurring at a wave length of 0.6328 microns.

Claim 10

The method according to claim 4 comprising the initial steps of raising the gain of said gain medium to a level sufficient to support oscillation on a single cavity resonance and tuning the ring cavity so that the frequency of said cavity resonance differs from the center frequency of the resonance line of the saturable absorber by at least a homogeneous absorption linewidth to establish one of said traveling waves unidirectionally.

Claim 11

The method according to claim 7 wherein the ring cavity tuning in the initial steps is within a homogeneous gain linewidth of the center frequency of the resonance line of the gain medium.

Claim 12

The method according to claim 4 comprising tuning the ring cavity to a stationary point on the intensity-tuning curve derived from at least one of said traveling waves.

Claim 13

The method according to claim 4 additionally comprising stabilizing said ring laser by servo tuning the ring cavity in response to the intensity of at least one of said traveling waves at a stationary point thereof.

Claim 14

The method according to claim 1 wherein said gain medium is inhomogeneously broadened and comprising the step of tuning said ring cavity so that the frequency of one of said traveling waves is within a homogeneous linewidth of the center frequency of the resonance line of the gain medium and the frequency of the other of said traveling waves differs from the center frequency by at least a homogeneous linewidth.

Claim 17

The method according to claim 12 further comprising suppressing all other oscillations in said ring laser.

Claim 18

The method according to claim 12 comprising disposing a saturable absorber in said ring laser, said absorber having a primarily inhomogeneously broadened resonance line, the center frequency thereof being substantially coincident with the center frequency of the resonance line of the laser.

Claim 19

The method according to claim 14 comprising tuning said ring laser so that the mean value of the resonant frequencies of said cavity modes is substantially equal to the center frequency of the resonance line of said saturable absorber.

Claim 20

The method according to claim 15 wherein said gain medium comprises helium-neon and said saturable absorber comprises methane, said resonance line occurring at a wavelength of 3.39 microns.

Claim 21

The method according to claim 15 wherein said gain medium comprises helium-neon and said saturable absorber comprises excited neon, said resonance line occurring at a wavelength of 0.6328 microns.

Claim 22

The method according to claim 12 wherein said gain medium is inhomogeneously broadened and comprising the step of tuning said ring cavity so that the frequency of one of said traveling waves is within a homogeneous linewidth of the center frequency of the resonance line of the gain medium and the frequency of the other of said traveling waves differs from the center frequency by at least a homogeneous linewidth.

Claim 23

A ring laser operative in a biased mode comprising at least three reflector means defining a single ring cavity, a gain medium for providing laser action disposed in said ring cavity, a saturable absorber disposed in said ring cavity, said absorber having a primarily inhomogeneously broadened resonance line, the center frequency thereof being substantially coincident with the center frequency of the resonance line of the gain medium, and tuning means for varying the path length of said ring cavity so that the mean value of the resonant frequencies of two different cavity modes of said ring cavity is substantially equal to the center frequency of the resonance line of said saturable absorber to establish the simultaneous oscillation of first and second counter-directed traveling waves of differing frequencies on said two different cavity modes of the same ring cavity.

Claim 24

A ring laser operative in a biased mode comprising at least three reflector means defining a single ring cavity, a gain medium for providing laser action disposed in said ring cavity, a saturable absorber disposed in said ring cavity, said absorber having a primarily inhomogeneously broadened resonance line, the center frequency thereof being substantially coincident with the center frequency of the resonance line of the gain medium, and tuning means for varying the path length of said ring cavity so that the mean value of the resonant frequencies of two different cavity modes of said ring cavity is substantially equal to the center frequency of the resonance line of said saturable absorber to establish the simultaneous oscillation of first and second counter-directed traveling waves of differing frequencies on said two different cavity modes of the same ring cavity.

Claim 25

Apparatus according to claim 19 wherein said tuning means comprises detector means for detecting the intensity of at least one of said traveling waves and servo means for positioning at least one of said reflectors in response to the detected signal from said detector means at a stationary point thereof.

Claim 26

Apparatus according to claim 20 wherein said servo means comprises a voltage controlled piezoelectric element carrying one of said reflectors.

Claim 27

Apparatus according to claim 19 wherein said gain medium comprises helium-neon and said saturable absorber comprises methane, said center frequency occurring at a wavelength of 3.39 microns.

Claim 28

Apparatus according to claim 19 wherein said gain medium comprises helium-neon and said saturable absorber comprises excited neon, said center frequency occurring at a wavelength of 0.6328 microns.

Claim 29

A ring laser operative in a biased mode comprising at least three reflector means defining a single ring cavity, a gain medium for providing laser action disposed in said ring cavity, means for establishing the simultaneous oscillation of first and second counter-directed traveling waves of differing frequencies on different cavity modes of the same ring cavity and means for suppressing counter-directional oscillations of the same frequency as at least one of the first or second traveling waves.

Claim 30

A ring laser operative in a biased mode comprising at least three reflector means defining a single ring cavity, a gain medium for providing laser action disposed in said ring cavity, means for establishing the simultaneous oscillation of first and second counter-directed traveling waves of differing frequencies on different cavity modes of the same ring cavity and means for suppressing counter-directional oscillations of the same frequency as at least one of the first or second traveling waves.

Claim 31

Apparatus according to claim 24 wherein said means for establishing and said means for suppressing comprise a saturable absorber disposed in said ring cavity, said absorber having a primarily inhomogeneously broadened resonance line, the center frequency thereof being substantially coincident with the center frequency of the resonance line of the gain medium, and means for tuning said ring cavity so that the mean value of the resonant frequencies of said cavity modes is substantially equal to the center frequency of the resonance line of said saturable absorber.

Claim 32

A ring laser operative in a biased mode comprising at least three reflector means defining a single ring cavity, a gain medium for providing laser action disposed in said ring cavity, means for establishing the simultaneous oscillation of first and second counter-directed traveling waves of differing frequencies on different cavity modes of the same ring cavity and means for suppressing all other oscillations in said ring laser.

Claim 33

A ring laser operative in a biased mode comprising at least three reflector means defining a single ring cavity, a gain medium for providing laser action disposed in said ring cavity, means for establishing the simultaneous oscillation of first and second counter-directed traveling waves of differing frequencies on different cavity modes of the same ring cavity and means for suppressing all other oscillations in said ring laser.

Claim 34

Apparatus according to claim 26 wherein said means for establishing and said means for suppressing comprise a saturable absorber disposed in said ring cavity, said absorber having a primarily inhomogeneously broadened resonance line, the center frequency thereof being substantially coincident with the center frequency of the resonance line of the gain medium, and means for tuning said ring cavity so that the mean value of the resonant frequencies of said cavity modes is substantially equal to the center frequency of the resonance line of said saturable absorber.