Cascaded Raman laser
View Patent ↗A cascaded Raman laser ( 10 ) has a pump radiation source ( 12 ) emitting at a pump wavelength λ p , an input section ( 14 ) and an output section ( 16 ) made of an optical medium. Each section ( 14, 16 ) comprises wavelength selectors ( 141, 142, . . . , 145 and 161, 162, . . . , 165 ) for wavelengths λ 1 , λ 2 , . . . , λ n−k , where n≧3, λ p <λ 1 <λ 2 < . . . <λ n−1 <λ n and λ n−k+1 , λ n−k+2 , . . . , λ n being k≧1 emitting wavelengths of the laser ( 10 ). The laser further comprises an intracavity section ( 18 ) that is made of a non-linear optical medium, has a zero-dispersion wavelength λ 0 and is disposed between the input ( 14 ) and the output ( 16 ) section. The wavelengths λ 1 , λ 2 , . . . , λ n−k of the wavelength selectors ( 141, 142, . . . , 145 and 161, 162, . . . , 165 ) and the zero-dispersion wavelength λ 0 of the intracavity section ( 18 ) are chosen such that energy is transferred between different wavelengths by multi-wave mixing.
1. A cascaded Raman laser comprising:
a) a pump radiation source emitting at a pump wavelength λ p ,
b) an input section and an output section made of an optical medium, each section comprising wavelength selectors for wavelengths λ 1 , λ 2 , . . . , λ n−k , where n≧3, λ p <λ 1 <λ 2 < . . . <λ n−1 <λ n and λ n−k+1 , λ n−k+2 , . . . , λ n being k≧1 emitting wavelengths of the laser, and
c) an intracavity section that is made of a non-linear optical medium, has a zero-dispersion wavelength λ 0 and is disposed between the input and the output section,
wherein
d) the wavelengths λ 1 , λ 2 , . . . , λ n−k of the wavelength selectors and the zero-dispersion wavelength λ 0 of the intracavity section are chosen such that energy is transferred between radiation of different wavelengths by multi-wave mixing.
2. The laser of claim 1 , wherein at least one of the emitting wavelengths λ n−k+1 , λ n−k+2 , . . . , λ n of the laser is involved in multi-wave mixing.
3. The laser of claim 1 , wherein the wavelengths λ 1 , λ 2 , . . . , λ n−k of the wavelengths selectors are chosen so that energy transfer by multi-wave mixing involves at least three adjacent wavelengths.
4. The laser of claim 3 , wherein the wavelengths λ 1 , λ 2 , . . . , λ n−k of the wavelength selectors are chosen so that
1/λ i =1/λ i−1 +1/λ i−2 −1/λ i−3 ,
where i=3, 4, . . . , n, and that the zero-dispersion wavelength λ 0 of the intracavity section substantially equals (λ i−1 +λ i−2 )/2.
5. The laser of claim 3 , wherein the wavelengths λ 1 , λ 2 , . . . , λ n−k of the wavelengths selectors are chosen so that
1/λ i =2/λ i−1 −1/λ i−2 ,
where i=3, 4, . . . , n, and that the zero-dispersion wavelength λ 0 of the intracavity section substantially equals λ i−1 .
6. The laser of claim 1 , wherein the wavelengths λ 1 , λ 2 , . . . , λ n−k of the wavelengths selectors are chosen so that energy transfer by multi-wave mixing involves at least three nonadjacent wavelengths.
7. The laser of claim 6 , wherein k=2 and that the wavelengths λ 1 , λ 2 , . . . , λ n−2 of the wavelengths selectors are chosen so that
1/λ i =1/λ i−2 +1/λ i−3 −1/λ i−5
and
1/λ i−1 =1/λ i−2 +1/λ i−3 −1/λ i−4 ,
where i=5, 6, . . . , n, and that the zero-dispersion wavelength λ 0 of the intracavity section substantially equals (λ i−2 +λ i−3 )/2.
8. The laser of claim 6 , wherein k=2 and that the wavelengths λ 1 , λ 2 , . . . , λ n−1 of the wavelengths selectors are chosen so that
1λ i =2/λ i−2 −1/λ i−4
and
1/λ i−1 =2/λ i−2 −1/λ i−3 ,
where i=5, 6, . . . , n, and that the zero-dispersion wavelength λ 0 of the intracavity section substantially equals λ i−2 .
9. The laser of claim 1 , wherein for each emitting wavelength an additional wavelength selector for wavelength λ n−k+1 , λ n−k+2 , . . . , λ n , respectively, is provided in the input section ( 14 ) and in the output section.
10. The laser of claim 1 , wherein the wavelength selectors are reflectors having center wavelengths λ 1 , λ 2 , . . . , λ n−k .