Patent ID: 6563995
Filing Date: 2003-05-13
Classification: G02B,H01S

Abstract:
An apparatus for separating light at a first wavelength &lgr;1 from light at a second wavelength &lgr;2, where &lgr;12, said apparatus comprising:a) a core having a core cross-section and a refractive index no, said core comprising an optically active material having a first gain at said first wavelength &lgr;1 and a second gain at said second wavelength &lgr;2; b) a depressed cladding surrounding said core, said depressed cladding having a depressed cladding cross-section and a refractive index n1; and c) a secondary cladding surrounding said depressed cladding, said secondary cladding having a secondary cladding cross-section and a refractive index n2; wherein said core cross-section, said depressed cladding cross-section, said secondary cladding cross-section and said refractive indices no, n1, n2 are selected to produce: (i) a fundamental mode cutoff wavelength &lgr;c such that &lgr;1c2; and (ii) a loss at the second wavelength &lgr;2 at least equal to 70 dB less than said gain at said second wavelength &lgr;2.