Wavelength determining apparatus, method and program for thin film thickness monitoring light

Abstract

A multi-layer optical thin film filter comprising plural deposited optical thin films, wherein optical thin film thickness for each of said optical thin films has a predetermined wavelength spectrum in a predetermined gain equalization band and a predetermined wavelength spectrum in a pumping light transmission band other than said gain equalization band.

1 . A multi-layer optical thin film filter comprising plural deposited optical thin films, wherein optical thin film thickness for each of said optical thin films has a predetermined wavelength spectrum in a predetermined gain equalization band and a predetermined wavelength spectrum in a pumping light transmission band other than said gain equalization band.  
   
   
       2 . The multi-layer optical thin film filter as claimed in  claim 1 , wherein the optical thickness for each of said optical thin film is designed by fitting calculation using predetermined initial optical thickness so as to lessen a first error between a theoretical value which expresses a wavelength profile in said gain equalization band with using the optical thickness for each of said optical thin films as parameter and a target wavelength spectrum value in the corresponding gain equalization band, and a second error between a theoretical value which expresses a wavelength spectrum in said pumping light transmission band with using the optical thickness for each of said optical thin films as parameter and a target wavelength spectrum value in the corresponding pumping light transmission band.  
   
   
       3 . The multi-layer optical thin film filter as claimed in  claim 2 , wherein an initial value of the optical thin film thickness for each of said optical thin films during said fitting is designed so that a cutting off wavelength band in said wavelength profile does not overlap said pumping light wavelength band.  
   
   
       4 . The multi-layer optical thin film filter as claimed in  claim 3 , wherein an initial value of optical thickness for each of said optical thin films during said fitting is designed so that an edge of a short wavelength side of said cutting off wavelength band in the wavelength profile overlaps said wavelength band for gain equalization.  
   
   
       5 . A multi-layer optical thin film filter, wherein optical thin film thickness for each of said optical thin films is designed by fitting with using desired optical thin film thickness for an initial value so as to lessen a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than predetermined pumping light wavelength band with using optical thin film thickness for each of optical thin films and target wavelength values in a predetermined wavelength band, and a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a wavelength profile value in the corresponding pumping light wavelength band in the case that a transmission rate corresponding to a target wavelength profile in said pumping light wavelength band is smaller than a minimum transmission rate required in said pumping light wavelength band.  
   
   
       6 . The multi-layer optical thin film filter as claimed in  claim 5 , wherein said second error between said theoretical value which expresses the wavelength profile in said pumping light wavelength band with using the optical thin film thickness for each of said optical thin films as parameter and said wavelength profile value in the corresponding pumping light wavelength band becomes zero in the case that the transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is larger than the minimum transmission rate required in said pumping light wavelength band.  
   
   
       7 . A multi-layer optical thin film filter comprising plural deposited optical thin films, wherein optical thin film thickness for each of said optical thin films is designed by fitting with using predetermined optical thin film thickness for an initial value so as to lessen a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of optical thin films and a target wavelength value in a predetermined wavelength band, and a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a wavelength profile value in the corresponding pumping light wavelength band in the case that a transmission rate corresponding to a target wavelength profile in said pumping light wavelength band is larger than an allowable maximum transmission rate required in said pumping light wavelength band.  
   
   
       8 . The multi-layer optical thin film filter as claimed in  claim 7 , wherein said second error between said theoretical value which expresses the wavelength profile in said pumping light wavelength band with using the optical thin film thickness for each of said optical thin films as parameter and said wavelength profile value in the corresponding pumping light wavelength band becomes zero in the case that the transmission rate corresponding to a target wavelength profile in said pumping light wavelength band is smaller than an allowable maximum transmission rate required in said pumping light wavelength band.  
   
   
       9 . A designing method for a multi-layer optical thin film filter comprising plural deposited optical thin films to design thin film thickness for each of said optical thin films, comprising a step to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of optical thin films and a target wavelength value in a desired wavelength band, and a step to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a wavelength profile value in the corresponding pumping light wavelength band, and a step to design optical thin film thickness for each of said optical thin films so as to lessen the calculated first and second errors respectively.  
   
   
       10 . A designing method for a multi-layer optical thin film filter comprising plural deposited optical thin films to design thin film thickness for each of said optical thin films, comprising a step to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of said optical thin films and a target wavelength value in a predetermined wavelength band, and a step to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a wavelength profile value in the corresponding pumping light wavelength band in the case that a transmission rate corresponding to a target wavelength profile in said pumping light wavelength band is smaller than a minimum transmission rate required in said pumping light wavelength band, and a step to design optical thin film thickness for each of said optical thin films by fitting with using predetermined optical thin film thickness for an initial value so as to lessen the calculated first and second errors respectively.  
   
   
       11 . The designing method for a multi-layer optical thin film filter as claimed in  claim 10  comprising a step that the second error between the theoretical value which expresses the wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and the wavelength profile value in the corresponding pumping light wavelength band becomes zero in the case that the transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is larger than the minimum transmission rate required in said pumping light wavelength band.  
   
   
       12 . A designing method for a multi-layer optical thin film filter comprising plural deposited optical thin films to design optical thin film thickness for each of said optical thin films, comprising a step to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of said optical thin films and a target wavelength value in a desired wavelength band, and a step to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a wavelength profile value in the corresponding pumping light wavelength band in the case that a transmission rate corresponding to a target wavelength profile in said pumping light wavelength band is larger than an allowable maximum transmission rate in said pumping light wavelength band, and a step to design optical thin film thickness for each of said optical thin films by fitting with using predetermined optical thin film thickness for an initial value so as to lessen the calculated first and second errors respectively.  
   
   
       13 . The designing method for a multi-layer optical thin film filter as claimed in  claim 12  comprising a step to the second error between the theoretical value which expresses the wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and the wavelength profile value in the corresponding pumping light wavelength band becomes zero in the case that the transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is smaller than the allowable maximum transmission rate in said pumping light wavelength band.  
   
   
       14 . A thin film thickness designing apparatus for a multi-layer optical thin film filter comprising plural deposited optical thin films, comprising a means to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band using optical thin film thickness for each of said optical thin films and a target wavelength value in a predetermined wavelength band, and a means to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a target wavelength profile value in the corresponding pumping light wavelength, and a means to design optical thin film thickness for each of said optical thin films by fitting with using predetermined optical thin film thickness for an initial value so as to lessen the calculated first and second errors respectively.  
   
   
       15 . A thin film thickness designing apparatus for a multi-layer optical thin film filter comprising plural deposited optical thin films, comprising a means to calculate a first error between a theoretical value which expresses a wavelength profile in predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of said optical thin films and a target wavelength value in a predetermined wavelength band, and a means to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a wavelength profile value in the corresponding pumping light wavelength in the case that a transmission rate corresponding to a target wavelength profile in said pumping light wavelength band is smaller than an allowable maximum transmission rate in said pumping light wavelength band, and a means to design optical thin film thickness for each of said optical thin films by fitting with using predetermined optical thin film thickness for an initial value so as to lessen the calculated first and second errors respectively.  
   
   
       16 . The thin film thickness designing apparatus for a multi-layer optical thin film filter as claimed in  claim 15 , comprising a means that the second error between the theoretical value which expresses the wavelength profile in said pumping light wavelength band with using the optical thin film thickness of each of said optical thin films as parameter and the wavelength profile value in the corresponding pumping light wavelength becomes zero in the case that the transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is smaller than the allowable maximum transmission rate in said pumping light wavelength band.  
   
   
       17 . A thin film thickness designing apparatus for a multi-layer optical thin film filter comprising plural deposited optical thin films, comprising a means to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of said optical thin films and a target wavelength value in a predetermined wavelength band, and a means to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a wavelength profile value in the corresponding pumping light wavelength band in the case that transmission rate to correspond to target wavelength profile in said pumping light wavelength band is larger than an allowable maximum transmission rate in said pumping light wavelength band, and a means to design optical thin film thickness for each of said optical thin films by fitting with using predetermined optical thin film thickness for an initial value so as to lessen the calculated first and second errors respectively.  
   
   
       18 . The thin film thickness designing apparatus for a multi-layer optical thin film filter as claimed in  claim 17 , comprising a means that the second error between the theoretical value which expresses the wavelength profile in said pumping light wavelength band with using the optical thin film thickness for each of said optical thin films as parameter and the target wavelength profile value in the corresponding pumping light wavelength becomes zero in the case that the transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is smaller than the allowable maximum transmission rate in said pumping light wavelength band.  
   
   
       19 . A computer program performed by a computer for a multi-layer optical thin film filter comprising plural deposited optical thin films to design thin film thickness for each of said optical thin films, comprising a means to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of said optical thin films and a target wavelength value in a predetermined wavelength band, and a means to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a target wavelength profile value in the corresponding pumping light wavelength, and a means to design optical thin film thickness for each of said optical thin films so as to lessen the calculated first and second errors respectively.  
   
   
       20 . A computer program performed by a computer for a multi-layer optical thin film filter comprising plural deposited optical thin films to design thin film thickness for each of said optical thin films, comprising a means to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of said optical thin films and a target wavelength value in a predetermined wavelength band, and a means to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with optical thin film thickness for each of said optical thin films as parameter and a target wavelength profile value in the corresponding pumping light wavelength, and a means to design optical thin film thickness for each of said optical thin films so as to lessen the calculated first and second errors respectively.  
   
   
       21 . The computer program performed by a computer for a multi-layer optical thin film filter as claimed in  claim 20 , comprising a means that the second error between the theoretical value which expresses the wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and the target wavelength profile value in the corresponding pumping light wavelength becomes zero in the case that the transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is larger than the minimum transmission rate required in said pumping light wavelength band.  
   
   
       22 . A computer program performed by a computer for a multi-layer optical thin film filter comprising plural deposited optical thin films to design thin film thickness of each of optical thin films, comprising a means to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of said optical thin films and a target wavelength value in a predetermined wavelength band, and a means to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a target wavelength profile value in the corresponding pumping light wavelength in the case that a transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is larger than an allowable maximum transmission rate in said pumping light wavelength band, and a means to design optical thin film thickness for each of said optical thin films by fitting with using predetermined optical thin film thickness for an initial value so as to lessen the calculated first and second errors respectively.  
   
   
       23 . The computer program performed by a computer for a multi-layer optical thin film filter as claimed in  claim 22 , comprising a means that the second error between the theoretical value which expresses the wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films and the target wavelength profile value in the corresponding pumping light wavelength becomes zero in the case that the transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is smaller than the maximum allowable transmission rate in said pumping light wavelength band.  
   
   
       24 . An optical amplifier comprising an rare earth element doped optical fiber to amplify an optical signal, an pumping light source which projects pumping light to excite said rare earth element, a combiner which combines pumping light projected by said pumping light source with said optical signal and projects said pumping light to said rare earth element doped optical fiber, and the multi-layer thin film filter as claimed in  claim 1  which is located in an output side for pumping light of said combiner and a down stream side for said optical signal.  
   
   
       25 . A wavelength division multiplex system which transmits plural optical signals with different wavelength, comprising an optical sender to send said plural optical signals to an optical transmission route, the optical amplifier as claimed in  claim 24  which amplifies said plural optical signals sent by said sender and transmitted though said optical transmission route in a lump, and an optical receiver which receives said plural optical signals amplified by said optical amplifier and transmitted through said optical transmission route.