Multi-wavelength light source and discrete-wavelength-variable light source

Abstract

In a light source for generating light containing multiple wavelengths substantially uniform in intensity, a wavelength demultiplexing element 10 (for example, waveguide-type wavelength selecting filter) demultiplexes input light into a plurality of wavelengths λ 1 through λ 32. Optical amplifiers 14 - 1 through 14 - 32 amplify outputs of the element 10 and applies them to input ports of a wavelength multiplexing element 12. The wavelength multiplexing element 12 wavelength-multiplexes their input. Output of the wavelength multiplexing element 12 is applied to a fiber coupler 16 which, in turn, applies one of its outputs to the wavelength demultiplexing element 10. The optical amplifiers 14 have a gain larger by approximately 10 dB than the loss in the optical loop made of the element 10, optical amplifier 14, element 12 and fiber coupler 16. The other output of the fiber coupler 16 is wavelength-multiplex light containing wavelengths λ 1 through λ 32.

1 . A multi-wavelength light source for outputting laser light containing different wavelengths simultaneously, comprising: 
 wavelength demultiplexing means for demultiplexing input light into a plurality of predetermined different wavelengths;    a plurality of optically amplifying means for amplifying said predetermined different wavelengths from said wavelength demultiplexing means individually;    wavelength multiplexing means for wavelength-multiplexing optical outputs of respective said optically amplifying means;    connecting means for connecting an output of said wavelength multiplexing means to an input of said wavelength demultiplexing means; and    output take-out means for taking out light circulating in a loop comprising of said wavelength demultiplexing means, said optically amplifying means, said wavelength multiplexing means and said connecting mean to the exterior of said loop.    
     
     
         2 . The multi-wavelength light source according to    claim 1    wherein said wavelength demultiplexing means demultiplexes said input light into a plurality of predetermined different wavelengths in predetermined wavelength intervals.  
     
     
         3 . The multi-wavelength light source according to    claim 2    wherein said wavelength demultiplexing means is a waveguide-type wavelength selecting filter.  
     
     
         4 . The multi-wavelength light source according to    claim 1    wherein said wavelength multiplexing means wavelength-multiplexes optical inputs having predetermined wavelengths which enter in respective said inputs.  
     
     
         5 . The multi-wavelength light source according to    claim 4    wherein said wavelength multiplexing means is a waveguide-type wavelength selecting filter.  
     
     
         6 . The multi-wavelength light source according to    claim 1    wherein said output take-out means is light splitting means for taking out light travelling through said connecting means.  
     
     
         7 . The multi-wavelength light source according to    claim 1    further comprising optical band pass filter means provided on said connecting means and transparent only to light within a predetermined wavelength band.  
     
     
         8 . The multi-wavelength light source according to    claim 1    further comprising optical modulating means provided on said optical loop for intensity-modifying circulating light in said optical loop in accordance with a modification signal, said modification signal having a frequency corresponding to an integer multiple of the circular frequency of said optical loop, and said light taken out by said output take-out means is pulsating light.  
     
     
         9 . The multi-wavelength light source according to    claim 8    wherein said means on said optical loop is of a polarization holding type.  
     
     
         10 . The multi-wavelength light source according to    claim 8    further comprising polarization adjusting means located in an input side of said optical modulating means.  
     
     
         11 . The multi-wavelength light source according to    claim 1    wherein each of said optically amplifying means can selectively supply or block its output to said wavelength multiplexing means.  
     
     
         12 . The multi-wavelength light source according to claim  10  wherein each of said optically amplifying means includes an optical amplifier for amplifying corresponding one of optical outputs from said wavelength demultiplexing means and optical switching means for supplying or blocking an output of said optical amplifier.  
     
     
         13 . A multi-wavelength light source for outputting laser light containing a plurality of collectively modified wavelengths, comprising: 
 wavelength demultiplex/amplify/multiplexing means for demultiplexing input light into a plurality of predetermined different wavelengths, then optically amplifying them individually, and wavelength-multiplexing them;    polarizing means for extracting predetermined polarized components from output light of said wavelength demultiplex/amplify/multiplexing means;    light splitting means for splitting output light of said polarizing means;    depolarizing means for depolarizing one of optical outputs of said light splitting means and for applying it to wavelength demultiplex/amplify/multiplexing means; and    modulating means for modulating the other optical output of said splitting means in accordance with a modulation signal.    
     
     
         14 . The multi-wavelength light source according to    claim 13    further comprising first polarization adjusting means located between one of outputs of said splitting means and input of said depolarizing means.  
     
     
         15 . The multi-wavelength light source according to    claim 13    further comprising second polarization adjusting means located between the other output of said splitting means and input of said modulating means.  
     
     
         16 . The multi-wavelength light source according to claim  13  wherein said wavelength demultiplex/amplify/multiplexing means comprises wavelength demultiplexing means for demultiplexing input light into predetermined different wavelengths in predetermined wavelength intervals, a plurality of optically amplifying means for amplifying said wavelengths demultiplexed by said wavelength demultiplexing means individually, and wavelength multiplexing means for wavelength-multiplexing optical outputs from respective said optically amplifying means.  
     
     
         17 . The multi-wavelength light source according to    claim 16    wherein said wavelength demultiplexing means and said wavelength multiplexing means are waveguide-type wavelength selecting filters.  
     
     
         18 . A multi-wavelength light source for outputting ASE light containing a plurality of wavelengths, comprising: 
 wavelength demultiplex/amplify/multiplexing means for demultiplexing input light into a plurality of predetermined different wavelengths, then optically amplifying them individually, and wavelength-multiplexing them;    wavelength shifting means for slightly shifting wavelengths in output light from said wavelength demultiplex/amplify/multiplexing means and for returning it back to input of said wavelength demultiplex/amplify/multiplexing means; and    output take-out means for taking out light which is circulated by said wavelength demultiplex/amplify/multiplexing means and said wavelength shifting means.    
     
     
         19 . The multi-wavelength light source according to    claim 18    wherein said wavelength demultiplex/amplify/multiplexing means and said output take-out means are of a polarization holding type.  
     
     
         20 . The multi-wavelength light source according to claim  18  further comprising first polarization adjusting means for adjusting polarization of output light from said wavelength demultiplex/amplify/multiplexing means and for supplying it to said wavelength shifting means.  
     
     
         21 . The multi-wavelength light source according to    claim 18    further comprising depolarizing means for depolarizing output light from said wavelength shifting means and for supplying it to said wavelength demultiplex/amplify/multiplexing means.  
     
     
         22 . The multi-wavelength light source according to    claim 21    wherein said depolarizing means comprises second polarization adjusting means for adjusting polarization of output light from said wavelength shifting means, and a depolarizing element for depolarizing output light from said second polarization adjusting means.  
     
     
         23 . The multi-wavelength light source according to    claim 21    wherein said output take-out means is located between output of said depolarizing means and input of said wavelength demultiplex/amplify/multiplexing means.  
     
     
         24 . The multi-wavelength light source according to    claim 18    wherein said wavelength shifting means is an acousto-optic modulator.  
     
     
         25 . The multi-wavelength light source according to    claim 18    wherein said wavelength demultiplex/amplify/multiplexing means comprises wavelength demultiplexing means for demultiplexing input light into predetermined different wavelengths in predetermined wavelength intervals, a plurality of optically amplifying means for amplifying said wavelengths demultiplexed by said wavelength demultiplexing means individually, and wavelength multiplexing means for wavelength-multiplexing optical outputs from respective said optically amplifying means.  
     
     
         26 . The multi-wavelength light source according to    claim 25    wherein said wavelength demultiplexing means and said wavelength multiplexing means are waveguide-type wavelength selecting filters.  
     
     
         27 . A multi-wavelength light source for outputting light containing a plurality of individually modified wavelengths, comprising: 
 wavelength demultiplexing means for demultiplexing input light into a plurality of different wavelengths;    a plurality of optically amplifying means each for amplifying one of said different wavelengths from said wavelength demultiplexing means individually;    a plurality of splitting means each for splitting optical output from associated one of said optically amplifying means;    first wavelength multiplexing means for wavelength-multiplexing first optical outputs of said splitting means and supplying the multiplexed output to said wavelength demultiplexing means;    a plurality of optical modulating means capable of modulating second optical output of said splitting means individually; and    second wavelength multiplexing means for wavelength-multiplexing outputs of said optical modulating means.    
     
     
         28 . The multi-wavelength light source according to    claim 27    wherein said wavelength demultiplexing means demultiplexes said input light into different predetermined wavelengths in predetermined wavelength intervals.  
     
     
         29 . The multi-wavelength light source according to    claim 27    wherein said wavelength demultiplexing means is a waveguide-type wavelength selective filter.  
     
     
         30 . The multi-wavelength light source according to    claim 27    wherein said first and second wavelength demultiplexing means wavelength-multiplex optical inputs entering in its inputs and having predetermined wavelengths.  
     
     
         31 . The multi-wavelength light source according to    claim 30    wherein said first and second wavelength multiplexing means are waveguide-type wavelength selecting filters.  
     
     
         32 . A discrete-wavelength-variable light source for selectively supplying one or more of discrete wavelengths contained in output laser light, comprising: 
 selective demultiplex/amplifying means for selectively demultiplexing one or more predetermined wavelengths from input light and optically amplifying them; and    optical splitting means for part of optical output from said selective demultiplex/amplifying means to an input of said selective demultiplex/amplifying means and for externally supplying the remainder of said optical output from said selective demultiplex/amplifying means.    
     
     
         33 . The discrete-wavelength-variable light source according to    claim 31    wherein said selective demultiplex/amplifying means comprises wavelength demultiplexing means for demultiplexing input light into a plurality of predetermined wavelengths, first optical switch means for selecting one of said wavelength components from said wavelength demultiplexing means, and optically amplifying means for amplifying optical output of said first optical switch means.  
     
     
         34 . The discrete-wavelength-variable light source according to    claim 33    wherein said selective demultiplex/amplifying means further comprises wavelength multiplexing means for wavelength-multiplexing a plurality of optical inputs with wavelength multiplexing characteristics consistent with input ports, and second optical switch means for supplying optical output of said optically amplifying means to one of input ports of said wavelength multiplexing means corresponding to the wavelength selected by said first optical switch means.  
     
     
         35 . The discrete-wavelength-variable light source according to    claim 35    wherein said wavelength demultiplexing means demultiplexes said input light into predetermined wavelengths in predetermined wavelength intervals.  
     
     
         36 . The discrete-wavelength-variable light source according to    claim 35    wherein said wavelength demultiplexing means is a waveguide-type wavelength selecting filter.  
     
     
         37 . The discrete-wavelength-variable light source according to    claim 34    wherein said wavelength multiplexing means is a waveguide-type wavelength selecting filter.  
     
     
         38 . The discrete-wavelength-variable light source according to    claim 32    further comprising optical modulating means provided on an optical loop made of said selective demultiplex/amplifying means and said optical splitting means to intensity-modulate circulating light in said optical loop in accordance with a modulation signal, said modulation signal having a frequency which is an integer multiple of a frequency circulating in said optical loop, said remainder of said optical output from said optical splitting means being pulsating light.  
     
     
         39 . The discrete-wavelength-variable light source according to    claim 38    wherein said selective demultiplex/amplifying means and said optical splitting means are of a polarization holding type.  
     
     
         40 . The discrete-wavelength-variable light source according to    claim 38    further comprising polarization adjusting means located in an input side of said optical modulating means.