Optical amplification module, optical amplifier, optical communication system, and white light source
The present invention relates to an optical amplifier and the like having a flatter gain spectrum in the wavelength band of 1490 nm to 1520 nm than before. The optical amplifier according to the present invention comprises an Er-doped optical waveguide and a Tm-doped optical waveguide having gain spectra difference from each other in the wavelength band. The signal light entered through the input end is first amplified by the Er-doped optical waveguide, and thereafter is amplified by the Tm-doped optical waveguide. The gain deviation of the amplified signal light, which has been amplified in the Er- and Tm-doped optical waveguides and outputted through the output end, can be reduced over the wavelength band.
1. An optical amplification module having an amplification band within a range of 1490 nm to 1520 nm, comprising:
an Er-doped optical waveguide having an optical waveguide region doped with Er;
a pumping light source optically connected to one end of said Er-doped optical waveguide through an optical coupler, whereby pumping light generated in said pumping light source is supplied into said Er-doped optical waveguide;
a temperature adjustor including a section which is arranged adjacent to said Er-doped optical waveguide, said temperature adjustor adjusting a temperature of said Er-doped optical waveguide and maintaining the temperature of said Er-doped optical waveguide at a predetermined temperature higher than room temperature, on the basis of the result of the detection; and
a cutoff filter provided on an optical path between an input end and an output end of said optical amplification module, said cutoff filter cutting off light in a wavelength band of 1530 nm or more so as to remove amplified spontaneous emission light in C-band.
2. An optical amplification module according to claim 1 , wherein said temperature adjustor maintains the temperature of said Er-doped optical waveguide at 65° C. or more.
3. An optical amplification method, comprising the steps of:
preparing an optical amplification module that comprises; an Er-doped optical waveguide having an optical waveguide region doped with Er; a pumping light source supplying pumping light into said Er-doped optical fiber; and a temperature adjustor performing a temperature control for said Er-doped optical fiber separate from a temperature control for said pumping light source;
controlling said temperature adjustor so as to maintain temperature of said Er-doped optical waveguide at a predetermined temperature higher than room temperature;
amplifying light within a wavelength range of 1490 nm to 1520 nm; and
sending the amplified signal through a cutoff filter cutting off light in a wavelength band of 1530 nm or more.
4. An optical amplification method according to claim 3 , wherein said temperature adjustor reduces a gain deviation of said Er-doped optical fiber in the wavelength range by adjusting the temperature of said Er-doped optical fiber at the predetermined temperature higher than room temperature.
5. An optical amplification method according to claim 3 , wherein said temperature adjustor reduces a relative gain deviation of said Er-doped optical fiber in the wavelength range by adjusting the temperature of said Er-doped optical fiber at the predetermined temperature higher than room temperature.
6. An optical amplification method according to claim 3 , wherein said temperature adjustor increases a gain of said Er-doped optical fiber in the wavelength range by adjusting the temperature of said Er-doped optical fiber at the predetermined temperature higher than room temperature.
7. An optical amplification module according to claim 1 , wherein said cutoff filter equalizes a gain of light in the range of 1490 to 1520 nm.
8. An optical amplification method according to claim 3 , wherein said cutoff filter equalizes a gain of light in the range of 1490 to 1520 nm.