Optical transmission apparatus

Abstract

Before being incident to a nonlinear medium, a short pulse is intensity-modulated with a bit string pattern, and then made incident. When the pulse light corresponding to a bit value ‘0’ is incident to the nonlinear medium, the pulse light is intensity-modulated so that the spectral width thereof is not spread to a predetermined spectral region due to the nonlinear phenomena, thereby producing a light state of being not output from an optical demultiplexer. Meanwhile, when the pulse light corresponding to a bit value ‘1’ is incident to the nonlinear medium, the pulse light is intensity-modulated so that the spectral width thereof is spread to the predetermined spectral region due to the nonlinear phenomena, thereby producing a light state of being output from the optical demultiplexer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of the conventional configuration of an optical transmission apparatus for performing data broadcast on a large-scale optical fiber transmission system.

FIGS. 2A, 2B show examples of the conventional configurations of an optical transmission apparatus for performing data broadcast on a large-scale optical fiber transmission system.

FIG. 3 shows an example of the conventional configuration of an optical transmission apparatus for performing data broadcast on a large-scale optical fiber transmission system.

FIGS. 4A-4C show diagrams illustrating optical characteristic on a wavelength axis and a time axis supplied from SC light source 10 in the configuration shown in FIG. 3.

FIG. 5 shows a diagram illustrating an example of the conventional configuration of an optical transmission apparatus for broadcast using SC light source 10.

FIGS. 6A-6C show diagrams illustrating optical characteristics on a wavelength axis and a time axis supplied from SC light source 10 in the configuration shown in FIG. 5.

FIGS. 7A-7C show diagrams explaining wavelength dispersion.

FIGS. 8A, 8B show diagrams explaining the principle of an optical transmission apparatus according to an embodiment of the present invention.

FIG. 9 shows a diagram illustrating the relationship of output light from optical intensity modulator 2 to output light from nonlinear medium 12.

FIG. 10 shows a diagram illustrating the relationship of distribution data to output light from optical wavelength demultiplexer 5.

FIG. 11 shows a diagram illustrating a first configuration example of an optical transmission apparatus according to an embodiment of the present invention.

FIG. 12 shows a chart illustrating the relationship of the peak power of the pulse input to nonlinear medium 12 to a spectral half-value width of the generated SC light.

FIG. 13 shows a diagram illustrating a second configuration example of an optical transmission apparatus according to an embodiment of the present invention.

FIG. 14 shows a diagram illustrating a third configuration example of an optical transmission apparatus according to an embodiment of the present invention.

Claims

1. An optical transmission apparatus comprising: a light source outputting either pulse light or continuous light;an intensity modulator having the light from the light source incident thereto, and outputting pulse light intensity-modulated with the light output from the light source according to a predetermined bit string pattern;a nonlinear medium having the pulse light from the intensity modulator incident thereto, bringing about nonlinear phenomena upon the pulse light supplied from the intensity modulator, and spreading the spectral width of the modulated pulse light having peak intensity of a predetermined level or higher to a predetermined spectral region; andan optical wavelength demultiplexer having the pulse light from the nonlinear medium incident thereto, and demultiplexing the pulse light having a wavelength component in the predetermined spectral region into light having a plurality of wavelengths to output.

2. The optical transmission apparatus according to claim 1, wherein, when the pulse light corresponding to a bit value ‘0’ is made incident to the nonlinear medium, the intensity modulator performs intensity modulation of the pulse light corresponding to the bit value ‘0’ so that the spectral width of said pulse light is not spread to the predetermined spectral region due to the nonlinear phenomena, whereas when the pulse light corresponding to a bit value ‘1’ is made incident to the nonlinear medium, the intensity modulator performs intensity modulation of the pulse light corresponding to the bit value ‘1’ so that the spectral width of said pulse light is spread to the predetermined spectral region due to the nonlinear phenomena.

3. The optical transmission apparatus according to claim 1, wherein, the light source is a mode-locked laser generating a short pulse.

4. The optical transmission apparatus according to claim 1, wherein, the light source is a direct-current light emitting laser generating continuous light.

5. The optical transmission apparatus according to claim 1, wherein, the light source is a mode-locked laser generating a short pulse, andthe intensity modulator is used in common with an intensity modulator for mode locking being incorporated in the mode-locked laser, and a signal having the bit string pattern superposed on a periodic signal for mode locking is supplied to the intensity modulator for mode locking.

6. The optical transmission apparatus according to claim 1, further comprising: an optical amplifier amplifying the pulse light from the intensity modulator,wherein the pulse light from the intensity modulator is amplified in the optical amplifier, and incident to the nonlinear medium.