| 摘要 |
PROBLEM TO BE SOLVED: To generate dispersion by applying temperature gradient and to change variance into a desired value by providing a temperature gradient applying means which a applies a temperature gradient in the optical signal propagation direction of an optical waveguide having a diffraction grating. SOLUTION: Temperature applying means 5a and 5b apply heat to an optical waveguide 1. In such a case, thermal gradient is generated on the waveguide 1 and a diffraction grating 2 by making the heat value generated by the means 5a different from the heat value generated by the means 5b. Since the refraction factor of the waveguide 1 is a function of temperature, the equivalent refraction factor Neff of the grating 2 also becomes a function of temperature. Thermal gradient applied by the means 5a and 5b is led to a distribution of a waveguide longitudinal direction to the factor Neff, too. Then, an effect being the same as a chirped grating is generated by the thermal gradient, and when wavelength is different, a distance to a reflection point is different to generate dispersion. Dispersion quantity to be generated is changed by changing thermal gradient applied to the grating 2 in this way. |
