Patent ID: 7215491

Claim:
An optical path switching device, comprising: a light absorption layer film arranged such that at least a control light focuses on the light absorption layer film; means for converging and irradiating on the light absorption layer film each of a control light having a wavelength selected from a wavelength band which is absorbed by the light absorption layer film and a signal light having a wavelength selected from a wavelength band which is not absorbed by the light absorption layer film; a thermal lens forming element including the light absorption layer film, wherein a thermal lens is reversibly formed according to a distribution of refraction index created by a temperature increase generated in and around an area of the light absorption layer film in which the control light is absorbed, such that, according to whether or not the control light is irradiated, the converged signal light is output either as is in its converged form or after its spread angle is changed; and a mirror including a hole and reflecting means, wherein, according to whether or not the control light is irradiated, the signal light output from the thermal lens forming element is either passed through the hole or reflected by the reflecting means to change the optical path.