Abstract: Conventional dispersion compensators were not sufficient to satisfy a demand to set a different dispersion value for each WDM wavelength in a ring-mesh type network that utilizes wavelength selective switches or the like. The devices were insufficiently reduced in size and power consumption and used with difficulty to change dispersion characteristics for each wavelength flexibly in a simple manner. A dispersion compensator of the present invention uses general-purpose optical components including a spatial light modulator for providing discrete phases to set appropriately the relationship between the focusing beam radius and the spatial light modulator pixel, thereby providing various dispersion compensation characteristics.

Abstract: An object of the present invention is to provide a wavelength blocker having the function of adjusting or cutting off the light intensity of a wavelength division multiplexed (WDM) optical signal of a given wavelength. The wavelength blocker provided by the present invention has the following features. Specifically, the wavelength blocker has a structure configured to cut off light of any diffraction order other than required diffraction order, contained in an optical signal diffracted by an arrayed waveguide grating that demultiplexes a wavelength, and thus, the wavelength blocker has crosstalk characteristics or an extinction ratio superior to those of a conventional wavelength blocker and thus has optimum packaging design. Further, the wavelength blocker can become smaller in size than the conventional wavelength blocker, and enables achieving polarization independence and cost reduction.

Abstract: Cores of an optical waveguide forming a Y-branch structured thermo-optic switch are stacked in a direction perpendicular to a substrate, and a heater is disposed on a clad right above an area where the cores overlap, thereby utilizing a large temperature gradient by the heater in the direction perpendicular to the substrate. The resulting stacked thermo-optic switch is low in power consumption and signal loss and high in extinction ratio.

Abstract: In a digital thermo-optic switch and an optical ADM filter of the present invention, functional components such as a splitter and a grating structure part formed in the course of an optical circuit as a component are composed of silicone materials which are superior in heat resistance, reduced loss, and low birefringence, thereby achieving sufficiently practical thermal stability, low loss at 1.55 to 1.58 .mu.m band, wavelength selectivity, and cost reduction.