Optical bandpass filter having a variable passband wavelength

An optical bandpass filter supplied with an incident optical beam including therein a plurality of optical components with respective wavelengths that differ from each other, for selectively passing a specified optical component having a specified wavelength, comprising:

• a waveguide region having upper and lower major surfaces and extending from an input end to an output end for guiding the optical beam supplied to said input end, from said input end to said output end;
• a clad structure provided above and below &he waveguide region for confining the optical beam in said waveguide region;
• a plurality of quantum well boxes formed in the waveguide region with respectively different quantum levels, said quantum well boxes comprising a material having a first band gap and defined by a boundary for all of the three-dimensional directions, said quantum well boxes having a variety of sizes in at least one of said three-dimensional directions, for selectively absorbing the optical components in the incident optical beam that causes a resonance with the quantum level of the quantum well box;
• a barrier region provided in said waveguide region for surrounding each of the plurality of quantum well boxes with respect to all of three-dimensional directions, said barrier region comprising a material having a second band gap that is substantially larger than said first band gap;
• and
• window means provided on the clad structure for directing a control optical beam such that the control optical beam irradiates the plurality of quantum well boxes.