Optical waveguide modulator communications device and method of modulating light using same

A method of modulating light using an optical modulator comprising a substrate, a first waveguide layer formed on said substrate, a second waveguide layer stacked together with said first waveguide layer in a direction of a thickness thereof on said substrate, said second waveguide layer having a waveguide mode different from that of said first waveguide layer, a diffraction grating formed in a region where the waveguide modes of said first and second waveguide layers overlap each other, and an electrode, comprising the steps of:

• inputting light into said first waveguide layer;
• causing the input light to propagate through said first waveguide layer;
• causing said diffraction grating to couple to said second waveguide layer light having a wavelength range selected from those of light components propagating through said first waveguide layer;
• applying a modulated electrical signal through said electrode to change the wavelength of the light coupled by said diffraction grating, so that the light propagating through said first waveguide layer is modulated by the change in wavelength;
• and
• outputting the modulated light from said first waveguide layer.

An optical modulator comprising:

• a substrate;
• a first cladding layer consisting essentially of a semiconductor of a first conductivity type formed on said substrate;
• a first waveguide layer consisting essentially of a semiconductor of the first conductivity type formed on said first cladding layer, said first waveguide layer being arranged to guide external input light and output modulated light;
• a second cladding layer consisting essentially of a semiconductor of the first conductivity type formed on said first waveguide layer;
• a second waveguide layer consisting essentially of an intrinsic semiconductor of a quantum well structure formed on said second cladding layer, said second waveguide layer having a waveguide mode different from that of said first waveguide layer;
• a third cladding layer consisting essentially of a semiconductor of a second conductivity type formed on said second waveguide layer;
• a diffraction grating formed in a region where the waveguide modes of said first and second waveguide layers overlap each other, said diffraction grating coupling to said second waveguide layer light having a wavelength range selected from those of light components propagating through said first waveguide layer;
• and
• an electrode for applying a reverse-biasing modulated electrode filed to said first and second waveguide layers and said first, second, and third cladding layers,
• wherein when the electric field is applied through said electrode, the wavelength of the light coupled by said diffraction grating is changed to modulate the light output from said first waveguide layer.

A method of modulating light by using an optical modulator comprising a substrate, a first cladding layer consisting essentially of a semiconductor of a first conductivity type formed on said substrate, a first waveguide layer consisting essentially of a semiconductor of the first conductivity type formed on said first cladding layer, a second cladding layer consisting essentially of a semiconductor of the first conductivity type formed on said first waveguide layer, a second waveguide layer consisting essentially of an intrinsic semiconductor of a quantum well structure formed on said second cladding layer, said second waveguide layer having a waveguide mode different from that of said first waveguide layer, a third cladding layer consisting essentially of a semiconductor of a second conductivity type formed on said second waveguide layer, a diffraction grating formed in a region where the waveguide modes of said first and second waveguide layers overlap each other, and an electrode, comprising the steps of:

• inputting light into said first waveguide layer;
• causing the input light to propagate through said first waveguide layer;
• causing a diffraction grating to couple to said second waveguide layer light having a wavelength range selected from those of light components propagating through said first waveguide layer;
• applying a reverse-biasing modulated electrical signal to said first and second waveguide layers and said first, second, and third cladding layers through said electrode to change the wavelength of the light coupled by said diffraction grating, so that the light propagating through said first waveguide layer is modulated by the change in wavelength;
• and
• outputting the modulated light from said first waveguide layer.