Multimode Interference Based VPIN Diode Waveguides

A variable optical attenuator comprising a vertical p-i-n diode waveguide, the variable optical attenuator comprising:

• a waveguide portion adapted for propagating a multimode wave comprising an intrinsic semiconductor region for the vertical p-i-n diode;
• a first contact and a second contact for electrically contacting a first electrode and a second electrode of the vertical p-i-n diode;
• an input section for coupling radiation into the waveguide portion;
• and
• an output section for coupling radiation out of the waveguide portion,
• wherein the input section, the output section, and the waveguide portion are configured to support a multimode interference pattern for the multimode wave with an optical field with a lateral inhomogeneous spatial distribution in the waveguide portion comprising regions with higher optical field intensity and regions with lower optical field intensity, and
• wherein the second contact physically contacts the second electrode in at least one region of the waveguide with lower optical field intensity.

A method for manufacturing an integrated electro-optical semiconductor device comprising a vertical p-i-n diode waveguide, the device comprising a waveguide portion adapted for propagating a multimode wave, the waveguide portion comprising an intrinsic semiconductor region of the vertical p-i-n diode, the method comprising:

• providing a first electrode in a pattern on a substrate, the first electrode being doped with charge carriers of a first polarity;
• providing an intrinsic semiconductor region on the first electrode,
• providing a second electrode on the intrinsic semiconductor region, the second electrode being doped with charge carriers of an opposite polarity;
• providing an input section for coupling radiation into the waveguide portion and an output section for coupling radiation out of the waveguide portion;
• forming a first contact for electrically contacting the first electrode of the vertical p-i-n diode;
• and
• forming a second contact for electrically contacting the second electrode of the vertical p-i-n diode,
• wherein the waveguide portion comprises at least part of the intrinsic semiconductor region of the vertical p-i-n diode, and
• wherein the input section, the output section, and the waveguide portion of the vertical p-i-n diode are configured for supporting a multimode interference pattern for the multimode wave with an optical field with a lateral inhomogeneous spatial distribution in the waveguide portion comprising regions with higher optical field intensity and regions with lower optical field intensity, the second contact physically contacting the second electrode in at least one region of the waveguide with lower optical field intensity.