Optical mach-zehnder interferometers with low polarization dependence
AssigneeLightwave Microsystems Corporation
InventorsAlice Liu, Kenneth McGreer, Wenjie Chen, Wayne Wai Wing Lui
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Abstract
This relates generally to optical waveguide-based devices including dynamically programmable optical attenuators. In particular, this provides an optical attenuator having a Mach Zehnder configuration with reduced polarization dependence. The devices herein facilitate the implementation of continuously-variable optical attenuators, optical shutters, and optical switches in an integrated photonic circuit.
Claims21
An optical device having a Mach-Zehnder, the device comprising:
- a first optical waveguide and a second optical waveguide, each optical waveguide having an input port and output port;
- a first optical coupling region wherein a portion of said first waveguide and a portion of said second waveguide are positioned adjacent to one another to provide optical coupling between said portions of said waveguides, a length of said waveguides within said coupling region, a width of each respective waveguide within said coupling region, and a separation between said waveguides within said coupling region defining a first coupler balance;
- a second optical coupling region wherein a portion of said first waveguide and a portion of said second waveguide are positioned adjacent to one another to provide optical coupling between said portions of said waveguides, a length of said waveguide within said coupling region, a width of each respective waveguide within said coupling region, and a separation between said waveguides within said coupling region defining a second coupler balance;
- an active region between said first coupling region and said second coupling region wherein in said active region said first waveguide and said second waveguide each comprise a first and second arm, said waveguides are positioned adjacent to one another to provide substantially no optical coupling between said portions of said waveguides, a portion of one of said first waveguides in said active region defines an optical path length of a first arm and a portion of said second waveguide in said active region comprises an optical path of the second arm;
- wherein said optical path length of the first arm and said optical path length of the second arm are unequal;
- and
- wherein the coupler balance of at least one of the coupling regions is substantially non-zero in value.
A method for reducing polarization dependent loss in a variable optical attenuator device having a Mach-Zehnder configuration, where said variable optical attenuator includes a first and second optical waveguide for transmitting an optical signal in each respective waveguide, at least one coupling region, and a phase shifting region between said coupling region, the method comprising:
- configuring at least one coupling region to have a non-zero coupler balance;
- and
- selecting an optical path length difference between the first waveguide and the second waveguide to induce a non-zero phase difference between optical signals.
Dependencies are inferred from the claim text.