Apparatus, systems, and methods for on-chip spectroscopy using optical switches

A method of spectroscopy, the method comprising:

• splitting incident light into a first portion and a second portion;
• coupling the first portion of the incident light into a first interference arm, the first interference arm including:
• first optical switches;
• first variable waveguides and first reference waveguides, wherein an optical path length of each first variable waveguide is longer than an optical path length of its corresponding first reference waveguide,
• the coupling including coupling the first portion of the incident light into each first variable waveguide when its corresponding first optical switch is in a first state,
• the coupling further including coupling the first portion of the incident light into each first reference waveguide when its corresponding first optical switch is in a second state;
• coupling the second portion of the incident light into a second interference arm, the second interference arm including:
• second optical switches;
• second variable waveguides and second reference waveguides, wherein an optical path length of each second variable waveguide is shorter than an optical path length of its corresponding second reference waveguide,
• the coupling including coupling the second portion of the incident light into each second variable waveguide when its corresponding second optical switch is in a first state,
• the coupling further including coupling the second portion of the incident light into each second reference waveguide when its corresponding second optical switch is in a second state;
• actuating the first optical switches to couple the first portion of the incident light through at least one of the first variable waveguides, or at least one of the first reference waveguides, or combinations thereof;
• actuating the second optical switches to couple the second portion of the incident light through at least one of the second variable waveguides, or at least one of the second reference waveguides, or combinations thereof;
• and
• detecting interference between the first portion of the incident light from the first interference arm and the second portion of the incident light from the second interference arm.

A spectrometer, comprising:

• a beam splitter to split incident light into a first portion and a second portion;
• a first interference arm, in optical communication with the beam splitter, to receive the first portion of the incident light, the first interference arm comprising:
• first optical switches, each first optical switch switchable between a first state and a second state;
• first variable waveguides and first reference waveguides, wherein each first optical switch is coupled to a corresponding first variable waveguide and a corresponding first reference waveguide, each first variable waveguide to receive the first portion of the incident light when its corresponding first optical switch is in its first state, each first reference waveguide to receive the first portion of the incident light when its corresponding first optical switch is in its second state, wherein the first variable waveguides have identical optical path lengths and the first reference waveguides have different optical path lengths;
• a second interference arm, in optical communication with the beam splitter, to receive the second portion of the incident light, the second interference arm comprising:
• second optical switches, each second optical switch switchable between a first state and a second state;
• second variable waveguides and second reference waveguides, wherein each second optical switch is coupled to a corresponding second variable waveguide and a corresponding second reference waveguide, each second variable waveguide to receive the second portion of the incident light when its corresponding second optical switch is in its first state, each second reference waveguide to receive the second portion of the incident light when its corresponding second optical switch is in its second state, wherein each second reference waveguide has an optical path length identical to the optical path length of the corresponding first reference waveguide;
• and
• a detector in optical communication with the first interference arm and the second interference arm, to detect interference of the first portion of the incident light from the first interference arm and the second portion of the incident light from the second interference arm.

A method for spectroscopy, comprising:

• splitting incident light into a first portion and a second portion;
• coupling the first portion of the incident light into a first interference arm, the first interference arm comprising:
• first optical switches;
• first variable waveguides and first reference waveguides, wherein the first variable waveguides have identical optical path lengths and the first reference waveguides have different optical path lengths,
• the coupling including coupling the first portion of the incident light into each first variable waveguide when its corresponding first optical switch is in a first state,
• the coupling further including coupling the first portion of the incident light into each first reference waveguide when its corresponding first optical switch is in a second state;
• coupling the second portion of the incident light into a second interference arm, the second interference arm comprising:
• second optical switches;
• second variable waveguides and second reference waveguides, wherein each second reference waveguide has an optical path length identical to the optical path length of the corresponding first reference waveguide,
• the coupling including coupling the second portion of the incident light into each second variable waveguide when its corresponding second optical switch is in a first state,
• the coupling further including coupling the second portion of the incident light into each second reference waveguide when its corresponding second optical switch is in a second state;
• and
• actuating the first optical switches to couple the first portion of the incident light through at least one of the first variable waveguides, or at least one of the first reference waveguides, or combinations thereof;
• actuating the second optical switches to couple the second portion of the incident light through at least one of the second variable waveguides, or at least one of the second reference waveguides, or combinations thereof;
• and
• detecting interference between the first portion of the incident light from the first interference arm and the second portion of the incident light from the second interference arm.