Tunable Optomechanical Apparatus Using Optical Gradient Forces
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Solution Overview
Problem
Current methods for tuning optical microcavities, such as electro-optic and thermo-optic tuning, are limited in bandwidth and require high temperatures or suffer from material constraints, while mechanical tuning using optical forces offers only sub-nanometer tuning ranges.
Innovation Solution
A tunable optomechanical apparatus comprising two coupled optical microring resonators with a sub-wavelength air gap, allowing evanescent coupling and optical gradient force-induced tuning, enabling broadband frequency tuning across the C and L telecommunications bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electro-optic tuning is used, then tuning is achieved, but tuning range is limited to sub-nanometer
Solution Approach 1:
The patent replaces traditional electro-optic or thermo-optic tuning mechanisms with an optomechanical system that uses optical gradient forces to mechanically actuate the microring resonator. This substitution enables large-scale tuning (exceeding 30 nm) by directly manipulating the physical position of the resonator rather than relying on limited material property changes, thereby achieving both precise control and extended tuning range across the C and L telecommunications bands.
2Manufacturing precision
If thermo-optic tuning is used, then tuning range increases to tens of nm, but high temperatures (>400° K) are required
Solution Approach 1:
The patent substitutes thermo-optic tuning with optomechanical actuation using optical gradient forces. This eliminates the need for high temperatures by using radiation pressure and gradient forces from circulating photons to physically move the microring resonator. The system achieves tens of nanometers to over 30 nm tuning range at normal operating temperatures, avoiding thermal management complexities and material constraints associated with high-temperature operation.
3Manufacturing precision
If free-carrier injection tuning is used, then tuning range increases to tens of nm, but free-carrier induced losses occur
Solution Approach 1:
The patent replaces free-carrier injection with optomechanical tuning using optical gradient forces. This substitution eliminates free-carrier induced losses by avoiding the injection of charge carriers into the resonator material. Instead, the system uses the momentum and gradient forces of optical fields to mechanically actuate the resonator, achieving comparable or superior tuning range (over 30 nm) without the penalty of increased insertion loss or reduced quality factor.
4Ease of operation
If optical gradient forces are used for mechanical actuation, then tuning is achieved, but tuning range is limited to 2 nm
Solution Approach 1:
The patent enhances the tuning range of optical gradient force actuation by introducing a lever-arm mechanism through a cantilever structure. The microring resonator is suspended on a cantilever that amplifies small optical gradient forces into larger mechanical displacements. This dimensional leverage transforms sub-2 nm direct actuation into over 30 nm effective tuning range, maintaining the advantages of optical force actuation while dramatically extending the achievable tuning bandwidth across C and L bands.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Achieves efficient, broadband optomechanical tuning exceeding 30 nm with low optical power, outperforming existing methods in bandwidth and simplicity of fabrication, while minimizing thermal and Kerr effects.
Implementation Method 1
an input signal waveguide disposed adjacent a periphery of the resonator component in a manner that allows evanescent coupling of light from the input signal waveguide into a resonant cavity of the resonator component
Implementation Method 2
evanescently coupling the input optical signal into the resonator component cavity by suitably changing the air gap dimension using a radiative force from a control signal evanescently coupled into the resonator component
Data Source
AI summary
A broadly tunable optomechanical apparatus includes a resonator component consisting of two coupled optical microring resonators disposed in a stacked relationship, an input waveguide disposed adjacent a periphery of the resonator component, and a control signal waveguide coupled to the resonator component or the input signal waveguide. A broadband optical switch includes a plurality of resonator components each of which corresponds to a selected signal wavelength, predetermined by the geometry and design of the resonator component, and a respective plurality of output signal waveguides, and a respective plurality of a control signal waveguides each coupled to a respective resonator component. Associated tuning and switching methods and applications are disclosed.