Thin-Film Lithium Modulator Waveguide for Tight Low-Loss Bends
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Solution Overview
Problem
Existing thin-film lithium niobate and lithium tantalate electro-optic modulators require substantial bends, which limit the integration density due to large bending radii and increased optical losses, hindering the development of more compact and efficient photonics devices.
Innovation Solution
The implementation of tighter bends in photonics devices using thin film lithium-containing materials, such as lithium niobate and lithium tantalate, by omitting portions of the slab in the waveguide's bend region, allowing for bending radii as low as 10 micrometers with optical losses below 0.5 dB for a ninety-degree bend.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional waveguide bends are used in thin-film lithium niobate modulators, then velocity matching between optical and microwave signals is achieved, but the bending radius must be large (greater than 50 micrometers) resulting in increased device area and reduced integration density
Solution Approach 1:
The patent changes the physical parameters of the waveguide in the bend region by modifying the slab thickness. By reducing the slab thickness in the bend region compared to the ridge region, the effective index of the optical mode is reduced, allowing for tighter bending radii while maintaining velocity matching between optical and microwave signals. This parameter change enables bending radii as small as 10 micrometers while achieving the same velocity matching effect that traditionally required bending radii greater than 50 micrometers.
2Reliability
If larger bending radii are used to reduce optical losses, then optical signal integrity is maintained, but the device area increases significantly (at least two hundred micrometers for four ninety degree bends)
Solution Approach 1:
The patent modifies the slab thickness parameter in the bend region to reduce the effective index and enable tighter bends. By carefully controlling the slab thickness reduction, the patent achieves bending radii as small as 10 micrometers while keeping optical losses below 0.5 dB for ninety-degree bends. This approach maintains optical signal integrity without requiring the traditional large bending radii that would consume at least two hundred micrometers of device area.
3Productivity
If tighter bends are implemented to reduce device area, then integration density is improved, but optical losses increase significantly
Solution Approach 1:
The patent changes the slab thickness parameter in the bend region to enable tighter bends while controlling optical losses. By reducing the slab thickness, the effective index is reduced, which allows for smaller bending radii. The patent optimizes this parameter change to achieve bending radii as small as 10 micrometers while maintaining optical losses below 0.5 dB for ninety-degree bends, thus improving integration density without excessive optical loss.
Solution Approach 2:
The patent applies local quality by creating a non-uniform slab thickness profile where the slab is thinner in the bend region compared to the ridge region. This local modification of the waveguide structure allows the bend region to have different optical properties (lower effective index) suitable for tight bending, while the ridge region maintains its original properties for low-loss propagation. This localized structural change enables tighter bends with controlled optical losses.
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
This approach enables more compact photonics devices with improved integration density and reduced optical losses, facilitating efficient modulation and velocity matching of optical and electrode signals.
Implementation Method 1
electro-optic modulators include electrodes carrying electric signal(s) that modulate the optical signal (e.g., through the electro-optic effect)
Data Source
AI summary
A photonics device is described. The photonics devices include at least one electrode and a waveguide. The waveguide includes electro-optic material(s), a ridge, and a slab. A first portion of the waveguide is proximate to the electrode(s), while a second portion of the waveguide includes a bend. The ridge includes a first side and a second side opposite to the first side. Portions of the slab are proximate to the first side and the second side of the ridge in the first portion of the waveguide. A portion of the slab is omitted in the second portion of the waveguide.