Optical Modulator Depletion Region Design for Loss Reduction
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Solution Overview
Problem
Optical modulators often exhibit high optical loss due to the structures used to apply reverse bias, which affects their performance in communications applications.
Innovation Solution
The optical device features a light-transmitting medium with a slab region and a ridge, where a depletion region forms between n-type and p-type doped regions, allowing for bias application through an electrical pathway in the slab region, avoiding direct contact on the ridge and thus minimizing optical loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal contacts or highly doped materials are used to apply reverse bias to the waveguide, then the electrical connection is improved, but optical loss increases
Solution Approach 1:
The patent extracts the metal contacts and highly doped materials from the waveguide structure, eliminating the source of optical loss while maintaining electrical connection functionality through alternative means
Solution Approach 2:
The patent introduces an intermediary approach by using the depletion region itself as the electrical connection medium, allowing reverse bias application without direct metal contact on the waveguide, thereby reducing optical loss
2Reliability
If the depletion region size is increased to improve modulation performance, then the modulation depth is improved, but the optical loss increases
Solution Approach 1:
The patent applies local quality by creating a non-uniform doping distribution where highly doped regions are positioned away from the optical mode path, allowing large depletion regions for good modulation performance while minimizing optical loss in the light-transmitting regions
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 design reduces optical loss by eliminating the need for metal contacts or highly doped materials on the waveguide, enhancing modulation speed and efficiency while maintaining control over the depletion region's size and shape.
Implementation Method 1
The depletion region has a different index of refraction than the surrounding light-transmitting region. As a result, changing the size of the depletion region changes the speed at which the light signal travels through the waveguide.
Implementation Method 2
The modulator is tuned by applying a reverse bias to the modulator. The reverse bias changes the size of the depletion region.
Implementation Method 3
these phase modulators often include a waveguide that has an n-type doped region and a p-type doped region positioned such that a depletion region is formed in the waveguide
Data Source
AI summary
An optical device includes a light-transmitting medium positioned on a base. The light-transmitting medium includes a slab region and a ridge extending upward from the slab region. The ridge defines a portion of an optical waveguide on the device. A modulator is also positioned on the base. The modulator includes a first doped region of the light-transmitting medium and a second doped region of the light-transmitting medium. The first doped region and the second doped region are configured such that a depletion region forms in the waveguide when an electrical bias is not applied to the modulator. At least a portion of the first doped region is positioned in the ridge and at least a portion of the second doped region is positioned in the slab region. The light-transmitting medium includes a first electrical pathway extending from a first location to the first doped region. The first location is on top of the light-transmitting medium and is spaced apart from the ridge.