Grating Couplers for TM Polarized Light in Silicon Photonics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Silicon photonics face challenges in efficiently coupling transverse-magnetic (TM) polarized light into and out of photonic chips due to high optical losses in standard TM couplers, which often require additional polarization rotators, introducing excess losses and reducing the link power budget.
Innovation Solution
An optical coupler system that includes a polarizing beam splitter and grating couplers for TE and TM polarizations, allowing efficient coupling of light into photonic chips without the need for additional polarization rotators by orienting light beams to match the fundamental waveguide mode, thereby minimizing losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If standard TM couplers are used to couple TM polarized light into photonic chips, then coupling is achieved, but high optical losses occur
Solution Approach 1:
The coupling apparatus segments the coupling process by separating TE and TM polarization paths using a polarizing beam splitter, with dedicated grating couplers for each polarization type. This segmentation allows each grating coupler to be optimized for its specific polarization, reducing overall optical losses while maintaining coupling efficiency.
2Adaptability or versatility
If polarization rotators are added to rotate TM polarized light output, then polarization matching is achieved, but excess losses are introduced and link power budget is reduced
Solution Approach 1:
Instead of rotating the polarization of TM light after coupling (the conventional approach), the invention inverts the approach by using a polarizing beam splitter to separate polarizations before coupling, and by designing grating couplers that directly couple TM polarized light without requiring subsequent rotation. This eliminates the need for polarization rotators and their associated losses.
3Manufacturing precision
If additional polarization rotators are introduced to achieve proper polarization orientation, then coupling accuracy is improved, but device complexity increases
Solution Approach 1:
The coupling apparatus achieves multi-functionality by using a polarizing beam splitter that simultaneously handles both TE and TM polarization separation, with each path leading to dedicated grating couplers. This universal approach eliminates the need for separate polarization rotators for each coupling point, reducing device complexity while maintaining high coupling accuracy through optimized grating designs for each polarization type.
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 solution enables efficient coupling of TM polarized light into photonic chips, reducing optical losses and eliminating the need for additional polarization rotators, thus improving signal quality and power budget in optical communication systems.
Implementation Method 1
a grating coupler on the chip. The light beam is reflected onto the grating coupler such that the direction of TM polarization is within the first plane of incidence, and the first beam of light is incident on the first plurality of gratings at an angle with respect to a normal to the plane of the first grating coupler
Implementation Method 2
Document US2010119229 describes a waveguide coupler including a polarization splitter positioned between the optical coupling element and the integrated waveguide circuit, to spatially separate both orthogonal polarizations
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
This disclosure provides systems, methods, and apparatus for a photonic chip. The photonic chip includes one or more electronic components in addition to one or more optical components. An optical coupler can be utilized for coupling external optical fibers or sources with the optical components. The optical coupler can include a beam splitter for splitting an incident light having both trans-electric (TE) and trans-magnetic (TM) polarizations into two beams having only TE and TM polarizations. The light beam with TM polarization is incident on a grating coupler on the chip having a horn section, which includes gratings. The light beam is reflected onto the grating coupler such that the direction of TM polarization is within the first plane of incidence, and the first beam of light is incident on the first plurality of gratings at an angle with respect to a normal to the plane of the first grating coupler.