PIC Coupling With Focusing Mirrors and Optical Isolation
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Solution Overview
Problem
Efficient and cost-effective alignment of optics to couple light into and out of photonic integrated circuits (PICs) is challenging, with existing methods being expensive and resulting in low yield.
Innovation Solution
Fabricating focusing mirrors on the PIC die to reflect light towards curved mirrors for collimation and using an optical isolator below the die to prevent reflected light from reentering the waveguides, with optional compensator blocks or hole configurations to allow light transmission without blocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If V-grooves are used to align fiber connector or lens is fabricated on PIC, then light coupling efficiency is improved, but manufacturing cost increases and yield decreases
Solution Approach 1:
The patent extracts the optical alignment function from complex fabrication structures (V-grooves, integrated lenses) and implements it through a separate, easily manufacturable lens array component that can be coupled to the PIC using simple, low-cost processes. This separates the precision optical function from the PIC fabrication process itself.
Solution Approach 2:
The patent introduces a lens array as an intermediary component between the fiber connector and the PIC waveguides. This lens array serves as a mediator that provides the necessary optical focusing and alignment without requiring complex integration into the PIC structure, thereby simplifying manufacturing while maintaining coupling efficiency.
2Object-affected harmful factors
If optical isolator is positioned below PIC die, then back reflections are prevented, but alignment complexity increases
Solution Approach 1:
The patent merges the optical isolator with the existing lens array structure, positioning the isolator below the PIC die in close proximity to the lenses. This integration allows the isolator to benefit from the same alignment tolerances and mechanical support structure already established for the lens array, thereby preventing back reflections without significantly increasing alignment complexity.
Solution Approach 2:
The patent positions the optical isolator in a different spatial dimension (below the PIC die, perpendicular to the main optical path) rather than in-line with the horizontal optical path. This vertical positioning allows the isolator to intercept back-reflected light without interfering with the primary light coupling path, simplifying the alignment requirements.
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
Facilitates efficient coupling of light into and out of PICs while preventing back reflections, enhancing yield and reducing costs by optimizing alignment and integration processes.
Implementation Method 1
The curved mirrors are to collimate the beams and direct them out of the PIC die through the bottom surface
Implementation Method 2
an optical isolator is positioned below the bottom of the PIC die to prevent any reflected light from reentering the waveguides
Data Source
AI summary
Technologies for coupling to and from a photonic integrated circuit (PIC) with an optical isolator are disclosed. In one embodiment, light beams from waveguides on a PIC die are reflected towards flat mirrors on the bottom surface of the PIC die. The flat mirrors reflect the light towards curved mirrors defined in a top surface of the PIC die, which collimate the beam and direct the collimated beams out the bottom surface of the PIC die. An optical isolator below the PIC die can allow the beams to pass while blocking beams in the opposite direction.