Active Glass Interposer Waveguides for PIC Coupling Loss Compensation
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Solution Overview
Problem
Efficiently aligning optics to couple light into and out of photonic integrated circuits (PICs) is challenging due to coupling losses, leading to poor performance and low yield in existing methods such as using V-grooves or fabricating lenses.
Innovation Solution
A glass interposer with signal waveguides and a pump waveguide adjacent to each signal waveguide, where light from a laser pumps ions in the signal waveguides to create a population inversion, amplifying the signal and compensating for coupling losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If V-grooves are used to align fiber connector or lens is fabricated on PIC, then coupling alignment is achieved, but coupling losses occur leading to poor performance
Solution Approach 1:
A glass interposer with waveguides is introduced as an intermediary component between the optical fiber and the PIC. The interposer includes input waveguides that receive light from the fiber and output waveguides that couple to the PIC, with pump waveguides positioned adjacent to signal waveguides to provide optical amplification. This intermediary structure with active amplification compensates for coupling losses that occur in traditional passive alignment methods.
2Productivity
If traditional alignment methods are used, then manufacturing process is simple, but yield is low due to coupling losses
Solution Approach 1:
The glass interposer with signal waveguides and pump waveguides is fabricated in advance with precise waveguide positioning. The pump waveguides are pre-positioned adjacent to signal waveguides, and dopants are pre-implanted in the signal waveguides. This preliminary preparation of the interposer with built-in amplification capability allows compensation for coupling losses to occur automatically during operation, improving yield without requiring complex real-time alignment adjustments.
3Reliability
If pump waveguide is positioned adjacent to signal waveguide, then signal amplification is achieved, but device complexity increases
Solution Approach 1:
The pump waveguide and signal waveguide are merged into a single glass interposer substrate, with the pump waveguide positioned adjacent to the signal waveguide. Both waveguides are fabricated using the same waveguide formation process on the same substrate, and the dopant implantation process treats both waveguides similarly. This merging approach provides signal amplification while avoiding the complexity of separate, independently fabricated waveguide systems.
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
The amplification in the signal waveguides reduces coupling losses from optical fibers to the PIC, improving performance and yield by enhancing signal transmission.
Implementation Method 1
Light from a laser is coupled into the pump waveguides, and the light pumps ions in the signal waveguides to create a population inversion. When signal light passes through the signal waveguides, it is amplified.
Implementation Method 2
the light pumps ions in the signal waveguides to create a population inversion
Data Source
AI summary
Techniques for signal amplification for a photonic integrated circuit (PIC) die are disclosed. In the illustrative embodiment, an optical fiber is coupled to an input signal waveguide in a glass interposer, and an input signal waveguide of a PIC die is coupled to the input signal waveguide of the glass interposer. In order to compensate for any coupling losses, the input signal waveguide of the glass interposer is active, amplifying an input signal. Light in a pump waveguide near the input signal waveguide pumps ions in the input signal waveguide into a population inversion, allowing them to amplify the input signal.