Adiabatic Reflective Loopback for Compact Low-Confinement Waveguides
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Implementing a loopback structure in photonic integrated circuits using low-confinement waveguides is challenging due to the need for a large area to change direction slowly and the difficulty in designing a reflector that avoids excess losses from diffraction and other effects.
Innovation Solution
A reflective loopback structure is designed with adiabatic transitions in curvature and width, using ridge waveguides that gradually guide light to a reflector, featuring angled sections and a merged waveguide structure to minimize diffraction and reduce area requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If low-confinement waveguides are used to change direction, then optical losses are reduced, but the area required for the loopback structure increases prohibitively
Solution Approach 1:
The waveguides are designed with curved geometries instead of sharp bends, using adiabatic curvature transitions to guide light around the reflector. The curved waveguide paths allow gradual direction changes that maintain low optical losses while fitting within a compact area, resolving the contradiction between loss reduction and area minimization.
Solution Approach 2:
The waveguide width is varied along the propagation direction, transitioning from a first width at the input to a second width at the output. This parameter change enables adiabatic transitions that maintain mode confinement and reduce losses while allowing the waveguides to navigate the compact loopback geometry, simultaneously achieving low losses and small area.
2Area of stationary object
If a reflector is used to reverse light direction in a small area, then the loopback area is reduced, but excess losses occur due to diffraction and other effects
Solution Approach 1:
The waveguide width is adjusted in advance before the light reaches the reflector, creating an adiabatic transition that prepares the optical mode for reflection. This preliminary width modification reduces diffraction effects at the reflector interface, minimizing excess losses while maintaining the compact area provided by the reflector geometry.
Solution Approach 2:
The adiabatic width transition acts as an intermediary between the straight waveguide section and the reflected section, gradually transforming the optical mode to reduce abrupt discontinuities. This intermediate transition region minimizes diffraction and scattering losses at the waveguide-reflector interface, allowing compact area utilization without excessive 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
The solution effectively reverses light direction in a compact form, reducing optical losses and minimizing the area consumed by the loopback structure in photonic integrated circuits.
Implementation Method 1
a reflector reversing a direction of light between the first ridge waveguide and the second ridge waveguide
Implementation Method 2
a design of a reflector that avoids excess losses due to diffraction and other effects
Data Source
AI summary
In part, the disclosure relates to a reflective loopback structure comprising a reflector, a first waveguide defining an optical input, a second waveguide defining an optical output; and a merged waveguide structure defining a front surface and a back surface and a first axis. In some embodiments, the reflector disposed at a back surface, the first axis normal to the front surface and the back surface, and the first waveguide and the second waveguide angled relative to each other by an angle θ defined therebetween. In many embodiments, the waveguides extend from the front surface in different directions and each angled relative to the first axis by an angle φ, wherein φ is about θ/2, the optical input in optical communication with the optical output, the reflector in optical communication with the first optical input and the first optical output.