Optical Receiver Facet Coupling for High-Sensitivity Miniaturization
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Solution Overview
Problem
Existing optical receivers face challenges in achieving both high sensitivity and miniaturization due to limitations in extending the optical path length and requiring precise alignment for optical coupling, which complicates mounting and increases size.
Innovation Solution
An optical receiver design featuring a planar light wave circuit with a spot size converter and a semiconductor substrate having a facet surface for oblique incidence of signal light onto the light-receiving element, extending the optical path length without a lens system, allowing for simplified mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the light-absorbing layer is increased to extend the optical path length, then sensitivity is improved, but response speed deteriorates due to increased carrier traveling time
Solution Approach 1:
The patent introduces a folded-back structure that redirects light laterally through the light-absorbing layer using a reflector, extending the optical path length without increasing layer thickness. This allows sensitivity improvement while maintaining fast response speed by avoiding increased carrier traveling time through thickness enhancement.
2Ease of manufacture
If a two-lens system is used for optical coupling between optical fiber and light-receiving element, then mounting margin is improved, but device size increases due to required space between components
Solution Approach 1:
The patent removes the lens system from the optical coupling configuration, replacing it with direct optical coupling between the optical fiber and light-receiving element. This eliminates the space required for lenses and their mounting, achieving miniaturization while maintaining adequate mounting margin through simplified alignment requirements.
3Volume of moving object
If a one-lens system is used for optical coupling to reduce device size, then device size is reduced, but mounting precision requirements increase significantly
Solution Approach 1:
The patent eliminates the lens component entirely, using direct optical coupling between the optical fiber and light-receiving element. This removes the need for precise lens positioning and alignment, achieving both miniaturization and relaxed mounting precision requirements simultaneously.
4Reliability
If the optical path length in the light-absorbing layer is extended to improve sensitivity, then external quantum efficiency is improved, but device complexity increases
Solution Approach 1:
The patent uses a folded-back structure with a reflector to extend the optical path length laterally through the light-absorbing layer, rather than increasing layer thickness. This achieves improved external quantum efficiency while maintaining simple planar device architecture and avoiding complex three-dimensional structures.
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 design enhances sensitivity and miniaturization by extending the optical path length in the light-absorbing layer while simplifying the mounting process, reducing beam diameter, and improving high-frequency characteristics.
Implementation Method 1
a spot size converter for converting a spot size of signal light incident from an optical fiber
Implementation Method 2
the connecting surface is a facet surface that is in contact with the substrate surface at an acute angle or an obtuse angle so that the signal light emitted from the spot size converter is incident on a light-receiving surface of the full light-receiving element
Implementation Method 3
The photodiode is an element that performs photoelectric exchange by generating electrons and holes under irradiation with light having an energy equal to or higher than the band gap of a semiconductor
Data Source
AI summary
Provided is an optical receiver which can be manufactured by a simple mounting method, and achieves both high sensitivity and miniaturization by extension of an optical path length. An optical receiver according to the present disclosure includes a planar light wave circuit which includes a spot size converter for converting a spot size of signal light incident from an optical fiber; a semiconductor substrate connected to the planar light wave circuit via a connecting surface; and a light-receiving element mounted on a substrate surface of the semiconductor substrate, in which the connecting surface is a facet surface that is in contact with the substrate surface at an acute angle or an obtuse angle so that the signal light emitted from the spot size converter is incident on a light-receiving surface of the full light-receiving element.