Tunable Optical Source Inspection Waveguide
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Solution Overview
Problem
In tunable optical sources where both a light emitter and a photodetector are disposed on a substrate, the end of the optical waveguide for transmitting light from the emitter to the photodetector is not formed at the end surface of the substrate, making it difficult to inspect the photodetector during shipping or other processes.
Innovation Solution
A tunable optical source configuration that includes a substrate with a light source, a wavelength selecting element, a wavelength filter with multiple output ports, a photodetector, and an inspection waveguide connected to the photodetector, allowing inspection light to be input through the inspection waveguide for easier photodetector inspection without relying on light from the light source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If both light emitter and photodetector are disposed on substrate, then integration is improved, but photodetector inspection becomes difficult
Solution Approach 1:
The optical waveguide is segmented into two separate paths: a first optical waveguide for transmitting light from the light emitter to the photodetector, and a second optical waveguide for inputting inspection light to the photodetector. This segmentation allows the inspection function to be independent from the light transmission function, enabling easy photodetector inspection while maintaining integration on a single substrate.
Solution Approach 2:
The second optical waveguide serves a dual purpose: it enables inspection light to reach the photodetector for quality control, and its presence on the substrate maintains the integrated structure. This multi-functionality approach allows the same substrate to support both operational and inspection functions.
2Device complexity
If optical waveguide end is not formed at substrate end surface, then integration is improved, but light input for inspection becomes difficult
Solution Approach 1:
The second optical waveguide is configured to extend to the end surface of the substrate, providing a new dimensional access point for inspection light. This allows inspection light to be input from the substrate's end surface rather than requiring access from the side where the photodetector is located, solving the alignment problem while maintaining integration.
Solution Approach 2:
The second optical waveguide acts as an intermediary element that bridges the inspection light source (external to the substrate) and the photodetector (on the substrate). It provides a dedicated pathway for inspection light to reach the photodetector without interfering with the primary light transmission path, enabling easy inspection while maintaining the integrated structure.
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 easier inspection of the photodetector by providing a dedicated path for inspection light, improving inspection efficiency and reducing the risk of misalignment and yield loss associated with light source alignment.
Implementation Method 1
a wavelength filter disposed on the substrate which includes multiple output ports and which is configured to receive a part of the output light and to output light beams to the respective output ports
Implementation Method 2
a photodetector disposed on the substrate so as to receive the light beam output from one of the plurality of output ports
Data Source
AI summary
A tunable optical source includes a substrate, a light source disposed on the substrate, and a wavelength selecting element configured to select light of a specific wavelength as output light, from light emitted from the light source, in accordance with a control signal. On the substrate, a wavelength filter including multiple output ports and a photodetector are disposed. The wavelength filter is configured to receive a part of the output light and to output light beams to the respective output ports. The photodetector is configured to receive the light beam output from one of the output ports. The tunable optical source further includes an inspection waveguide connecting to the photodetector at one end, and an inspection light input unit for inputting inspection light provided at the other end of the inspection waveguide.