Optical Semiconductor Device With Narrower Waveguide Mesa

Solution Overview

Problem

In optical semiconductor devices where an optical waveguide is butt-joined to a semiconductor laser, light scattering occurs at the joining portion due to different layer structures, leading to reduced optical output and inefficient coupling to optical fibers.

Innovation Solution

The optical semiconductor device features a mesa structure for both the optical semiconductor element and the optical waveguide, with the waveguide's mesa width being narrower than the element's, and includes buried layers and constricted or dent portions to minimize light scattering and mode disturbance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the optical waveguide layer is butt-joined to the active layer with different layer structures, then the device can be manufactured with standard processes, but light scatters at the joining portion and leaks to the outside, reducing optical output

Engineering Contradiction:

Improvestandard manufacturing processVSAvoidoptical output

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent applies local quality by creating a mesa structure with a narrower width in the optical waveguide region compared to the active layer region. This localized structural modification at the joining portion reduces light scattering and mode disturbance without requiring changes to the overall manufacturing process, thus maintaining ease of manufacture while improving optical output

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the geometric parameter of the mesa width, making it narrower in the optical waveguide layer than in the active layer. This parameter change reduces the mode field diameter mismatch at the joining interface, minimizing light scattering and leakage, thereby reducing energy loss while maintaining compatibility with standard manufacturing processes

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If the optical waveguide layer is butt-joined to the active layer with different layer structures, then the device structure can be simplified, but the light mode scatters and does not efficiently join to optical fibers

Engineering Contradiction:

ImprovestructureVSAvoidcoupling efficiency to optical fibers

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by creating a mesa structure with a narrower width in the optical waveguide region compared to the active layer region. This localized structural modification at the joining portion reduces light scattering and mode disturbance without requiring changes to the overall manufacturing process, thus maintaining ease of manufacture while improving optical output

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the geometric parameter of the mesa width, making it narrower in the optical waveguide layer than in the active layer. This parameter change reduces the mode field diameter mismatch at the joining interface, minimizing light scattering and leakage, thereby reducing energy loss while maintaining compatibility with standard manufacturing processes

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8792756B2Optical semiconductor device

Publication Date: 2014.07.29 MITSUBISHI ELECTRIC CORP

AI summary

An optical semiconductor device includes an optical semiconductor element and an optical waveguide butt-joined to the optical semiconductor element. The optical semiconductor element has a mesa structure including an active layer and a burying layer coating side faces of the active layer. The optical waveguide has a mesa structure including an optical waveguide layer having a layer structure different from the active layer, and a burying layer coating side faces of the optical waveguide layer. Mesa width of the optical waveguide is narrower than mesa width of the optical semiconductor element.