Combined Gain-SOA Chip Monolithic Integration
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Solution Overview
Problem
Conventional hybrid integrated tunable lasers with small line widths often have low optical output power, requiring complex and costly precise coupling of separate amplifiers, which increases manufacturing costs and introduces optical coupling losses.
Innovation Solution
A hybrid laser with a combined Gain-SOA Chip, where the gain section and SOA section are monolithically integrated with an active DFB grating, allowing direct optical coupling within a single chip, reducing manufacturing costs and eliminating free-beam transmission losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a separate EDFA or SOA is coupled downstream to increase optical power, then the optical output power is improved, but the device complexity and manufacturing cost increase due to complicated and precise coupling requirements
Solution Approach 1:
The patent combines the gain section and SOA section into a single monolithically integrated chip. The gain section and SOA section are fabricated together on the same semiconductor substrate with direct optical coupling between them, eliminating the need for separate components and complex external coupling arrangements. This integration directly resolves the contradiction by achieving high optical power while simplifying the device structure and reducing manufacturing complexity.
2Power
If a deeply etched gap mirror is used to integrate SOA on the gain chip, then the optical power is improved, but the manufacturing precision requirements increase due to the need for very narrow gaps
Solution Approach 1:
The patent removes the deeply etched gap mirror structure entirely. Instead of using a gap mirror that requires precise narrow gap control, the invention uses direct monolithic integration where the gain section and SOA section are fabricated adjacent to each other on the same chip with optical coupling achieved through their end facets. This extraction of the problematic gap mirror element eliminates the manufacturing precision requirement while maintaining high optical power output.
3Power
If separate amplifier components are used, then the optical power is improved, but the optical coupling losses increase due to indirect coupling requirements
Solution Approach 1:
The patent merges the gain section and SOA section into a single integrated chip structure where light generated in the gain section is directly coupled into the SOA section through their adjacent end facets on the same chip. This direct monolithic integration eliminates the need for indirect coupling paths through air gaps or external optical components, thereby minimizing optical coupling losses while achieving high optical power output.
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 achieves high output power with reduced manufacturing costs and eliminates optical coupling losses, enabling a more cost-effective and efficient production of hybrid integrated tunable lasers with small line widths.
Implementation Method 1
An active DFB grating is provided in the active layer stack, wherein the DFB grating is configured to generate the laser light without an external cavity
Implementation Method 2
a gain section configured to achieve a light gain within a laser cavity
Implementation Method 3
an SOA section configured to amplify light coupled out of the laser cavity
Data Source
Figure 1
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AI summary
A combined Gain-SOA chip is provided for forming an external cavity laser that is provided with a monolithically integrated power amplifier The Gain-SOA chip comprises a gain section (3), an SOA section (5), and an optical grating (7) arranged between the gain section and the SOA section. A laser cavity may be formed by the optical grating in combination with an external mirror (2) placed adjacent to the gain section. The grating may be formed as DFB or as DBR grating, wherein the grating may be at least partly uncovered an open to the surrounding.