Compact TO Housing for DFB Lasers with Impedance Matching
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Solution Overview
Problem
Existing transistor outline (TO) housings for semiconductor lasers are either too large, expensive, or complex to manufacture, and are not suitable for Distributed Feedback (DFB) lasers due to impedance mismatch and manufacturing limitations.
Innovation Solution
A compact TO housing design featuring a base part with a mounting area for a thermoelectric cooler and conductor traces secured by glass seals, which allows for high-frequency signal transmission and easy manufacturing through stamping, with a sub-mount providing optimized impedance characteristics for DFB lasers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional TO housing design with lateral signal inputs is used, then the housing can accommodate EMLs, but it is too large and expensive to manufacture for DFB laser applications
Solution Approach 1:
The housing is divided into a base part and a cap that can be separately manufactured and then assembled. The base part contains the mounting area for the TEC and conductor traces, while the cap provides the protective enclosure with an optical window. This segmentation allows each part to be optimized for its specific function and manufactured using appropriate processes.
Solution Approach 2:
Instead of providing lateral signal inputs as in conventional EML housings, the invention inverts the connection approach by providing signal feedthroughs in the base part with conductor traces that extend upward to the mounting area. This inverted configuration enables compact design while maintaining electrical connectivity for high-frequency DFB laser signals.
2Ease of manufacture
If a TO housing with connection pins projecting downwards is used, then signal transmission is enabled, but the housing cannot be produced by stamping or deep drawing due to complicated manufacture
Solution Approach 1:
The housing structure is segmented into a simple base part that can be stamped or deep-drawn, and a separate cap. The base part features a flat upper surface with integrated mounting areas and conductor traces, eliminating the need for complex internal geometries that would prevent stamping or deep drawing processes.
Solution Approach 2:
The conductor traces are arranged in a planar configuration on the upper surface of the base part, extending horizontally rather than vertically downward as in conventional designs. This dimensional reorganization allows the housing to be manufactured by stamping or deep drawing while still providing effective electrical connections for high-frequency signals.
3Reliability
If conventional housing designs are used, then manufacturing is simpler, but they are not suitable for DFB lasers due to impedance mismatch and lack of high-frequency signal transmission capability
Solution Approach 1:
The base part features localized mounting areas with optimized conductor trace geometries specifically designed for high-frequency signal transmission. The conductor traces are positioned and dimensioned to achieve proper impedance matching (typically 50 ohms) for DFB laser operation, while other areas of the base part maintain simple structures for easy manufacturing.
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 enables high data rates of 5 Gbit/s or more while being cost-effective and easy to produce, with impedance matching in the GHz range, suitable for DFB lasers and thermoelectric coolers.
Implementation Method 1
the feedthroughs comprise connection pins which are secured, by glass seals, in through-holes in the base part
Implementation Method 2
thermoelectric coolers (TECs) are used, which are installed together with the laser in a so-called transistor outline housing (TO housing)
Data Source
AI summary
A transistor outline (TO) housing comprising a base part having a mounting area for a thermoelectric cooler, wherein the base part has at least two feedthroughs for connecting an optoelectronic component. A support extends from the upper surface of the base part, which support has at least two conductor traces arranged thereon, each of which is connected to a respective one of the feedthroughs for connecting the optoelectronic component.