Compact Tunable Laser Device Using Folded Resonator
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Solution Overview
Problem
Current tunable laser devices are too large to be mounted in compact SFP transceiver modules, as they typically use butterfly packages that are expensive and cannot be miniaturized for TO type packages, limiting their use in high-capacity communication systems like NG-PON2.
Innovation Solution
A compact tunable external resonator-type laser device is developed using a TO type package, featuring a semiconductor laser diode chip, a tunable-selective filter, and an optical feedback-partial reflective mirror, where the laser diode chip and tunable-selective filter are disposed on a thermoelectric element, allowing wavelength tuning via temperature changes, and the optical feedback-partial reflective mirror is positioned over a 45°-reflective mirror to minimize package size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a butterfly package is used for the tunable laser device, then the laser can be tuned across multiple wavelengths, but the device volume becomes too large to be mounted in an SFP transceiver module
Solution Approach 1:
The patent reconfigures the optical resonator components from a planar butterfly package layout into a three-dimensional folded cavity structure. The light path is folded back on itself using mirrors, allowing the resonator to fit within the compact cylindrical TO package volume while maintaining the necessary optical path length for wavelength tuning across 1270-1610 nm range.
Solution Approach 2:
The patent nests multiple optical components (laser diode chip, collimating lens, tunable filter, mirrors) within the compact TO package structure. The folded resonator cavity nests the optical path within itself, and all components are integrated into the small package volume that can be mounted in SFP transceivers.
2Adaptability or versatility
If a butterfly package is used for the tunable laser device, then the laser can be tuned across multiple wavelengths, but the manufacturing cost increases
Solution Approach 1:
The patent replaces the expensive butterfly package with a TO type package that uses simpler, more cost-effective components. The folded resonator design uses standard mirrors and off-the-shelf optical components rather than specialized butterfly package components, significantly reducing manufacturing cost while maintaining wavelength tuning functionality.
3Volume of moving object
If a TO type package is used, then the device volume is reduced for SFP mounting, but tunable laser devices in TO type packages have not been previously proposed
Solution Approach 1:
The patent incorporates a tunable filter within the folded resonator cavity that can dynamically adjust the transmission wavelength. This allows the compact TO package to tune across the broad 1270-1610 nm wavelength range, providing the adaptability normally associated with larger packages. The thermoelectric element enables dynamic wavelength adjustment by changing the filter's transmission characteristics.
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
This configuration enables a compact, cost-effective tunable laser device that can be mounted in SFP transceivers, offering a smaller form factor than butterfly packages and maintaining wavelength stability within the required specifications for DWDM systems.
Implementation Method 1
the laser diode chip or the tunable-selective filter is disposed on a thermoelectric element and has an oscillation wavelength changing in accordance with a change in temperature of the thermoelectric element
Implementation Method 2
an optical feedback-partial reflective mirror that feeds some of light emitted from the laser diode chip back to the laser diode chip by reflecting it
Implementation Method 3
a collimating lens that is disposed in a light path between the laser diode chip and the optical feedback-partial reflective mirror and collimates light emitted from the laser diode chip
Implementation Method 4
a tunable-selective filter of which the transmissive wavelength changes in accordance with temperature
Implementation Method 5
a 45°-reflective mirror that changes laser light traveling horizontally to a package bottom into laser light traveling perpendicular to the package bottom
Data Source
AI summary
A semiconductor laser device which comprises a laser diode chip (100) that emits laser light; a 45° reflective mirror (400) that changes laser light traveling horizontally to a package bottom into laser light traveling perpendicular to the package bottom. The 45° reflective mirror (400) is a partial reflective mirror which has a partial reflection/partial transmission characteristic. An optical feedback-partial reflective mirror (500) is disposed along a path of light passing vertically through the 45° reflective mirror (400). The optical feedback-partial reflective mirror (500) supplies some of the laser light traveling through the 45° reflective mirror (400) back to the 45° reflective mirror 400 by reflecting a first portion of the laser light while transmitting a remaining portion of the laser light.