Tunable Laser Etalon Layout for Stable Wavelength Control
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Solution Overview
Problem
The etalon's periodic transmission characteristic makes wavelength control difficult due to non-monotonic increases and decreases around peak and bottom values, leading to instability in wavelength control.
Innovation Solution
An optical semiconductor device with a wavelength tunable laser element, a beam splitter that splits the outgoing beam into parallel first and second light beams, and an etalon with different optical path lengths for each beam, allowing adjustment of transmission characteristics to achieve stable wavelength control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single etalon is used for wavelength control, then the device structure is simple, but the transmission characteristic is non-monotonic around peak and bottom values making wavelength control unstable
Solution Approach 1:
The single etalon is divided into two separate etalons with different optical path lengths. Each etalon produces a transmission characteristic curve that is shifted relative to the other, allowing the system to operate in monotonic regions and achieve stable wavelength control while maintaining relatively simple device structure.
2Measurement precision
If the etalon optical path length is increased to improve wavelength resolution, then the transmission peak becomes sharper, but the control difficulty increases due to non-monotonic characteristics
Solution Approach 1:
By segmenting the wavelength control function across two etalons with different optical path lengths, each etalon can be optimized for specific wavelength ranges where their transmission characteristics are monotonic, thereby improving wavelength resolution while reducing control difficulty through selective operation in favorable regions.
Solution Approach 2:
The system changes the optical path length parameter between the two etalons to create different transmission characteristic curves. This parameter variation allows the selection of operating points where the combined transmission characteristic is monotonic, improving both wavelength resolution and control ease.
3Manufacturing precision
If production tolerance and assembly variations are reduced to improve wavelength control precision, then the manufacturing cost increases
Solution Approach 1:
The wavelength control function is segmented into two etalons with different optical path lengths, which reduces the sensitivity to individual component tolerances. This segmentation allows for more relaxed manufacturing tolerances and assembly variations while maintaining wavelength control precision, thereby reducing manufacturing cost.
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 precise and stable wavelength control by adjusting the optical path lengths and incidence angles of the light beams, reducing production tolerance and assembly variations, and allowing monotonic increases or decreases in transmission characteristics for effective wavelength selection.
Implementation Method 1
an etalon that transmits the first light beam and the second light beam, wherein an optical path length to the first light beam of the etalon is different from an optical path length to the second light beam of the etalon
Implementation Method 2
a beam splitter that splits an outgoing beam of the wavelength tunable laser element into a first light beam and a second light beam parallel to each other
Data Source
AI summary
Provided is an optical semiconductor device including: a wavelength tunable laser element; a beam splitter that splits an outgoing beam of the wavelength tunable laser element into a first light beam and a second light beam parallel to each other, and outputs the first light beam and the second light beam; and an etalon that transmits the first light beam and the second light beam, wherein an optical path length to the first light beam of the etalon is different from an optical path length to the second light beam of the etalon.