Wavelength Tunable Laser Stray Light Correction
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Solution Overview
Problem
Conventional wavelength tunable laser systems face inaccuracies in emission wavelength tuning due to stray components affecting the ratio of light detected by photodiodes, leading to erroneous wavelength determination and reduced precision in optical communication systems.
Innovation Solution
A laser apparatus with a wavelength tunable laser diode integrated with a semiconductor optical amplifier and a wavelength monitor that includes optical filters and photodiodes to sense raw and filtered beams, with a controller calculating the ratio of filtered to raw beams after subtracting stray components, ensuring accurate emission wavelength tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional wavelength detection method using photodiodes and optical filters is used, then wavelength tuning function is achieved, but measurement precision deteriorates due to stray components affecting the detected light ratio
Solution Approach 1:
The patent extracts and separately measures the stray light component by blocking the main laser beam while allowing stray light to reach the photodiodes. This separated measurement enables independent quantification of stray light interference, which is then subtracted from the total detected signal to obtain the accurate wavelength-dependent light ratio.
Solution Approach 2:
The patent implements a feedback mechanism where the measured stray light component is fed back into the calculation process. The controller continuously monitors the stray light level and dynamically adjusts the wavelength determination by subtracting the stray light contribution from the total detected signal, ensuring accurate wavelength control despite stray light presence.
2Measurement precision
If high precision wavelength tuning is implemented to meet communication system requirements, then signal wavelength exactness is improved, but device complexity increases due to additional correction mechanisms
Solution Approach 1:
The wavelength monitoring system performs self-calibration by automatically measuring and characterizing its own stray light components during operation. The system uses built-in beam blocking mechanisms and internal photodiodes to autonomously quantify and compensate for stray light interference without requiring external calibration equipment or manual intervention, thereby achieving high precision while limiting complexity growth.
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
Enhances the accuracy of emission wavelength tuning by accounting for stray components, thereby improving the precision of the emission wavelength to meet the exacting requirements of modern optical communication systems.
Implementation Method 1
an optical filter, a first photodiode (PD) that senses a raw beam, which is not transmitted through the optical filter, and a second PD that senses a filtered beam, which is split from the raw beam and transmitted through the optical filter
Implementation Method 2
a first photodiode (PD) that senses a raw beam, which is not transmitted through the optical filter, and a second PD that senses a filtered beam
Data Source
AI summary
A method to tune an emission wavelength of a wavelength tunable laser apparatus is disclosed. The laser apparatus implements, in addition to a wavelength tunable laser diode (t-LD) integrating with a semiconductor optical amplifier (SOA), a wavelength monitor including an etalon filter. The current emission wavelength is determined by a ratio of the magnitude of a filtered beam passing the etalon filter to a raw beam not passing the etalon filter. The method first sets the SOA in an absorbing mode to sense stray component disturbing the wavelength monitor, then correct the ratio of the beams by subtracting the contribution from the stray component.