Tunable Laser With Sampled Gratings For Wavelength Tuning
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Solution Overview
Problem
Current tunable lasers for WDM-PON applications are costly and inefficient in covering a wide range of channels, requiring significant temperature changes to tune wavelengths, which is impractical for lower-cost, lower-performance applications.
Innovation Solution
A tunable laser with multiple in-line sections and sampled gratings, where each section has the same grating period but different sampling periods, allowing for independent wavelength tuning within different ranges, enabling efficient selection of channel wavelengths with reduced temperature variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single tunable laser is used to cover a wide range of channel wavelengths, then the wavelength tuning range is improved, but the temperature variation required increases significantly
Solution Approach 1:
The laser device is divided into multiple independent laser sections, each capable of generating light within a specific wavelength range. This segmentation allows each section to operate within a limited temperature range while the collective sections cover a broad wavelength spectrum, resolving the contradiction between wide tuning range and excessive temperature variation.
Solution Approach 2:
The patent implements dynamic selection among multiple laser sections based on the desired wavelength. By activating only the relevant section for the current wavelength range, the system dynamically adapts to maintain optimal operating conditions without requiring large temperature swings, thus resolving the contradiction.
2Ease of operation
If temperature control is used to tune wavelength in DFB lasers, then the wavelength can be adjusted, but the temperature range required becomes impractically large
Solution Approach 1:
Instead of using a single DFB laser requiring large temperature changes for wavelength tuning, the patent segments the laser into multiple sections with different grating periods. Each section can be tuned over a small temperature range to cover its specific wavelength band, making the overall system practical for operation while maintaining full wavelength adjustment capability.
3Adaptability or versatility
If multiple laser sections with different grating periods are used, then the wavelength coverage is improved, but the device complexity increases
Solution Approach 1:
The patent merges multiple laser sections with different grating periods into a single integrated laser device. This combining approach allows the device to achieve broad wavelength coverage through multiple sections while maintaining a unified structure that reduces overall complexity compared to using separate laser devices for each wavelength range.
Solution Approach 2:
The multi-section laser device achieves universality by being capable of generating wavelengths across a broad spectrum through a single device. This multi-functional capability eliminates the need for multiple separate lasers or wavelength conversion devices, thereby reducing system complexity while improving wavelength coverage.
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 solution allows for cost-effective, efficient tuning of multiple channel wavelengths within a smaller temperature range, facilitating the use of a single device across various subscriber locations in WDM-PON systems, enhancing deployment and maintenance efficiency.
Implementation Method 1
The sampled grating sections have the same grating period and respectively have different sampling periods to produce different wavelengths
Implementation Method 2
Each of the in-line laser sections includes a semiconductor active region for amplifying light at a wavelength in the respective wavelength range
Data Source
AI summary
A tunable laser with multiple in-line sections including sampled gratings generally includes a semiconductor laser body with a plurality of in-line laser sections configured to be driven independently to generate laser light at a wavelength within a different respective wavelength range. Sampled gratings in the respective in-line sections have the same grating period and a different sampling period to produce the different wavelengths. The wavelength of the light generated in the respective laser sections may be tuned, in response to a temperature change, to a channel wavelength within the respective wavelength range. By selectively generating light in one or more of the laser sections, one or more channel wavelengths may be selected for lasing and transmission. By using sampled gratings with the same grating period in the multiple in-line sections, the multiple section tunable laser may be fabricated more easily.