Thermally Tunable Thin-Film Filter for Wavelength Selective Photodiode
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Solution Overview
Problem
Current wavelength-agile technologies in DWDM backbone networks are unable to meet the cost constraints of the end-user market, and existing FTTX systems rely on static filters to select channels, limiting the dynamic provisioning of wavelengths needed for advanced services like HDTV and telepresence.
Innovation Solution
The development of an integrated wavelength selectable photodiode using a thermally tunable thin-film filter, which allows for dynamic wavelength selection and detection of optical signals, enabling flexible high-bandwidth network architectures with minimal cost and reduced thermal noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If static filters are used to select channels in FTTX systems, then device complexity is reduced and manufacturing cost is lowered, but adaptability and dynamic wavelength provisioning capability are limited
Solution Approach 1:
The patent applies the dynamics principle by transforming static optical filters into dynamically tunable filters using thermally actuated micro-electro-mechanical systems (MEMS). The filter structure includes a movable mirror or membrane that can be positioned at different locations by applying thermal energy, thereby changing the optical path length and selecting different wavelengths. This allows the system to adapt to different wavelength requirements while maintaining a relatively simple integrated structure suitable for FTTX applications.
Solution Approach 2:
The patent utilizes parameter changes by modifying the physical parameters of the filter system through thermal actuation. By changing the temperature of the MEMS actuator, the mechanical position of the filter element is altered, which in turn changes the optical resonance condition or filter center wavelength. This enables dynamic wavelength selection without requiring complex mechanical assemblies, resolving the contradiction between adaptability and device complexity.
2Adaptability or versatility
If wavelength-agile technologies from DWDM backbone networks are deployed in FTTX, then adaptability and service capability are improved, but manufacturing cost and complexity increase beyond end-user market constraints
Solution Approach 1:
The patent extracts the essential wavelength selection function from complex DWDM backbone network technologies and implements it in a simplified form suitable for FTTX. By using integrated MEMS-based tunable filters on compact substrates, the invention removes unnecessary complexity while retaining the core adaptability function. This extraction approach enables wavelength-agile functionality at a manufacturing cost and complexity level appropriate for end-user market deployment.
Solution Approach 2:
The patent creates a simplified copy of wavelength selection functionality adapted for FTTX applications. Instead of implementing full DWDM backbone network complexity, the invention replicates the essential wavelength tuning capability using cost-effective integrated photonic structures with MEMS actuators. This copied functionality provides sufficient adaptability for advanced FTTX services while meeting manufacturing cost constraints.
3Adaptability or versatility
If thermally tunable filters are used for wavelength selection, then adaptability is improved, but thermal noise increases and signal-to-noise ratio deteriorates
Solution Approach 1:
The patent applies segmentation by separating the thermal actuation function from the optical detection function in space and time. The MEMS filter element is thermally actuated only during wavelength switching transitions, and once positioned, it maintains the selected wavelength without continuous heating. This segmented operation reduces thermal noise generation compared to continuous thermal tuning, while still providing the required wavelength adaptability for service provisioning.
Solution Approach 2:
The patent utilizes periodic action by implementing wavelength tuning only when service provisioning requires channel changes, rather than continuous tuning. The MEMS filter is actuated periodically to switch between wavelengths as needed, and remains stationary during signal transmission. This periodic actuation minimizes thermal noise generation while maintaining the ability to dynamically select wavelengths for different services.
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 provides a low-cost, reliable, and manufacturable hardware solution for FTTX networks, enabling flexible wavelength control at the end-user node, supporting advanced services by dynamically selecting wavelengths and improving signal-to-noise ratio.
Implementation Method 1
thermally tunable thin-film filter
Implementation Method 2
thin-film filter
Implementation Method 3
photodiode
Data Source
AI summary
An integrated wavelength selectable photodiode includes a device package having an input that receives an optical signal. A set-and-hold, thermally tunable thin-film filter is positioned in the device package and includes an input that is optically coupled to the input of the device package. The set-and-hold, thermally tunable thin-film filter passes light with a predetermined optical bandwidth to an output. An optical element collimates an incident optical beam onto the input of the set-and-hold, thermally tunable thin-film filter. A detector is positioned in the device package and includes an input that is optically coupled to the output of the set-and-hold, thermally tunable thin-film filter. The detector detects data received by the integrated wavelength selectable photodiode.