Micro-ring resonator thermal tuning via backside etching and intermediary sensor
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Solution Overview
Problem
Existing micro-ring resonators (MRRs) in open-cavity photonic integrated circuits (OCPICs) face challenges with thermal isolation and temperature control due to poor thermal conductivity of the oxide cladding, leading to inaccurate temperature measurement and thermal cross-talk from adjacent electronic components, which affects the stability and efficiency of wavelength division multiplexing systems.
Innovation Solution
A backside etching process is employed to form cavities through the silicon substrate and cladding, enhancing thermal isolation, and a metallic temperature sensor with a low refraction index interface layer is used to accurately measure the MRR temperature, while reorganizing the bump and MRR layout to increase cavity diameter and reduce thermal cross-talk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If channels are formed around the MRR to improve thermal isolation, then thermal cross-talk is limited, but temperature measurement accuracy deteriorates due to poor thermal conductivity of the oxide cladding
Solution Approach 1:
A metallic temperature sensor is introduced as an intermediary component between the MRR and the measurement system. The sensor is positioned in direct thermal contact with the MRR through a low-refraction-index interface layer, allowing accurate temperature measurement without relying on the thermally-insulating oxide cladding. This intermediary approach enables precise temperature sensing while maintaining the thermal isolation benefits of the cladding structure.
Solution Approach 2:
The temperature sensor is positioned in a different spatial dimension - directly above the MRR in the vertical dimension rather than being laterally separated by the oxide cladding. This dimensional change allows the sensor to bypass the thermal isolation barrier and achieve accurate temperature measurement through direct vertical thermal coupling.
2Ease of manufacture
If an integrated heater is formed in the center of the MRR using P and P+ doping regions, then fabrication costs are minimized, but thermal isolation deteriorates leading to thermal cross-talk from adjacent electronic components
Solution Approach 1:
A thin oxide cladding layer is formed over the MRR structure, creating a thermal isolation shell that separates the integrated heater from adjacent electronic components. This thin film approach maintains the low-cost integrated heater fabrication while introducing effective thermal barrier properties to prevent heat propagation to surrounding components.
Solution Approach 2:
The device structure is segmented into distinct thermal zones using the oxide cladding as a separation layer. The integrated heater region is thermally isolated from adjacent electronic components by this cladding segment, allowing independent thermal management of each functional block while maintaining the cost-effective doped-region heater design.
3Ease of manufacture
If the oxide cladding is used to cover the MRR, then fabrication is simplified, but thermal conductivity deteriorates causing inaccurate temperature measurement
Solution Approach 1:
A metallic temperature sensor serves as an intermediary that bypasses the thermal isolation provided by the oxide cladding. The sensor is positioned in direct thermal contact with the MRR, allowing it to accurately measure the MRR temperature without being affected by the poor thermal conductivity of the oxide cladding layer.
Solution Approach 2:
Instead of measuring temperature through the oxide cladding (which provides poor thermal coupling), the system uses a dedicated temperature sensor that creates a direct thermal copy or replica of the MRR temperature condition, enabling accurate measurement independent of the cladding's thermal properties.
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
The solution provides improved thermal isolation and accurate temperature control of MRRs, enhancing the stability and efficiency of wavelength division multiplexing systems by minimizing thermal cross-talk and optimizing thermal tuning efficiency.
Implementation Method 1
A heater is normally integrated into the MRR to enable wavelength resonance tuning. Applying heat shifts the resonance frequency of the MRR.
Implementation Method 2
A backside etching process is employed to form cavities through the silicon substrate and cladding, enhancing thermal isolation
Implementation Method 3
a metallic temperature sensor with a low refraction index interface layer is used to accurately measure the MRR temperature
Data Source
AI summary
Embodiments disclosed herein include optoelectronic systems and methods of forming such systems. In an embodiment, an optoelectronic system comprises a first substrate, a second substrate over the first substrate, and a micro-ring resonator (MRR) over the second substrate. In an embodiment, a heater is integrated into the MRR, a cladding is over the MRR, and an opening is through the first substrate and the second substrate to expose a bottom surface of the MRR.