Silicon Nitride Wavelength Selector for Stable Laser Frequency Locking
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Solution Overview
Problem
Existing optical wavelength lockers face challenges in achieving precise control of resonance frequency due to high temperature coefficient of silicon-based components, which limits the stability and tunability of laser frequencies.
Innovation Solution
An integrated wavelength selector is designed with a ring waveguide made of a material with a lower temperature coefficient of resonant frequency than silicon, such as silicon nitride, coupled with a micro-heater and micro-temperature sensor, allowing for precise temperature control and frequency locking of optical signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon-based components are used in wavelength lockers, then the device can be manufactured with standard semiconductor processes, but the temperature coefficient of resonant frequency is high which limits frequency stability
Solution Approach 1:
The patent employs a composite structure where a silicon nitride ring resonator is integrated with a silicon substrate containing the heater and temperature sensor. The silicon nitride waveguide provides low TCF for frequency stability while the silicon substrate enables standard semiconductor manufacturing processes. This composite approach resolves the contradiction between ease of manufacture and frequency stability.
Solution Approach 2:
The patent changes the material parameter (TCF) of the waveguide from silicon to silicon nitride. Silicon nitride has a significantly lower temperature coefficient of resonant frequency compared to silicon, which directly addresses the frequency stability issue while maintaining compatibility with standard fabrication processes through modified semiconductor manufacturing.
2Device complexity
If standard silicon-based ring resonators are used, then the device structure is simple, but precise temperature control is difficult due to high temperature coefficient
Solution Approach 1:
The patent uses a composite material system where silicon nitride waveguides are fabricated on a silicon substrate. The silicon nitride provides thermal stability and low TCF, reducing the impact of temperature variations on resonant frequency. This material choice improves temperature control precision while maintaining a relatively simple integrated device structure that can be manufactured using standard semiconductor processes.
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 enhanced temperature stability and tunability of laser frequencies, enabling precise control within ±1 GHz and reducing the need for stringent temperature control, thus improving the performance of wavelength lockers and tunable lasers.
Implementation Method 1
an integrated heater on the substrate
Implementation Method 2
an integrated silicon temperature sensor on the substrate
Implementation Method 3
a ring waveguide of a first material disposed vertically between the integrated heater and the integrated silicon temperature sensor
Implementation Method 4
The resonance frequency of the ring resonator serves as a reference frequency. The frequency of a signal of interest can be compared to the reference frequency provided by the ring resonator.
Data Source
AI summary
Integrated wavelength selectors are described. The wavelength selector may include silicon nitride ring resonator disposed vertically between a heater and a temperature sensor. The temperature sensor may be formed of silicon in some embodiments. The wavelength selector may be coupled to the output port of a tunable laser, or may be disposed within a laser cavity.