Silicon Photonic Frequency Shifter Using Saw-Tooth Phase Modulation
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Solution Overview
Problem
Existing optical frequency shifting devices, such as Acousto-Optic Modulators (AOMs), are bulky and expensive, making them unsuitable for compact and cost-effective integration in silicon photonics systems.
Innovation Solution
The integration of a ridge waveguide with a PIN diode in silicon photonics systems to apply a saw-tooth phase shift to propagating light, utilizing a phase modulator and electronic drive circuit for linear phase change proportional to time, enabling compact and cost-effective frequency shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Acousto-Optic Modulators (AOM) are used for optical frequency shifting, then frequency shifting function is achieved, but device size becomes bulky and cost increases
Solution Approach 1:
The patent replaces the mechanical Acousto-Optic Modulator with an all-optical frequency shifting mechanism using a Mach-Zehnder interferometer configuration. The mechanical AOM is substituted by optical path manipulation through phase modulators and interferometric mixing, eliminating the need for bulky mechanical components while achieving the same frequency shifting function.
Solution Approach 2:
The patent transitions from a single-component mechanical frequency shifter to a multi-path optical interferometric system. By distributing the frequency shifting function across multiple optical paths and using interferometric mixing in the Mach-Zehnder configuration, the system achieves compact integration while maintaining the frequency shifting capability.
2Reliability
If Acousto-Optic Modulators (AOM) are used for optical frequency shifting, then frequency shifting function is achieved, but device cost increases
Solution Approach 1:
The patent creates a multi-functional optical system where the Mach-Zehnder interferometer serves both as a signal processing element and a frequency shifting mechanism. The same optical components (phase modulators, beam splitters, combiners) perform multiple functions including signal modulation, path interference, and frequency shifting, thereby reducing the need for specialized expensive components.
Solution Approach 2:
The patent uses optical copying through interferometric mixing where the reference beam serves as a template for frequency translation. The signal beam is effectively 'copied' and mixed with the reference beam in the interferometer, transferring the frequency characteristics without requiring direct mechanical interaction, thus reducing component cost.
3Volume of moving object
If saw-tooth phase shift is applied to propagating light, then compact frequency shifting is achieved, but phase modulation complexity increases
Solution Approach 1:
The patent applies periodic saw-tooth phase modulation to the reference beam in the Mach-Zehnder interferometer. This periodic phase shifting creates the desired frequency translation through interferometric mixing, achieving compact frequency shifting while managing modulation complexity through the regular, repeating nature of the saw-tooth waveform.
Solution Approach 2:
The patent introduces the Mach-Zehnder interferometer as an intermediary system that mediates between the phase modulated reference beam and the signal beam. The interferometer configuration transforms the complex phase modulation into simple frequency shifting through optical path interference, reducing the overall system complexity.
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 approach provides a compact, inexpensive optical frequency shifter suitable for silicon photonics chips, enhancing signal processing and detection in applications like Lidar systems by enlarging the beat frequency for easier detection.
Implementation Method 1
a phase modulator configured to change the phase of light passing through it
Implementation Method 2
a pair of photodetectors configured to demodulate the combined first and second light beams to receive the signal information from the application device
Data Source
AI summary
An optical device having a frequency shifter, the frequency shifter having an optical component having a phase modulator having a silicon material substrate, a buried oxide layer disposed on the silicon material substrate, a silicon waveguide disposed on the buried oxide layer, wherein the silicon waveguide is configured to guide a light, and a pair of electrodes disposed on the silicon waveguide, wherein the phase modulator is configured to change the phase of the light passing through it, and an electronic drive circuit in electrical communication with the phase modulator such that the phase change is linearly proportional to time. The disclosed optical device is configured to provide optical frequency shifting capabilities to and be integrated within silicon photonics-based devices, wherein the disclosed optical device is configured to facilitate this frequency shifting capability while being compact and having a low cost.