Acousto-Optic Tunable Filter Wavelength Correction
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Solution Overview
Problem
Existing optical spectrum analyzers face challenges in achieving high-speed measurements and accurate wavelength detection due to mechanical driving parts and limited tunable ranges, with previous technologies either being slow or having narrow measurement capabilities.
Innovation Solution
The use of a waveguide acousto-optic tunable filter (AOTF) with a piezoelectric substrate, optical waveguides, and an Interdigital Transducer (IDT) that converts light modes, combined with a light source and arithmetic device for precise wavelength correction using reference light, allowing for high-speed and accurate optical spectrum analysis without mechanical parts and with a wide tunable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an arrayed waveguide grating with thermo-regulation is used, then the optical spectrum analyzer can measure wavelengths accurately, but the measurement speed is slow due to the time required for temperature change
Solution Approach 1:
The patent replaces the thermal regulation mechanism (heater/Peltier element) with an acousto-optic tuning mechanism. The AOTF uses acoustic waves modulated by an IDT to selectively diffract specific wavelengths, eliminating the need for slow thermal changes while enabling rapid wavelength switching through electrical signal control.
2Productivity
If a piezoelectric element is used to extend or contract the fiber grating, then the optical spectrum analyzer can perform high speed measurements, but the tunable range becomes narrow
Solution Approach 1:
The patent replaces the piezoelectric mechanical deformation mechanism with an acousto-optic field interaction mechanism. The AOTF allows for a broader tunable range by adjusting the acoustic frequency and driving voltage, enabling wavelength tuning beyond the limited range achievable through piezoelectric strain on fiber gratings.
3Measurement precision
If an arrayed waveguide grating with thermo-regulation is used, then the optical spectrum analyzer can extract light at target wavelengths, but the device becomes large due to the inclusion of heating elements and temperature control mechanisms
Solution Approach 1:
The patent eliminates bulky thermal management components (heaters, heat sinks, temperature sensors, and control circuits) by using the compact AOTF device. The AOTF achieves wavelength selection through acoustic wave modulation in a small integrated structure, dramatically reducing the overall device footprint while maintaining wavelength selection capability.
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 configuration enables high-speed and accurate optical spectrum measurement with improved precision, reducing size and cost while maintaining accuracy across varying temperatures, by using a waveguide acousto-optic tunable filter that does not require mechanical driving parts and has a wide tunable range.
Implementation Method 1
an IDT arranged to convert the mode of light being propagated in the middle of the optical waveguide
Implementation Method 2
a piezoelectric substrate, an optical waveguide provided on the piezoelectric substrate
Data Source
AI summary
An optical spectrum analyzer detects a light output that is dependent on the frequency of light in a wavelength range of light to be measured. The optical spectrum analyzer includes a waveguide acousto-optic tunable filter including a piezoelectric substrate, optical waveguides, and an IDT, a light source for providing, to the waveguide acousto-optic tunable filter, reference light having a particular wavelength outside the wavelength range, a driving circuit for providing, to the waveguide acousto-optic tunable filter, a high frequency signal for exciting an IDT, and an arithmetic device that, on the basis of the wavelength of selected light when reference light is incident, and an exciting frequency, corrects the wavelength of the selected light, which is obtained from the light to be measured.