Tunable Waveguide Beam Emitters Using Stress-Optic Angle Modulation
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Solution Overview
Problem
Existing photonic integrated circuits face challenges in achieving low optical loss, wavelength independence, and efficient tuning and modulation compatible with CMOS foundry processes, particularly in applications requiring precise control of optical signals and components like atomic clocks and quantum sensors.
Innovation Solution
A photonic integrated circuit (PIC) with stress optic modulators, such as PZT, is used to modulate the angle of light output from output coupler gratings, enabling efficient tuning and modulation without affecting optical losses, and is compatible with CMOS foundry processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If thermal tuning techniques are used, then wavelength independence and compatibility with planar fabrication processes are achieved, but optical losses increase and power consumption becomes high
Solution Approach 1:
The patent replaces thermal tuning mechanisms with stress-optic modulation using piezoelectric actuators. The piezoelectric actuators apply mechanical stress to the waveguide, changing the optical path length and phase through the photoelastic effect, thereby achieving tuning without thermal effects that cause optical losses
Solution Approach 2:
The patent changes the physical parameter used for tuning from temperature (thermal) to mechanical stress (piezoelectric). By applying voltage to piezoelectric actuators, the waveguide experiences stress-induced refractive index changes, enabling wavelength-independent tuning with minimal optical loss
2Ease of operation
If electrooptic techniques are used, then tuning and modulation are achieved, but optical losses increase and operating bandwidth becomes limited
Solution Approach 1:
The patent substitutes electrooptic modulators with stress-optic modulation using piezoelectric actuators. The piezoelectric effect converts electrical signals directly to mechanical stress on the waveguide, avoiding the optical absorption and heating issues inherent in electrooptic techniques
3Loss of energy
If stressoptic actuation is used, then low loss and compatibility with planar fabrication are maintained, but modulation bandwidth is limited
Solution Approach 1:
The patent implements dynamic stress-optic modulation by using piezoelectric actuators that can respond rapidly to electrical signals. The piezoelectric material's fast response time enables high-speed modulation while maintaining the low-loss advantages of stress-optic actuation, overcoming the bandwidth limitation
Solution Approach 2:
The patent uses composite structures combining piezoelectric materials with the photonic integrated circuit waveguide. This integration allows the piezoelectric actuators to efficiently transfer mechanical stress to the waveguide, enhancing the modulation bandwidth while preserving low optical losses
4Measurement precision
If table-top sized precision lasers and optics are used, then precise control for atomic applications is achieved, but system size and complexity increase
Solution Approach 1:
The patent merges multiple discrete optical components (lasers, modulators, waveguides, gratings) into a single integrated photonic circuit. The piezoelectric actuators are directly integrated with the waveguide structures, eliminating the need for external table-top equipment and achieving precise control in a compact form factor
Solution Approach 2:
The photonic integrated circuit performs multiple functions (laser tuning, modulation, beam steering) using integrated piezoelectric actuators that can control different optical parameters. This multi-functionality replaces numerous separate precision instruments with a single compact device
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 PIC achieves low optical loss, efficient tuning, and modulation bandwidth, reducing system size, weight, and cost, while providing reliable operation for applications like atomic clocks and quantum sensors.
Implementation Method 1
stressoptic, electrooptic, and thermal. These mechanisms change the physical characteristics of the waveguides, for example the optical index of refraction
Implementation Method 2
A photonic integrated circuit (PIC) with stress optic modulators, such as PZT
Data Source
AI summary
A photonic integrated circuit may include a laser with a first optical frequency related to an atomic transition, the at least one laser pre-stabilized to a frequency reference, where the at least one laser is locked to the frequency reference; a first output coupling grating which outputs light from the laser to a target; a first stress optic modulator adjacent to the first output coupler grating. The first stress optic modulator is configured to modulate the angle of light outputted from the first output coupling grating when a voltage is applied to the first stress optic modulator.