Optical Crystal Waveguide Structuring With Smooth Steep Sidewalls
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Solution Overview
Problem
Conventional methods for manufacturing optically usable waveguide structures in optical crystals are limited in flexibility and design range, requiring complex and expensive process chains, and result in waveguide structures with insufficient quality, particularly affecting their performance in visible and near-infrared wavelength ranges.
Innovation Solution
A method using ultrashort pulse laser radiation with wavelengths in the green or UV range and angled laser beam incidence to produce waveguide structures with steep sidewalls, allowing for the fabrication of high-quality waveguides capable of guiding light in visible and near-infrared wavelengths, and incorporating features like frequency-converted light generation and nonlinear optical processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If laser ablation with femtosecond laser pulses is used to create grooves for strut waveguides, then waveguide structures can be produced, but the sidewalls become rough which reduces waveguide quality and increases losses
Solution Approach 1:
The patent changes the laser pulse duration parameter from femtosecond range to picosecond range (1-100 ps), and adjusts the repetition rate to 100 kHz - 1 MHz. These parameter changes modify the ablation mechanism to produce smoother sidewalls while maintaining the groove formation capability, directly resolving the contradiction between ease of manufacture and manufacturing precision
Solution Approach 2:
The patent employs periodic laser pulsing with repetition rates between 100 kHz and 1 MHz. This periodic action allows controlled material removal with sufficient cooling time between pulses, preventing thermal accumulation that causes roughness while maintaining efficient ablation for waveguide production
2Ease of manufacture
If conventional laser ablation methods are used, then waveguide structures can be fabricated, but complex and expensive process chains are required which limits flexibility and increases cost
Solution Approach 1:
The patent makes the laser system universal by enabling it to perform multiple functions: groove formation, sidewall smoothing, and waveguide structure creation all with the same picosecond laser source. This eliminates the need for multiple specialized process steps and equipment, reducing process chain complexity while maintaining fabrication capability
Solution Approach 2:
The patent merges the groove formation and sidewall smoothing operations into a single integrated process using the picosecond laser. By combining these previously separate steps into one unified approach, the process chain becomes simpler and more flexible while reducing overall complexity
3Ease of manufacture
If laser ablation creates grooves with V-shaped flanks, then ridge waveguides can be formed, but light loss increases due to non-rectangular cross-section
Solution Approach 1:
The patent changes the laser parameters to picosecond pulse duration and optimized repetition rate, which fundamentally alters the ablation morphology from V-shaped flanks to near-rectangular cross-section. This parameter change enables the formation of grooves with vertical sidewalls that minimize light loss while maintaining ease of fabrication
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 method enhances the quality of waveguide structures by reducing sidewall roughness, enabling efficient light guidance in both visible and near-infrared ranges, and allows for the creation of complex geometries with reduced light loss and improved efficiency for quantum optical setups.
Implementation Method 1
shining a pulsed laser beam onto a surface of the optical crystal, and moving the pulsed laser beam and the optical crystal relative to each other along a feed direction to remove material from the optical crystal along at least one ablation path
Data Source
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AI summary
The invention relates to a method for producing at least one optically usable microstructure, in particular at least one waveguide structure (8a-c), on an optical crystal (2), comprising the steps of: radiating a pulsed laser beam (4) onto a surface (2a) of the optical crystal (2); and moving the pulsed laser beam (4) and the optical crystal (2) relative to one another along an advance direction (12) to remove material of the optical crystal (2) along at least one ablation path (13) to form the optically usable microstructure, in particular the waveguide structure (8a-c). The pulsed laser beam (4) is radiated onto the surface (2a) of the optical crystal (2) with pulse durations (τ) of less than 5 ps, preferably of less than 850 fs, particularly preferably of less than 500 fs, in particular of less than 300 fs, and with a wavelength (λL) of less than 570 nm, preferably of less than 380 nm.