Fan-Out Grating Non-Linear Optical Device Broadened Gain Bandwidth
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Solution Overview
Problem
Non-linear optical devices face limitations in achieving broad gain bandwidth and wavelength tunability, particularly due to discrete poling periods in crystals, which restrict continuous fine-tuning of phase-matching conditions and effective wavelength conversion across a broad range.
Innovation Solution
A non-linear optical device with a fan-out grating structure oriented at an offset angle, utilizing a periodically ferroelectrically poled crystal with a quasi-chirped fan-out pattern, allowing for continuous phase-matching and efficient wavelength conversion across a broader bandwidth by varying the grating periods along the light beam path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If discrete poling periods are used in the crystal, then the device structure is simpler and easier to manufacture, but continuous fine-tuning of phase-matching conditions is not possible, limiting wavelength tunability
Solution Approach 1:
The patent applies local quality by creating a fan-out grating structure where different regions of the crystal have different local grating periods. The grating period varies continuously across the crystal aperture, with each local region optimized for a specific wavelength range. This allows the single crystal to handle multiple wavelengths simultaneously through spatial differentiation, resolving the contradiction between simplicity and tunability.
Solution Approach 2:
The invention transitions from one-dimensional uniform grating periods to two-dimensional fan-out grating patterns with varying periods across the crystal aperture. By introducing spatial variation in the grating period dimension, the device achieves continuous wavelength tuning capability while maintaining a single crystal structure, effectively adding a dimensional aspect to the grating design.
2Adaptability or versatility
If the crystal period is translated to tune wavelength, then wavelength tuning is achieved, but the gain bandwidth remains limited due to discrete period values
Solution Approach 1:
The patent implements dynamics by making the grating period variable rather than fixed. The fan-out grating structure provides a continuous distribution of grating periods across the crystal aperture, allowing the effective period to be dynamically selected by adjusting the input beam position. This dynamic period selection enables continuous wavelength tuning and broadened gain bandwidth without requiring discrete crystal translations.
Solution Approach 2:
The invention applies parameter changes by varying the grating period parameter continuously across the crystal aperture rather than using discrete values. This continuous parameter variation allows the device to accommodate a broader range of wavelengths and achieve enhanced gain bandwidth while maintaining operational flexibility through beam position adjustment.
3Adaptability or versatility
If fan-out grating structure is used, then wavelength conversion across broader range is achieved, but the gain bandwidth is still limited without offset angle optimization
Solution Approach 1:
The patent applies asymmetry by introducing an offset angle between the fan-out grating orientation and the crystal optical axis. This asymmetric configuration optimizes the phase-matching conditions for a broader range of wavelengths, enhancing the gain bandwidth. The offset angle creates an asymmetric distribution of effective grating periods that better matches the spectral requirements for broadened wavelength conversion.
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 solution enables broadened gain bandwidth and enhanced wavelength tunability, allowing efficient nonlinear processes over a wider range of wavelengths, while maintaining operational flexibility through crystal translation and rotation.
Implementation Method 1
Non-linear optical devices may be used to convert an input light beam having a first wavelength into an output light beam having a second wavelength, where the second wavelength may be harmonically related to the first wavelength
Implementation Method 2
The fan-out grating structure 20 produces a continuously varying phase-matching condition across the aperture width of the device 100
Implementation Method 3
In normal dispersive materials, for example lithium Niobate, bands having shorter lengths interact more efficiently with shorter wavelengths of the input beam 12, and bands having longer lengths interact more efficiently with longer wavelengths of the input beam 12
Data Source
AI summary
An optical crystal for converting an input light beam, the crystal having an ingress surface, an egress surface, and a fan-out grating has a fan-out pattern oriented at an offset angle θ in the range of 1° to 45° with respect to a beam entry plane at a beam ingress location.