Pulse Width Conversion Device Using Segmented Diffraction Gratings
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Solution Overview
Problem
The configuration of pulse width conversion devices requires at least two diffraction gratings or one long diffraction grating, making it difficult to downsize due to geometric interference, especially when using large diffraction angles.
Innovation Solution
A pulse width conversion device with a spectroscopic element that disperses input light rays at constant incident angles to output them at wavelengths-dependent angles, utilizing a first, second, and third optical system to manage light paths and reduce the number of diffraction gratings, allowing for a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional pulse width conversion devices use at least two diffraction gratings or one long diffraction grating, then the device can achieve pulse width conversion function, but the device size becomes large due to geometric interference
Solution Approach 1:
The patent divides the function of a single long diffraction grating into multiple short diffraction gratings (first, second, and third diffraction gratings). Each grating performs a portion of the dispersion function, and together they achieve the same overall effect as one long grating, thereby reducing geometric interference and device size while maintaining the pulse width conversion capability
Solution Approach 2:
The patent changes the spatial arrangement of the optical system by introducing specific optical paths and folding the optical layout. The light rays are guided through multiple reflections and transmissions between the diffraction gratings and optical elements, effectively utilizing three-dimensional space to reduce the footprint of the device while maintaining functional performance
2Productivity
If large diffraction angles are used to achieve effective pulse width conversion, then the conversion efficiency is improved, but geometric interference increases making downsizing difficult
Solution Approach 1:
By segmenting the diffraction function across multiple gratings, each grating can operate at smaller, more manageable angles. The cumulative dispersive effect of multiple gratings with moderate angles achieves the same pulse width conversion as a single grating with a large angle, thereby reducing geometric interference while maintaining conversion efficiency
Solution Approach 2:
The patent introduces optical elements (mirrors, lenses, and optical paths) as intermediaries to guide light rays between the diffraction gratings. These intermediaries enable the system to achieve effective pulse width conversion with smaller diffraction angles by carefully controlling the optical path length and angle of incidence, thereby reducing geometric interference
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 the downsizing of pulse width conversion devices and optical amplifier systems by reducing geometric interference and the number of diffraction gratings, improving design flexibility and efficiency.
Implementation Method 1
a spectroscopic element that disperses the input light pulse, input along a first optical path, to output the light rays at output angles according to their wavelengths along a second optical path
Implementation Method 2
elements such as diffraction gratings utilizing the diffraction effect due to its device structure
Data Source
AI summary
An input light pulse Pi, input at a constant incident angle to a transmission-type diffraction grating 20, is dispersed according to the wavelengths to be output at output angles according to the wavelengths, to be reflected by reflecting mirrors 41, 42, and 43 in series, and thereafter, the light rays are input at incident angles according to their wavelengths to the transmission-type diffraction grating 20, to be output at a constant output angle from the transmission-type diffraction grating 20. The optical path for the light rays of respective wavelength components, output at the constant output angle from the transmission-type diffraction grating 20, is folded back by a rectangular prism 40, to be input at a constant incident angle to the transmission-type diffraction grating 20, and the light rays are output at output angles according to their wavelengths, to be reflected by the reflecting mirrors 43, 42, and 41 in series, and are thereafter input at incident angles according to their wavelengths to the transmission-type diffraction grating 20. The light rays, input at the incident angles according to their wavelengths to the transmission-type diffraction grating 20, are coupled by the transmission-type diffraction grating 20, to be output as an output light pulse Po. Thereby, realizing the pulse width conversion device and the optical amplifier system, which are easily downsized.