Twin Waveguide Array Spectrometer for SWIFTS Resolution
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Solution Overview
Problem
Stationary-Wave Integrated Fourier-Transform Spectrometry (SWIFTS) technology faces limitations due to under-sampling of interferograms, which restricts spectral resolution and bandwidth, and the scattering efficiency of nano-samplers degrades over bandwidth, making precise measurement of standing wave intensity complicated.
Innovation Solution
A Fourier transform spectrometer implemented on a photonic integrated circuit (PIC) using twin array waveguides with a preset intersecting angle to determine spectral and spatial resolutions, allowing for high spatial resolution sampling and improved spectral information measurement across all wavelengths simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If nano-samplers are used to sample the evanescent field in SWIFTS, then spectral measurement is achieved, but scattering efficiency degrades over bandwidth and measurement precision becomes complicated
Solution Approach 1:
The patent replaces the mechanical/optical sampling approach using nano-samplers with an integrated photonic circuit approach using waveguide arrays. The standing wave pattern is sampled through the evanescent field coupling to adjacent waveguides, eliminating the need for nano-samplers and their associated scattering efficiency degradation issues across bandwidth.
Solution Approach 2:
The patent introduces an intermediary waveguide structure between the input waveguide and detector. The evanescent field from the input waveguide couples to adjacent waveguides in the array, which act as intermediaries to sample the standing wave pattern without requiring direct nano-sampler interaction, thereby maintaining scattering efficiency across the bandwidth.
2Device complexity
If under-sampling is used in SWIFTS, then device complexity is reduced, but spectral resolution and bandwidth are limited
Solution Approach 1:
The patent divides the sampling function across multiple waveguides in an array structure. Each waveguide in the array samples a specific portion of the standing wave pattern through evanescent field coupling, with the number of waveguides determining the sampling density. This segmentation allows high spectral resolution without requiring complex individual sampling elements.
Solution Approach 2:
The patent transitions from one-dimensional linear sampling to a multi-dimensional waveguide array structure. The standing wave pattern is sampled across multiple spatial dimensions by utilizing the evanescent field coupling to adjacent waveguides, enabling high spectral resolution and bandwidth through the additional spatial dimension provided by the array configuration.
3Ease of manufacture
If a single-mode waveguide with fixed mirror is used, then standing wave is created, but the linear configuration limits spectral bandwidth
Solution Approach 1:
The patent combines multiple waveguides into an array structure that shares a common input waveguide. The standing wave pattern generated in the input waveguide is simultaneously coupled to multiple adjacent waveguides, merging the sampling function across multiple channels to achieve extended spectral bandwidth while maintaining the simplicity of a single-mode waveguide configuration.
Solution Approach 2:
The patent creates a multi-functional waveguide array where the same evanescent field coupling mechanism serves multiple purposes: creating the standing wave pattern, sampling the interferogram, and enabling spectral analysis across a broad bandwidth. This universal approach allows a single structure to perform multiple functions that would otherwise require separate components.
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 high optical throughput, compact size, and high resolution spectroscopy with enhanced spectral information measurement capabilities, overcoming the limitations of conventional SWIFTS technology by achieving sub-wavelength sampling and improved scattering efficiency.
Implementation Method 1
The optical signal from the first waveguide array and the optical signal from the second waveguide array intersect at a preset intersecting angle at an output plane of the PIC
Implementation Method 2
coupled sensing elements to the 'evanescent' part of 'standing waves' within a single-mode waveguide
Data Source
AI summary
A Fourier transform spectrometer implemented on a photonic integrated circuit (PIC) is provided. An input optical signal waveguide carries an input optical signal to be analyzed to an on-chip Y branch splitter to split the input signal equally to carry coupled-optical signals related to the input optical signal into twin array waveguides of a first waveguide array and a second waveguide array. The optical signal from the first waveguide array and the optical signal from the second waveguide array intersect at a preset intersecting angle at an output plane of the PIC such that the spectral and spatial resolutions of the interferogram of the spectrometer are determined by the intersecting angle.