Journal/Magazine
Current Optics and Photonics
Vol. 6, No.2(Apr. 2022)
한국광학회지
Vol. 33, No.2(Apr. 2022)
K-Light
Vol5, No.2(Apr. 2022)
Editors Pick
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![[Editor's Pick] Current Optics and Photonics Vol. 6 no. 3 (2022 June)](http://www.osk.or.kr/upload/posts_thumb/2022/06/1656031644_61593000_163862715.png)
[Editor's Pick] Current Optics and Photonics Vol. 6 no. 3 (2022 June)
Spectral Reconstruction for High Spectral Resolution in a Static Modulated Fourier-transform Spectrometer
Ju Yong Cho1, Seunghoon Lee2, Hyoungjin Kim1, and Won Kweon Jang1*
Current Optics and Photonics Vol. 6 No. 3 (2022 June) pp. 244-251
DOI: https://doi.org/10.3807/COPP.2022.6.3.244
Fig. 1 The static modulated Fourier-transform spectrometer during the reconstruction process and a magnified optical layout for its optical-path difference. (a) Schematic view of the static modulated Fourier-transform spectrometer consisting of a modified Sagnac interferometer. S, source; SD, source driver; M1, fixed mirror; M2, displaced mirror; BS, beam splitter; FL, focusing lens; D, onedimensional detector; CI, computer interface; SI, sample interferogram; TM, transfer-function matrix of the spectrometer; RS, reconstructed spectrum. (b) Magnified optical layout near the one-dimensional detector array.
Keywords: Interferometer, Reconstruction, Spectrometry, Static modulation
OCIS codes: (000.4430) Numerical approximation and analysis; (070.4790) Spectrum analysis;(120.3180) Interferometry; (300.6300) Spectroscopy, Fourier transforms
Abstract
We introduce a spectral reconstruction method to enhance the spectral resolution in a static modulated Fourier-transform spectrometer. The optical-path difference and the interferogram in the focal plane, as well as the relationship of the interferogram and the spectrum, are discussed. Additionally, for better spectral reconstruction, applications of phase-error correction and apodization are considered. As a result, the transfer function of the spectrometer is calculated, and then the spectrum is reconstructed based on the relationship between the transfer function and the interferogram. The spectrometer comprises a modified Sagnac interferometer. The spectral reconstruction is conducted with a source with central wave number of 6,451 cm−1 and spectral width of 337 cm−1. In a conventional Fourier-transform method the best spectral resolution is 27 cm−1, but by means of the spectral reconstruction method the spectral resolution improved to 8.7 cm−1, without changing the interferometric structure. Compared to a conventional Fourier-transform method, the spectral width in the reconstructed spectrum is narrower by 20 cm−1, and closer to the reference spectrum. The proposed method allows high performance for static modulated Fourier-transform spectrometers.
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[Editor's Pick] Current Optics and Photonics Vol. 6 no. 2 (2022 April)
Highly Birefringent Slotted-porous-core Photonic Crystal Fiber with Elliptical-hole Cladding for Terahertz Applications
Yong Soo Lee1, Soeun Kim2 *, and Kyunghwan Oh1 **
Current Optics and Photonics Vol. 6 No.2 (2022 April) pp. 129-136
DOI: https://doi.org/10.3807/COPP.2022.6.2.129
Fig. 1 Transverse cross section of the proposed photonic crystal fiber (PCF) design, and the extended view of the slotted porous core.
Keywords: High birefringence, Photonic crystal fiber, Terahertz
OCIS codes: (060.2280) Fiber design and fabrication; (060.5295) Photonic crystal fibers; (260.1440) Birefringence
Abstract
We propose a photonic crystal fiber (PCF) with a slotted porous core and elliptical-hole cladding, for high birefringence in the terahertz regime. Asymmetry in the guided mode is obtained mainly by using arrays of elliptical air holes in the TOPAS® polymer cladding. We investigate the tradeoff between several structural parameters and find optimized values that can have a high birefringence while satisfying the single-mode condition. The optical properties in the terahertz regime are thoroughly analyzed in numerical simulations, using a full-vector finite-element method with the perfectly-matched-layer condition. In an optimal design, the proposed photonic crystal fiber shows a high birefringence of 8.80 × 10−2 and an effective material loss of 0.07 cm−1> at a frequency of 1 THz, satisfying the single-mode-guidance condition at the same time. The proposed PCF would be useful for various polarization-management applications in the terahertz range.