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1

Firmware development for the fibre-optic seismometer based on FOG

Kamiński Marek, Tylman Wojciech, Jabłoński Grzegorz, Kotas Rafał, Amrozik Piotr, Sakowicz Bartosz, Jaroszewicz Leszek R.

Opto-Electronics Review

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2024

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Vol. 32, No. 2

art. no. e150179

EN

The main goal of the article is to present the concept of using a simulation environment when designing an advanced fibre-optic seismometer (FOS) using a field-programmable gate array (FPGA) computing system. The first part of the article presents the advanced requirements regarding the FOS principle of operation, as well as the measurement method using a closed-loop operation. The closed-loop control algorithm is developed using the high-level language C++ and then it is synthesised into an FPGA. The following part of the article describes the simulation environment developed to test the operation of the control algorithm. The environment includes a model of components of the measurement system, delays, and distortions in the signal processing path, and some of the measurement system surroundings. The article ends with a comparison of simulation data with measurements. The obtained results are consistent and prove correctness of the methodology adopted by the authors.

2

Wavelength-switchable fiber ring laser using chirped Moiré fiber grating combined with Sagnac loop interferometr

Lu S., Zhang M., Feng S.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 1b

11--14

EN

A simple, cost-effective and switchable five-wavelength fiber ring laser based on a chirped moiré fiber grating (CMFG) and a wavelengthtunable Sagnac loop interferometer (FSI) filter is proposed and experimentally demonstrated. To serve as wavelength selective element, the CMFG possesses excellent comb-like filtering characteristics, and its fabrication method is easy and flexible. The usage of the FSI filter helps remove the high-cost optical circulator and improve the output performance of optical signal-to-noise ratio.

PL

Zaproponowano i przedstawiono eksperymentalnie prosty, tani światłowodowy laser żyroskopwy z przełączanymi pięcioma długościami fali. Zastosowano siatkę dyfrakcyjną z efektem mory ze skomprymowanego włókna (CMFG) oraz, w pętli strojenia, filtr z interferometrem z pętlą Signac’a (FSI). Wykorzystana jako element selektywny, ustalający długość fali, siatka CMFG zapewnia doskonałą, grzebieniową charakterystykę filtru, ponadto metoda jej wytwarzania jest łatwa i elastyczna. Wykorzystanie filtru FSI pomaga obniżyć koszt układu i zapewnia na wyjściu dobry stosunek sygnał/szum.

3

Theory of nonlinear Sagnac effect

Eliseev P. G.

Opto-Electronics Review

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2008

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Vol. 16, No. 2

118-123

EN

A nonlinear wave interaction is considered as a technique to increase the rotation sensitivity of the ring laser. The gyroscopic scale factor K is calculated in an active laser gyro with a dispersive medium. K is in reverse proportion to the group index n* = n + vdn/dv of the medium. In a monolithically-integrated GaAs ring laser, the value K ~ 5000 is obtainable (radius ~ 1 cm) in a linear case. In the presence of a strong wave, the dynamic nonlinear anomalous dispersion can provide an increase of K by 10-100 times in the vicinity of critical points where n* passes zero. An expression of K is derived for the nonlinear Sagnac effect. The nonlinear dispersion is discussed in terms of "slow/fast" light.