Loss-Modulation-Based Wavelength-Range Shifting of Tunable EDF Ring Laser with Cascaded-Chirped Long-Period Fiber Grating for Temperature Measurement.

Koken Fukushima,Atsushi Wada,Satoshi Tanaka,Fumihiko Ito,Manuel Guterres Soares

doi:10.3390/s21072342

Koken Fukushima, Atsushi Wada + Show 3 more

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https://doi.org/10.3390/s21072342

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Abstract

A novel tunable Erbium-doped fiber ring laser (EDFRL) with a cascaded-chirped long-period fiber grating (C-CLPG) as a wavelength selection filter is proposed from the viewpoint of the sensor use, in which a variable optical attenuator (VOA) is employed as an intracavity loss modulator to change the oscillation wavelength region so that the resultant tuning wavelength range is widened. In the demonstrative experiment for temperature measurements, oscillation over the wavelength range of 12.85 nm (1557.62~1570.47 nm), which is more than three times range of the previously presented laser and is equivalent to 64 °C in terms of temperature change, was achieved, while a single-wavelength oscillation was maintained. In addition, a practical technique for realizing a temperature measurement by combining with the VOA control is also discussed.

Highlights

It is noted that the spectrum, the channeled spectrum of the the oscillation output(~29 is usually obtained at oscillation one of the peaks as of well the as channeled spectrum, cascaded-chirped longperiod fiber grating (C-chirped LPGs (CLPGs))
We have proposed an oscillation wavelength range shifting technique based on an intracavity loss modulation in a tunable and switchable Erbium-doped fiber ring laser (EDFRL) with a C
We have proposed an oscillation wavelength range shifting technique based on an intracavity loss modulation in a tunable and switchable EDFRL with a C-CLPG

Summary

Introduction

Fiber gratings are fabricated by inducing a periodic refractive index modulation along the optical fiber, and are classified into two types based on their grating period: fiber Bragg grating (FBG) and long-period fiber grating (LPG). The FBG, which is inscribed typically with a submicron grating period, couples a forwardpropagating core mode with a backward-propagating one at the Bragg wavelength, and serves as a narrow-band reflection filter [1]. The LPG, which is inscribed with a grating period ranging from tens to hundreds of μm, couples a forward-propagating core mode with several codirectional cladding modes at their resonant wavelengths and provides a relatively wide and nonreflective band-rejection filter [2]. LPG sensors utilize coupling characteristics between the core mode and the cladding modes, which makes them sensitive to strain, pressure, temperature, and the environmental refractive index [3]

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