npsm 새물리 New Physics : Sae Mulli

pISSN 0374-4914 eISSN 2289-0041


Research Paper

New Phys.: Sae Mulli 2020; 70: 810-815

Published online September 29, 2020

Copyright © New Physics: Sae Mulli.

Fiber-optic Reflection-type Filter with Optically Variable Spectral Bandwidths

Ju Ha KIM, Seung Seok LEE, Eun Seo CHOI*

Department of Physics, Chosun University, Gwangju 61452, Korea


Received: May 27, 2020; Revised: July 27, 2020; Accepted: July 31, 2020


We propose the fiber-optic reflection filter that can optically change the spectral bandwidths by using ytterbium-doped fiber Bragg gratings (Yb-FBGs). When 980-nm pump light is applied to the ytterbium-doped special optical fiber, the refractive index of the optical fiber core changes, and the central wavelength of fiber gratings shifts. To use this feature, we fabricated Yb-FBGs with lengths of 10 mm and 20 mm, and we measured the spectra for various applied current values of the pumping light. We implemented a fiber-optic reflection filter by using two Yb-FBG’s and measured its filter characteristics. The central wavelength of the 10-mm Yb-FBG was fixed by using a pump, and a variable light output was applied to the 20-mm Yb-FBG by using the other pump. Changes in the center wavelength and the bandwidth of the spectrum for the reflection filter according to the applied current of the other pump were observed. As a result of the measurement, the change rates of the center wavelength and the half width of the filter were about 0.60 pm/mA and about 0.05 pm/mA, respectively.~Development of various light sources and sensors may be possible by using the characteristics of a reflective filter capable of optically fine spectrum control.

Keywords: Yb-doped optical fiber, Yb-FBG, Variable bandwidths, Optical filter

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