Optical wavelength measuring device using absorption-type optical fiber-based multiple optical fiber filter module, optical sensor system having the same, and optical measurement method

An optical fiber sensor system comprising:

• a light source to generate an input light;
• an optical fiber sensor installed in a measurement target, and the optical fiber sensor to receive the input light from the light source and to output a signal light corresponding to a physical quantity change by a measurement target;
• and
• an optical wavelength measuring device to detect the signal light outputted from the optical fiber sensor and to calculate a physical quantity applied to the optical fiber sensor,
• wherein the optical wavelength measuring device includes:
• a first optical splitter to split the signal light provided from the optical fiber sensor into a first split light and a second split light,
• a first optical detection unit to detect the first split light outputted from the first optical splitter, wherein the first optical detection unit includes a second optical splitter to split the first split light into a first reference light and a first analysis light, a first optical detector to detect the first reference light, a first optical fiber filter installed on an optical path of the first analysis light, and a second optical detector to detect the first analysis light passing through the first optical fiber filter,
• a polarization controller installed on an optical path of the second split light outputted from the first optical splitter, and the polarization controller to control a polarization state of the second split light,
• a second optical detection unit to detect the second split light which is polarization- controlled by the polarization controller, wherein the second optical detection unit includes a third optical splitter to split the second split light polarization-controlled by the polarization controller into a second reference light and a second analysis light, a third optical detector to detect the second reference light, a second optical fiber filter installed on an optical path of the second analysis light, and a fourth optical detector to detect the second analysis light passing through the second optical fiber filter, and
• a calculation module to calculate an optical wavelength of the signal light according to a physical quantity applied to the optical fiber sensor based on information detected by the first optical detection unit and the second optical detection unit,
• wherein the physical quantity is calculated by measuring a shift of a center wavelength of the signal light due to environmental changes applied to the optical fiber sensor, and
• wherein the calculation module compensates for a polarization fluctuation in the information detected by the first optical detection unit by using the information detected by the second optical detection unit, by calculating the shift of the center wavelength based on a ratio of a sum of optical intensities of the first reference light and the second reference light to a sum of optical intensities of the first analysis light and the second analysis light.

An optical measurement method comprising:

• an input light outputting step of generating, by a light source, an input light to an optical fiber sensor installed in a measurement target;
• a first light splitting step of receiving the input light from the light source, outputting a signal light corresponding to a physical quantity applied to the optical fiber sensor, and splitting the signal light into a first split light and a second split light using a first optical splitter;
• a first light receiving step of detecting, using a first optical detection unit, the first split light split in the first light splitting step, wherein the first light receiving step includes:
• a second light splitting step of splitting the first split light into a first reference light and a first analysis light through a second optical splitter,
• a first light detecting step of detecting the first reference light split in the second light splitting step by using a first optical detector,
• a first filtering step of passing the first analysis light split in the second light splitting step through a first optical fiber filter, and
• a second light detecting step of detecting the first analysis light passing through the first optical fiber filter by using a second optical detector;
• a polarization control step of controlling a polarization state of the second split light split in the first light splitting step by using a polarization controller;
• a second light receiving step of detecting the second split light using a second optical detection unit after the polarization control step, wherein the second light receiving step includes:
• a third light splitting step of splitting the second split light into a second reference light and a second analysis light through a third optical splitter,
• a third light detecting step of detecting the second reference light split in the third light splitting step by using a third optical detector,
• a second filtering step of passing the second analysis light split in the third light splitting step through a second optical fiber filter, and
• a fourth light detecting step of detecting the second analysis light passing through the second optical fiber filter by using a fourth optical detector;
• and
• a wavelength and physical quantity calculating step of calculating the physical quantity applied to the optical fiber sensor using a calculation module by calculating an optical wavelength of the signal light based on information detected in the first light receiving step and the second light receiving step,
• wherein the physical quantity is calculated by measuring a shift of a center wavelength of the signal light due to environmental changes applied to the optical fiber sensor, and
• wherein the calculation module compensates for a polarization fluctuation in the information detected by the first optical detection unit by using the information detected by the second optical detection unit, by calculating the shift of the center wavelength based on a ratio of a sum of optical intensities of the first reference light and the second reference light to a sum of optical intensities of the first analysis light and the second analysis light.