Intermodal coupling of supermodes in a twin-core photonic crystal fiber and
its application as a pressure sensor

Abstract

In this paper, we experimentally demonstrated the fabrication and hydrostatic pressure characteristics of a twin-core photonic crystal fiber (TC-PCF). Mode couplings in the TC-PCF for x- and y-polarizations were analyzed simultaneously using group effective index of guiding modes. The output spectrum of the TC-PCF was modulated due to the combined couplings of the two polarizations. To the best of our knowledge, it is the first time to measure hydrostatic pressure through the dual-polarization mode coupling in a TC-PCF. The measured sensitivity of the pressure sensor was -21 pm/MPa. The length of the TC-PCF used for pressure measurement was 20 cm, which is much shorter than pressure sensor based on PM-PCF, and does not require any external polarizing components, meaning that it is a good candidate for compact pressure sensor.

Ultrahigh birefringence index-guiding photonic crystal fiber and its application for pressure and temperature discrimination

“…The measured propagation loss of the PCF is ∼0.2 dB∕m. The splicing loss with SMF28 is ∼2.1 dB using a technique similar to that used in [17,18], which is in accordance with the value in [19]. Note that two air holes at the outer ring are missing, because two capillaries were broken during stacking.…”

“…The fabrication process illustrated in Fig. 1 is similar to the fabrication method we conducted previously for a twin-core PCF [17]. Capillaries with diameter of 1.6 mm were first drawn from a silica tube that has an outer diameter of 44 mm and inner diameter of 17.6 mm.…”

Ultrahigh birefringence index-guiding photonic crystal fiber

“…The fabrication process is similar to the fabrication method conducted by us previously for a twin-core PCF [6]. Capillaries with diameter of 1.6 mm were firstly drawn from a silica tube that has an outer diameter of 44 mm and inner diameter of 17.6 mm.…”

Compressible fiber optic micro-Fabry-Pérot cavity with ultra-high pressure sensitivity

“…Various types of fiber optic pressure sensors have been demonstrated to fulfill specific pressure applications, including fiber Bragg gratings (FBGs) [1], photonic crystal fiber (PCF) devices [2] and interferometers [3,4], and the pressure sensitivity achieved is typically on the order of −10 pm/Mpa. Among above mentioned configurations, the pressure sensors that are based on Fabry-Pérot (FP) interferometer have shown promising results for static and dynamic pressure measurements [5,6], as well as other physical and chemical parameter detections such as temperature [7], strain [8,9] and refractive index [10].…”

“…Among above mentioned configurations, the pressure sensors that are based on Fabry-Pérot (FP) interferometer have shown promising results for static and dynamic pressure measurements [5,6], as well as other physical and chemical parameter detections such as temperature [7], strain [8,9] and refractive index [10]. The FP interferometers can achieve extremely high sensitivity and flexibly demodulated in the wavelength domain [3,4] and frequency domain [6,8], or simply use light intensity detection [11].…”