Triple-core Photonic Crystal Fiber Research Articles

Study of Vector Bending Sensor in Various Configurations

A triple-core photonic crystal fiber (TCPCF) vector bending sensor has been introduced to study geometric parameter changes. The TCPCF shows a linear relationship between effective refractive index and input wavelength near 1.55µm. An asymmetrical geometry has been proposed for sensing both the direction and amplitude of the bend. The geometry of fiber creates an asymmetrical refractive index profile that leads to shifts in light speed in different fiber sections during the bend. The finite element method is used to study all sensor structures. The variation of the distance between cores, air hole diameter, and the angle between the side cores are studied. This sensor's need for precise and complex fabrication techniques is one of their challenges. Another challenge the design of these types of sensors faces is calibration for different environments and fabrication methods after fabrication is finished.

Role of structural asymmetry on the delivery of all-optical logical binary half adder in an asymmetric triple core photonic crystal fiber

This article explores the influence of structural asymmetry on the delivery of all-optical logical binary half adder function through triple-core photonic crystal fiber. For the proposed aim, the study considers different configurations of symmetric as well as asymmetric triple-core photonic crystal fiber involving optical guiding cores arranged in a planar and triangular fashion. The role of geometrical asymmetry is investigated by considering an asymmetric triple core photonic crystal fiber with a minor variation in one of the guiding core radii. Through the extinction ratio calculations, with suitable input signal combinations and control signal power, the half adder operation is demonstrated via logic outputs. The obtained results show the significant role of geometrical asymmetry indicated by the variation in the extinction ratios for the individual configurations. However, the half adder operation is found to be robust even in the presence of considerable geometrical asymmetry, with a significant figure of merit. Apart from this, a minor shift in the control signal phase is also observed between symmetric and asymmetric configurations for delivering logic gates based on the half adder function.

Tunable C-band and L-band multi-wavelength erbium-doped fiber ring laser based on a triple-core photonic crystal fiber with polarization-dependent loss

A tunable C-band and L-band multi-wavelength erbium-doped fiber laser (MW-EDFL) based on a novel fiber filter is proposed and experimentally demonstrated. The fiber filter is composed of a segment of triple-core photonic crystal fiber (TCPCF) and a segment of multi-mode fiber (MMF) between single mode fibers, which is inserted into the ring cavity of MW-EDFL as tuning component and wavelength selector. Based on the axial strain response of fiber filter, a tunable single-, dual- and triple-wavelength laser can be obtained with the tunable range of 19.58 nm, 10.34 nm, 6.84 nm, respectively. Meanwhile, the side-mode suppression ratio of lasing output is higher than 50 dB and the 3 dB linewidth is 0.026 nm for single wavelength lasing. Moreover, the lasing outputs are proved to be very stable at room temperature with the maximum wavelength shift of 0.06 nm and power fluctuation of 0.96 dB. Such a MW-EDFL with relatively simple structure and easy preparation has wide applications in important fields such as medicine, military, communication, and sensing.

High Performance Tunable Dual-Wavelength Erbium-Doped Fiber Laser Implemented by Using Tapered Triple-Core Photonic Crystal Fiber

Based on tapered Triple-Core Photonic Crystal Fiber (TCPCF), a high performance tunable Dual-Wavelength Erbium-Doped Fiber Laser (DW-EDFL) is proposed and experimentally demonstrated. The mode-coupling among three cores of TCPCF appears periodically and becomes further enhanced in tapered TCPCF, which are beneficial to form a filter to select lasing wavelength. A series of tapered TCPCFs with different taper lengths are fabricated and inserted into tunable DW-EDFL as filters. Multiple groups of tunable dual-wavelength lasing outputs are achieved by using the tapered TCPCF filter with a waist diameter of 126 μm. The maximum tunable range can reach up to 14.36 nm and the side mode suppression ratio of all lasing outputs are above 52 dB. In addition, the tunable single- and triple-wavelength lasers are also obtained. The tunable single-wavelength laser has an excellent linear response to strain and can be applied to realize a high-sensitivity strain sensor with the highest strain sensitivity of -13.1 pm/μe.

Using Mode Coupling Mechanism in Symmetrical Triple-Core Photonic Crystal Fiber for High Performance Strain Sensing

Basing on the mode coupling mechanism of symmetrical triple-core photonic crystal fiber (STCPCF), a highly sensitive strain sensor is proposed and experimentally demonstrated. Particularly, the triple-cores are arranged in an equilateral triangle on the pure silica host STCPCF. As a result, the coupling coefficient among the triple-cores of the STCPCF can increase as the fiber stretches. Moreover, the proposed sensor is designed by monitoring the wavelength shift of the coupling output spectrum. The experimental results show that the maximum strain sensitivity can be as high as -29.8 pm/με, which outperforms most of mode interference theory based fiber sensors. In addition, the strain sensitivity can be predicted by using mode-coupling mechanism in triple-core fiber. Theoretical results reveal that the sensitivity can be further improved up to -58.15 pm/με by optimizing the fiber structure parameters. Finally, the experimental results also show a high repeatability and stability, and a low temperature-strain cross-sensitivity of the proposed sensor.

Logic gates based all-optical binary half adder using triple core photonic crystal fiber

This study presents the implementation of an all-optical binary logic half adder by employing a triple core photonic crystal fiber (TPCF). The noteworthy feature of the present investigation is that an identical set of TPCF schemes, which demonstrated all-optical logic functions in our previous report, has revealed the ability to demonstrate the successful half adder operation. The control signal (CS) power defining the extinction ratios of the output ports for the considered symmetric planar and triangular TPCFs is evaluated through a numerical algorithm. Through suitable CS power and input combinations, the logic outputs are generated from extinction ratios to demonstrate the half adder operation. The results obtained display the significant influence of the input conditions on the delivery of half adder operation for different TPCF schemes considered. Furthermore, chloroform filled TPCF structures demonstrated the efficient low power half adder operation with a significant figure of merit, compared to that of the silica counterpart.

Impact of structural asymmetry on the efficiency of triple-core photonic crystal fiber for all-optical logic operation

We investigate the nonlinear dynamics and steering performance of structurally asymmetric triple-core photonic crystal fiber (ATPCF) for the accomplishment of efficient all-optical logic gates. We study two kinds of ATPCF, one with planar and the other with triangular core setting. The effective mode indices are obtained through the finite element method. The dynamics and steering characteristics of ATPCF are numerically explored via coupled nonlinear Schrödinger equations. The extinction ratios for the various logic gate operations are determined in the presence of suitable control signal. ATPCFs are found to demonstrate efficient logic gate operation; in addition, they highlight the practical issue of geometrical tolerance in PCF design.

Incomplete coupling triple-core photonic crystal fiber sensors for micro-bending angle detection

We demonstrate a flexible, high-sensitivity and low-cost optical fiber transducer to detect the micro-bending angle. The sensor uses a triple-core photonic crystal fiber. Based on a traditional triple-core photonic crystal fiber, large air holes are placed in the left and right cores around the central core, which causes the power among the three cores be incompletely coupled. Beams with a wavelength of 1550 nm are launched into the two side cores simultaneously. The optical power difference between the two side cores changes with the micro-bending angle. Coupling characteristic and beam propagation analysis of the micro-bending sensor are performed. The simulation results show that the optical power difference has a good linear relationship with the micro-bending angle in the range from 0° to 0.4°, and this sensor allows highly accurate micro-bending angle detection. The sensitivity of the micro-bending angle sensor can reach 0.421 62 W/deg.

Triple-core collinear and noncollinear plasmonic photonic crystal fiber couplers

Numerical analysis of single and multiple gold nanowires embedded in triple cores arranged in collinear and noncollinear configurations in photonic crystal fibers (PCFs) is reported. A full-vectorial finite element method is used to achieve coupling characteristics of plasmonic PCF couplers for both x and y polarizations. It is demonstrated numerically that the PCF plasmonic couplers exhibit polarization-independent tunable broadband filter characteristics that can be tuned according to the diameter of the embedded gold rod(s).

Realization of All-Optical Logic Gates in a Triangular Triple-Core Photonic Crystal Fiber

We propose an all-optical logical gate based in a triple-core photonic fiber crystal operating with two ultrashort fundamental soliton pulses of 100 fs, with pulse amplitude modulation in the modality of amplitude shift keying (PAM-ASK) with binary amplitude modulation. In particular, we examine the performance of a triple-core PCF coupler to execute two-input logical functions. The pulse propagation is modelled by an extended nonlinear Schroedinger equation including the terms associated with the anomalous group-velocity dispersion (GVD) and the third-order dispersion (β3), as well as the nonlinear effects of self-phase modulation (SPM), cross-phase modulation (XPM), self-steepening, and intrapulse Raman scattering (IRS) in a lossless configuration. Our results indicate the possibility of getting logical operations by controlling the phase difference between the input pulses.

Nonlinear coupling in triangular triple-core photonic crystal fibers

We report on a numerical analysis of the nonlinear coupling characteristics in triangular triple-core photonic crystal fibers (TTC-PCFs) by using coupled mode theory. The results show that the coupling of the TTC-PCFs exhibit more excellent power selectivity than that of the dual-core PCF and sharper optical switching and coupling-band with lower critical power are implemented in asymmetric TTC-PCF. By adjusting the parameters of the TTC-PCF structure and length, a coupling-band power controlled with better flatness will be obtained, in which more than 90% input power can be transferred. These results maybe offer a new possibility for application fields including optical switching, pulse shaping and pulse compressing.

Nonlinear inter-core coupling in triple-core photonic crystal fibers

We have developed a coupled-mode theory to describe light propagation in triple-core photonic crystal fibers (PCFs) in the nonlinear regime. The propagation equations including nonlinearities have been solved analytically. The nonlinear coupling for symmetric and asymmetric fibers is modeled for different coupling and nonlinear parameters. We investigate nonlinear inter-core coupling experimentally with a single high intensity pump beam. Optical switching of a signal beam in the presence of a control pump beam at a different wavelength is also demonstrated. The self-phase modulation (SPM) parameter gamma in the triple-core PCF studied is determined.

Polarization dependence of the inter-core coupling in triple-core photonic crystal fibers

We investigate both theoretically and experimentally the polarization dependence of the inter-core coupling in triple-core photonic crystal fibers (PCFs). The coupled-mode equations including polarization are developed and solved. The ordinary and extraordinary components of the coupling coefficients are determined through experiments. Inter-core coupling is found to be stronger for light polarized along the line of the three cores. Effects from asymmetric coupling are also observed.

Decoupling and asymmetric coupling in triple-core photonic crystal fibers

We systematically investigate the intercore coupling in triple-core photonic crystal fibers (PCFs). Coupled-mode equations are developed and solved analytically in the linear approximation. We derive the eigenmodes in triple-core PCFs, in particular we model the decoupling mode and test its stability against perturbations. The coupling coefficients and the coupling length are determined experimentally and found to agree extremely well with the calculated results. We describe the propagation of light in triple-core PCFs for different launching conditions.