Single-mode Photonic Crystal Fiber Research Articles

Splice Loss Investigation of Single-Mode Fiber and Photonic Crystal Fibers and Its Potential Refractometric Sensing Applications

Splice Loss Investigation of Single-Mode Fiber and Photonic Crystal Fibers and Its Potential Refractometric Sensing Applications

Mode-locked large-mode-area Er/Yb-doped fiber oscillator via nonlinear polarization evolution with enhanced mode suppression

We report a mode-locked Er/Yb-doped large-mode-area (LMA) fiber oscillator based on nonlinear polarization evolution (NPE), which utilizes a linear cavity primarily composed of polarization-maintaining (PM) fibers. The oscillator operates at 1.56 µm with a fundamental repetition rate of 34.47 MHz and has two output ports. One port can deliver high-quality soliton-like pulses with a pulse duration of 325 fs and an average power of 39.5 mW (corresponding to a pulse energy of 1.15 nJ). In contrast, the other port not only generates lower-quality complex pulses but also exhibits poorer short-term and long-term stability, likely due to cross-phase modulation effects. To the best of our knowledge, this is the first implementation of the NPE mode-locked technology in a PM-LMA Er/Yb-doped fiber oscillator at 1.55 µm which often suffers from poor self-starting mode-locking capabilities. This achievement is primarily attributed to the use of endlessly single-mode photonic crystal fibers, which effectively suppress higher-order modes in PM-LMA fibers.

Research on sensing characteristics of microfluidic sensor based on photonic crystal fiber

To address the challenges associated with sample injection into the air hole of photonic crystal fiber (PCF) and collimation, in this paper, we assemble a single-mode photonic crystal single-mode fiber structure sensor chip based on the Mach–Zehnder interference principle using microfluidic chip processing technology. The sensing principle is analyzed mathematically and the sensing characteristics are verified theoretically and experimentally. The temperature sensitivity of the sensor is −1.3325 nm °C−1, and the refractive index sensitivity is 1666.2 nm RIU−1. This structure solves the difficulty of filling and coupling PCFs. Furthermore, it introduces a novel research methodology for the design and assembly of high-performance biosensors based on PCFs.

Correction to: Design of graded-index-type photonic crystal fiber with uniform air hole diameter and its application to collimator for single-mode photonic crystal fiber

Correction to: Design of graded-index-type photonic crystal fiber with uniform air hole diameter and its application to collimator for single-mode photonic crystal fiber

A single-mode chalcogenide photonic crystal fiber for bending resistance with large mode area and wide bandwidth

A single-mode chalcogenide photonic crystal fiber for bending resistance with large mode area and wide bandwidth

Design of graded-index-type photonic crystal fiber with uniform air hole diameter and its application to collimator for single-mode photonic crystal fiber

Design of graded-index-type photonic crystal fiber with uniform air hole diameter and its application to collimator for single-mode photonic crystal fiber

Coupling of laser diode with cylindrical microlens fabricated on the tip of single-mode photonic crystal fiber: prediction of coupling optics by ABCD matrix

Abstract We report the theoretical prediction of the coupling optics involving a laser diode and photonic crystal fiber which contains on its tip cylindrical microlens. The analysis is based on relevant ABCD matrix formalism. Though photonic crystal fiber has very large single-mode region, we carry on the investigation for two commonly used wavelengths such as 1.3 µm and 1.5 µm. For the particular kind of photonic crystal having specific value of air filling ratio and hole pitch, we have optimized the distance of laser diode from the microlens in order to get maximum value of coupling efficiency for each value of radius of cylindrical microlens. Incidentally, we have got here maximum coupling efficiency to the extent of 86.99 % at the wavelength 1.3 µm when the radius of the cylindrical microlens is 8.5 µm and effective spot size of the fiber is 4.433909 µm. Further, the maximum efficiency becomes 91.78 % at 1.3 µm when the radius of the cylindrical microlens is 4.0 µm and effective spot size of the fiber is 1.859907 µm. It has been shown that wavelength 1.5 µm is not so coupling efficient like 1.3 µm. Moreover, it has been shown that with same set of relevant parameters, PCF is more coupling efficient compared to ordinary graded index fiber. Thus the present work generates scope for varying different photonic crystal fiber parameters and the wavelengths of source as well for enhancing the coupling efficiency. Accordingly, the present analysis will be extremely helpful for design of efficient coupler of this kind.

Low-loss chalcogenide microstructured optical fibers prepared by eliminating interfaces defects.

The loss of chalcogenide microstructured optical fibers (ChG-MOFs) is generally higher than that of step fibers, mainly due to the immature fiber preform preparation method and strong waveguide defect scattering. Chemical polishing is used to polish mechanically drilled preforms to prepare ChG-MOFs with low defect scattering. Firstly, the scattering loss caused by the defective layer of ChG-MOFs is studied theoretically and experimentally. Then, a single-mode photonic crystal fiber (PCF) was prepared to verify the effect of chemical polishing on reducing fiber loss. The experimental results show that the PCF average loss is reduced from more than 8 dB/m to less than 2 dB/m, and the minimum loss reaches 0.8 dB/m @ 2.7 µm. At the same time, the bending strength of the PCF after chemical polishing is also significantly improved.

Performance analysis of photonic crystal fiber structure based on different highly nonlinear materials

Generally, fiber with a large mode area is desired for fiber laser and beam delivery applications. But the use of these fiber types is restricted to linear optical applications due to the lower value of the nonlinear coefficient. This paper investigates a single material-based photonic crystal fiber (PCF) with improved optical characteristics, applicable for linear and nonlinear optics. The light propagation in the structure is explored by applying finite element solver-based COMSOL multiphysics software. Five nonlinear optical materials are utilized as background material to get the optimized material with high performance PCF. Using this PCF, the improved optical properties of PCF such as moderate effective mode area of 115.85 [Formula: see text], chromatic dispersion, confinement loss of 10[Formula: see text] dB/m, the nonlinear coefficient of 543W[Formula: see text]Km[Formula: see text], splicing loss of 2.013 dB, and numerical aperture are numerically analyzed. This single-mode PCF also shows the low bending loss for the bending radius of 7[Formula: see text]mm. The amended PCF structure is found to be suitable for high-power fiber laser, supercontinuum generation, wavelength conversion, and slow-light generation.

Design of Single-Polarized Single-mode Photonic Crystal Fiber Without Air Holes in the Cladding

This study proposes a novel single-polarized single-mode (SPSM) photonic crystal fiber (PCF) without air holes in the cladding, and the silicon nitride holes and air holes in the core of the PCF are staggered. Based on the full vector finite element method, the birefringence characteristics with different hole sizes have been discussed in detail, and a SPSM-PCF is achieved through optimizing the core structure. Moreover, the extinction ratio, effective refractive index, dispersion, confinement loss and nonlinearity of the PCF are analyzed. Simulation results show that the PCF can obtain a high birefringence value of 2.142 × 10−3 , a large negative dispersion of −2750 ps/(nm · km), a low confinement loss of 1.57 × 10−7dB/m and a high nonlinear coefficient of 90.5W−1 · km−1 at the wavelength of 1.55 μm. In this paper, the proposed structure has the properties of high birefringence and high negative dispersion, which can be used in fiber laser, optical fiber sensing, dispersion compensation and other fields.

Study the effect of Pitch size When the number of rings of the second air gaps on the dispersion profile of Photonic Crystal Fibers

The need for a fibre optics working in the visible part of the electromagnetic spectrum has led to the development of new kind of fibre optics called photonic crystal fibre (PCF).In this paper we have investigate the effect of the pitch distance Λ as a function of the wavelength for a single mode PCF. The results has indicated that for (Nr=2 , MNr=1 , Λ=1.2 , d/Λ=0.5) this design has a dispersion of (-37ps/nm/km) at λ=0.8µm and a dispersion of (-30 ps /nm/km) at λ=1.31µm and a dispersion of( 1.10ps/nm/km) at λ= 1.55µm .This design has a flat dispersion for a wavelength range of (0.95 µm, in addition to that, this model has (3ZDW) in the dispersion curve. P

High sensitivity trace carbon monoxide gas sensor based on endlessly single-mode photonic crystal fiber Sagnac interferometer

Abstract In this paper, a novel carbon monoxide (CO) gas sensor based on α-Fe2O3/MgO is presented and constructed. The endlessly single-mode photonic-crystal fibers (ESPCF) was sandwiched between the four-core fibers (FCF) to form the ESPCF-FCF-ESPCF structure, which was embedded it in the Sagnac loop to construct the Sagnac interferometer. The crystal structure, composition and morphology of α-Fe2O3/MgO sensing film were characterized by the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM), respectively. The results indicated that the α-Fe2O3/MgO sensing film was uniformly coated on the outside surface of two ESPCFs, with a thickness of about 1 μm. When these sensing films adsorbed CO, the monitoring wavelength showed blueshift and the maximum sensitivity was 99.42 pm/ppm. The response time and recovery time were respectively 90 s and 100 s respectively. The Sagnac fiber-optic sensor exhibt high sensitivity, good selectivity and strong stability, and it can effectively realize the monitoring of carbon monoxide.

Single-mode D-shaped photonic crystal fiber surface plasmon resonance sensor with open microchannel

Accessible microchannels that allow microscale fluid control and microparticle-filtering are promising tools for advanced biological and chemical sensing and analysis. To this end, we proposed a d-shaped photonic crystal fiber surface plasmon resonance sensor with open microchannel. The optical characteristics of the sensor were numerically investigated using the Finite Element Method and the fiber structure was then fabricated using a standard stack-and-draw method. The numerical results demonstrate that the d-shaped photonic crystal fiber can be applied as a sensor with wide refractive index detection range between 1.330 and 1.435, a maximum sensitivity of 28400 nm/RIU, finest resolution of 3.52 × 10−6 RIU, and maximum figure-of-merit of 592 RIU−1. The sensor operates in the single-mode regime, has good linearity range, requires simple fabrication, has high coupling efficiency with conventional single-mode fibers, and has low losses, making it a practical candidate for wide range of applications in chemical and biological testing.

175 W average power from a single-core rod fiber-based chirped-pulse-amplification system.

We report on a fiber-based chirped-pulse-amplification laser system with bulk transmission grating compression to a pulse duration of 357 fs, average power of 175 W, and pulse energy of 233μ J. The compressed pulse train has a beam quality factor M2 of 1.21. The power amplifier is based on a state-of-the-art single-mode photonic crystal rod-type ytterbium-doped fiber operating at 248 W of average power and a repetition rate of 750 kHz. The long-term stability of the laser system has been tested continuously for more than 4000 hours and shows no sign of transverse mode instability.

Mach-Zehnder interferometer comb filter for multi-wavelength mode-locked generation from erbium-doped fiber laser.

A picosecond pulse multi-wavelength erbium-doped fiber ring laser based on an optically switchable/tunable Mach-Zehnder interferometer (MZI) filter is proposed and experimentally demonstrated. The MZI configuration is constructed with two 3 dB couplers and two short pieces of endlessly single-mode photonic crystal fiber with different lengths in each arm. The combination of the MZI and a polarization controller (PC) acts as a selective comb filter and a mode-locking device. By adjusting the pump power or the first PC (PC1) state, the laser can emit up to 10 channels with a 20 nm tuning range (1530 to 1550 nm). Furthermore, by changing the PC1 condition, stable picosecond mode-locking generation with a repetition rate of 13.5 MHz is realized. To achieve wavelength spacing tunable multiple-channel laser emissions, the MZI is configured by incorporating a second PC (PC2) in one arm of the conventional MZI. Four channels of picosecond mode-locking pulses with a repetition rate of 11.6 MHz in the range of 1530-1550 nm are realized by carefully controlling the pump power and/or PC2 state. With the manipulation of intracavity birefringence through PCs with comb filtering via MZI, the proposed structure may be a potential tool in various photonics applications.

Single-mode eccentric-core D-shaped photonic crystal fiber surface plasmon resonance sensor

A single-mode eccentric-core D-shaped photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor is proposed and comprehensively investigated based on Finite Element Method (FEM). The critical properties of the sensor such as single mode regimes, beam spot size, and confinement losses are all tailored for more practical network-integrable PCF SPR sensor with high coupling efficiency using commonly used single-mode optical fibers. The sensor has analyte Refractive-Index (RI) detection range between 1.330 and 1.420 with maximum sensitivity of 21200 nm/Refractive-Index-Unit (RIU), maximum Figure-of-Merit (FOM) of 294 RIU−1, maximum resolution of 4.72 × 10-6 RIU for analyte refractive index change of 0.005 with the finest Full-Width at Half-Maximum (FWHM) of 29 nm, and a maximum confinement loss of 14 dB/cm. The sensor exhibits high linear response at low analyte RI regime between analyte index 1.330 and 1.370. The proposed sensor design can be fabricated using comparatively simpler stack-and-draw method which is based solely on standard circular glass capillaries and solid rods.

Epsilon negative-based, broadband single-polarization single-mode hollow core anti-resonant photonic crystal fiber.

A broadband single-polarization single-mode (SPSM) hollow core anti-resonant photonic crystal fiber (HC-ARPCF) is proposed and analyzed by the finite element method in this paper. The HC-ARPCF design consisted of outer semicircular cladding tubes and inner circular cladding tubes. The SPSM behavior is achieved through controlling the effective material absorption loss (EML) by loading epsilon negative (ENG) material in the selected semicircular cladding tubes. Optimization of the configuration parameters is conducted to yield a large loss difference (LD) between one of the two orthogonally polarized fundamental modes and all the other unwanted modes. Therefore, only one desired mode will exist after a proper propagation distance, i.e., SPSM guidance. Specially, the optimal design provides a 288 nm (from 1408 nm to 1676 nm and from 1680 nm to 1700 nm) bandwidth in terms of 40 dB/m minimum LD (MLD) and 168 nm (from 1452 nm to 1620 nm) bandwidth in terms of 100 dB/m MLD. Furthermore, this fiber also exhibits a large effective mode area and near-zero dispersion properties over the entire operation bandwidth. The proposed HC-ARPCF may find its applications in polarization maintaining and high-power laser systems.

Chirality parameter sensing based on surface plasmon resonance D-type photonic crystal fiber sensors.

We report a method to sense a surrounding chiral drug based on D-type single-mode photonic crystal fiber (PCF) sensors in this paper. The electromagnetic theory of surface plasmon resonance on metal-chiral drug structure is derived. The wave equation containing constitutive relations of a chiral drug is given and integrated into the finite element method to compute the effective refractive index, confinement loss, and plasmon resonance wavelength for a D-type PCF sensor immersed in the chiral drug. The effects of the chirality parameter on resonance behaviors are displayed. The wavelength sensitivities of the chirality parameter for the sensor changing with different kinds of metal film layers, side-polished depth, and thickness of metal film layer are calculated. The wavelength sensitivity can reach a maximum of 17,580 nm/chirality as the refractive index and chirality parameter of the drug are 1.36 and 0.08, respectively. Furthermore, simultaneous dual-parameter detection of the chirality parameter and refractive index is realized by using two different D-type PCF sensors with gold and silver metal film layers, respectively. This study may provide sufficient guidelines to the field of biochemical sensing.

Simulation and analysis of ultra-low material loss of single-mode photonic crystal fiber in terahertz (THz) spectrum for communication applications

Abstract This analysis represents a circular shape based cladding with two elliptical shape cores in photonic crystal fiber (PCF) for the terahertz (THz) range. Here, we present a single-mode photonic crystal fiber (SM-PCF) with five layers of circular shape of air holes (CAH) structure along with two layers of elliptical shape of air holes (EAH) core configuration in the center to decrease the different types of losses. For broad-band communications, our proposed SM-PCF is highly useful due to the obtaining of ultra-low effective material loss (UML) in the terahertz regime. Perfectly matched layers (PMLs) and finite element method (FEM) established on COMSOL Multiphysics software has been used to design this PCF fiber. Simulated outcomes show a particularly an UML deficit of 0.014 cm−1, power fraction in the core area (CA) and large effective area (EA) of 72%, and 5.90 × 10−8 m2 respectively at 1 terahertz (THz) frequency. Also, other aspects of optical fiber for THz signal banquet with confinement loss (CL), scattering loss (SL) and V-parameter have been calculated here. Moreover, our proposed SM-PCF shows single-mode propagation by V-parameter pointer over 0.80–3 THz frequency. So, we can say that our designed PCF fiber will be suitable for various effective communication areas at the terahertz (THz) spectrum.

Large mode area single mode photonic crystal fiber with ultra-low bending loss

A novel asymmetrical structure of Photonic Crystal Fibers (PCFs) has been proposed in this article. The first ring consists of three big air holes which can confine the propagating mode in the core region. The second ring consists of twelve doped rods with two different diameters which can decrease the difference of refractive index between the core and the cladding in order to provide the large mode area. The third ring consists of eleven air holes to help the higher-order-modes (HOMs) to leak out. The bending properties of proposed fiber are investigated by full vector finite element method with an anisotropic perfectly matched layer. The numerical results show that the effective mode area of the FM of the proposed fiber is as large as 595.02 μm2 with small bending radius of 10 cm at the wavelength of 1064nm. The bending loss of fundamental mode (FM) is 9.884×10−5dB/m, while large bending loss for the high-order mode (HOMs) is 14.685dB/m. Moreover, the loss ratio can reach 1.45×105which can realize the effective and stability single-mode operation. Therefore, the novel fiber has potential application in high-power fiber lasers.