Yoshinori Namihira

Proposal for Highly Nonlinear Dispersion-Flattened Octagonal Photonic Crystal Fibers

A highly nonlinear photonic crystal fiber (HNL-PCF) based on an octagonal structure with isosceles triangular-latticed cladding is proposed for the telecommunication window. The finite-difference method with anisotropic perfectly matched boundary layer is used to investigate the guiding properties. It is demonstrated that it is possible to design a simple HNL low-loss dispersion-flattened PCF with a nonlinear coefficient of the order 27 W-1km-1 at a 1.55-mum wavelength. According to simulation, ultraflattened dispersion of 0 plusmn 0.5 ps/nm/km is obtained in a 1.46- to 1.66-mum wavelength with low confinement losses less than 0.06 dB/km in the entire band of interest.

Numerical Investigation of Octagonal Photonic Crystal Fibers with Strong Confinement Field

In this paper, the confinement loss of octagonal photonic crystal fibers (PCFs) with an isosceles triangle lattice of air-holes are numerically investigated. Taking into account the confinement loss, the mode field diameter (MFD), the effective area (A eff ) and the chromatic dispersion of octagonal PCFs are calculated, compared to conventional hexagonal PCFs. It is found from confinement loss and MFD results that the octagonal PCFs can confine the field strongly than the hexagonal PCFs due to the different air filling fraction. Moreover, it is shown that the octagonal PCFs are obtained not only positive but also negative larger dispersion values and smaller A eff values compared to the hexagonal PCFs.

Tailoring Dispersion and Confinement Losses of Photonic Crystal Fibers Using Hybrid Cladding

We present a hybrid cladding photonic crystal fiber (PCF) for shaping nearly zero ultraflattened dispersion and low confinement losses in a wide range of wavelengths. The finite difference method with anisotropic perfectly matched boundary layer is used to investigate the guiding properties. It has been shown theoretically that it is possible to obtain nearly zero ultraflattened dispersion of 0 plusmn0.25 mups/nm/km in a wavelength range of 1.44 to 2.0 mum with low confinement losses less than 0.005 dB/km within the entire band of interest from a five-ring hybrid cladding PCF.

Broadband Dispersion Compensating Octagonal Photonic Crystal Fiber for Optical Communication Applications

We numerically report the design of a modified octagonal photonic crystal fiber (M-OPCF) for broadband dispersion compensation covering the C and L communication bands, i.e., wavelengths ranging from 1530 to 1625 nm. It was shown that the proposed broadband compensating PCF can be designed to simultaneously exhibit a high negative dispersion coefficient and a relative dispersion slope (RDS) close to that of a conventional single-mode optical fiber (SMF). From our results, it was found that the M-OPCF has a large negative dispersion [-226 to -290 ps/(nmkm)] over the C- and L-bands, and an RDS close to that of an SMF of about 0.0034 nm-1. In addition to this, the effective dispersion, residual dispersion, confinement loss, and polarization properties of the proposed PCF are also reported and discussed.

Novel Square Photonic Crystal Fibers with Ultra-Flattened Chromatic Dispersion and Low Confinement Losses

This study proposes a novel structure of index-guiding square photonic crystal fibers (SPCF) having simultaneously ultra-flattened chromatic dispersion characteristics and low confinement losses in a wide wavelength range. The finite difference method (FDM) with anisotropic perfectly matched layers (PMLs) is used to analyze the various properties of square PCF. The findings reveal that it is possible to design five-ring PCFs with a flattened negative chromatic dispersion of 0-1.5 ps/(nm.km) in a wavelength range of 1.27 μm to 1.7 μm and a flattened chromatic dispersion of 0±1.15 ps/(nm.km) in a wavelength range of 1.25 μm to 1.61 μm. Simultaneously it also exhibited that the confinement losses are less than 10 -9 dB/m and 10 -10 dB/m in the wavelength range of 1.25 μm to 1.7 μm.

Highly nonlinear dispersion-flattened square photonic crystal fibers with low confinement losses

A new simple structure of an index-guiding highly nonlinear dispersion-flattened square photonic crystal fiber (HNDFSPCF) with low confinement losses is proposed. The results reveal that it is possible to design five-rings HNDF-SPCFs with a flattened dispersion of 0.43 ps/(nm·km), low dispersion slope of -0:02 ps/(nm2·km), low confinement loss of approximately 103 dB/m, and a large nonlinear coefficient of approximately 35W-1 km-1 at 1.55 μm. It is also observed that the confinement loss is less than 10-1 dB/m in the wavelength range of 1.2 –1.7 μm.

Dynamic polarization fluctuation characteristics of optical fiber submarine cables under various environmental conditions

Polarization fluctuation characteristics of optical-fiber submarine cable under 8000-m-deep sea environmental conditions, optical-fiber submarine cable coupling under periodic variable tension, and cable performance during and after installation, are presented. As a worst case, it is demonstrated that the maximum frequency spectrum of polarization fluctuation is less than 200 Hz under dynamic composite stress states. It is found that the polarization fluctuation of the optical-fiber submarine cable coupling changes linearly with periodic variable tensile forces. It is confirmed that the power spectrum of polarization fluctuations are less than 50 approximately 60 Hz, and the maximum power spectra are between 5 and 10 Hz during the cable installation within a maximum cable tension of 18 kN (1.8 tons) and the cable laying speed of 3.5 knots, respectively. >

Experimental study on visible light communication based on LED

Abstract A visible light communication system using white light emitting diode (LED) has been proposed and demonstrated, in which the transmitter and receiver of visible light communication have been designed and realized. In the experiment, the illumination of the receiving surface in different distance between LED and photodiode receiver has been tested, and the effect of background light has been considered. The experiment results show that the data transmit bit rate can be achieved at 111.607 kbit/s when the average indoor illumination is 40 lx, with the communication distance of our visible light system at 1.5 m.

Fiber Length Dependence of Polarization Mode Dispersion Measurements in Long-Length Optical Fibers and Installed Optical Submarine Cables

Using an interferometric detection technique with AC modulation for searching the interference fringe signal, a highly accurate polarization mode dispersion (PMD) measurement system with 0.003 ps/m resolution has been developed. A comparison of this PMD measurement with the other wavelength scanning PMD method is described. Fiber length dependence of PMD measurements in long-length optical fibers is presented. Based on the square root of fiber length dependence of PMD confirmed in this measurement, the maximum PMD in the cascaded lOOkm-long optical fibers and installed 60 km-long optical submarine cabled fibers are less than 0.1 ps/j/km. Also, the statistical point of view of the PMD measurements in the optical fibers is presented.

Fault Location for Branched Optical Fiber Networks based on OFDR Technique Using FSF Laser as Light Source

A new fault location method for passive branched optical fiber networks is proposed, which bases on OFDR technique using FSF laser source, and the fault in fiber branches are located according to the heterodyne detection.