Tieying Guo

Switchable multi-wavelength fiber ring laser based on a compact in-fiber Mach-Zehnder interferometer with photonic crystal fiber

Switchable multi-wavelength fiber ring laser with an in-fiber Mach-Zehnder interferometer incorporated into the ring cavity serving as wavelength-selective filter at room temperature is demonstrated. The filter is formed by splicing a section of few-mode photonic crystal fiber (PCF) and two segments of single mode fiber (SMF) with the air-holes on the both sides of PCF intentionally collapsed in the vicinity of the splices. By adjusting the states of the polarization controller (PC) appropriately, the laser can be switched among the stable single-, dual- and triple-wavelength lasing operations by exploiting polarization hole burning (PHB) effect.

Design of broadband nearly-zero flattened dispersion highly nonlinear photonic crystal fiber

We propose a new structure of broadband nearly-zero flattened dispersion highly nonlinear photonic crystal fiber (PCF). Through optimizing the diameters of the first two inner rings of air-holes and the GeO2 doping concentration of the core, the nonlinear coefficient is up to 47 W-1 km-1 at the wavelength of 1.55 \mum and nearly-zero flattened dispersion of \pm 0.5 ps/(nm km) is achieved in the telecommunication window (1460-1625 nm). Due to the use of GeO2-doped core, this innovative structure can offer not only a large nonlinear coefficient and broadband nearly-zero flattened dispersion but also low leakage losses.

High negative dispersion and low confinement loss photonic crystal fiber

A novel design of high negative dispersion and low confinement loss photonic crystal fiber (PCF) was proposed. The PCF designed has a high dispersion of -1120 ps/nm/km and a very low confinement loss of 1.01*1 10-6 dB/km at 1.55 mum.

Design of highly nonlinear photonic crystal fibers with flattened dispersion over S+C+L wavelength bands

Highly nonlinear fibers with nearly zero flattened dispersion over a wide band range has very wide applications in future high-capacity, all-optical networks. Because of its flexibility of structure design and much larger index contrast between the core and effective cladding than the conventional fibers, photonic crystal fibers (PCFs) are becoming to be an attractive candidate to form this kind of highly nonlinear fibers. Based on quantitative analysis on the effect of the difference of hole-sizes between the first ring and the others, and the effect of Ge-doped concentration in the core region on the PCFs dispersion curve, a new way to design PCF with high nonlinear coefficient and nearly zero flattened dispersion is proposed. Based on this, a PCF is designed, which has dispersion values between ±0.8ps/nm/km over S+C+L wavelength bands, and the dispersion slope of 0.005ps/nm2/km, nonlinear coefficient of 46.6W-1km-1 at 1.55μm.

Two-mode photonic crystal fiber interferometer for temperature and strain sensing

A compact in-line interferometer is demonstrated by splicing a piece of two-mode photonic crystal fiber (TPCF) between two segments of single mode fiber (SMF). The TPCF is completely homemade and carefully simulated by finite element method based on the real cross section. It is firstly verified that the interference occurred between LP01 and LP11even modes and the period of the interference pattern was inversely proportional to the length of TPCF. The temperatures and strain induced interference pattern shifts with sensitivities of −43pm/°C and −0.62pm/µε are experimentally monitored.

Analysis of mode coupling in the dispersion compensating photonic crystal fiber

The mode coupling in the dispersion compensating dual-core photonic crystal fiber is numerically investigated by the full-vector finite element method (FEM) with transparent boundary condition (TBC). The dependence of the phase-matching wavelength, the confinement loss, the effective mode area and the dispersion on the refractive index of the doped inner core, the diameter of air holes and the pitch is demonstrated. The dispersion value as large as -1426 ps/(nm -km), the effective mode area, 80 μm2 and confinement loss, 1.86×10-6 dB/m at λ=1.55μm are obtained.

Compact Mach-Zehnder interferometer based on photonic crystal fiber and its application in switchable multi-wavelength fiber laser

The compact Mach-Zehnder interferometer is proposed by splicing a section of photonic crystal fiber (PCF) and two pieces of single mode fiber (SMF) with the air-holes of PCF intentionally collapsed in the vicinity of the splices. The depedence of the fringe spacing on the length of PCF is investigated. Based on the Mach-Zehnder interferometer as wavelength-selective filter, a switchable dual-wavelength fiber ring laser is demonstrated with a homemade erbiumdoped fiber amplifier (EDFA) as the gain medium at room temperature. By adjusting the states of the polarization controller (PC) appropriately, the laser can be switched among the stable single-and dual -wavelength lasing operations by exploiting polarization hole burning (PHB) effect.

Reverse design of the SMF-PCF F-P cavity

In this paper, we report a new F-P cavity based on single mode fiber and multimode PCF. The PCF has been analyzed by the digital image processing and the FEM in order to obtain its effective refractive index and propagation constants. Then optical characteristics of the F-P cavity based on this PCF are numerical analyzed which provide a theoretical basis for the reverse design of the SMF-PCF F-P Cavity. The practice of fabricating SMF-PCF cavity based on this theory has been carried out and the experimental results and theoretical results were consistent.

A novel single-polarization single-mode photonic crystal fiber coupler

A vectorial finite element method is adopted to investigate this novel single-mode single-polarization (SPSM) photonic crystal fiber coupler which has asymmetric dual-core and two lines of enlarged air holes. we demonstrate that the SPSM region of the designed fiber can be more than 250nm wide for a set of optimized air-hole parameters and show that the width of the SPSM region could change slightly by little adjustment of the large inner air holes. The coupling length between the odd and even x-polarization modes are also investigated through fine-tuning the large and small air-hole diameters.

Study of the highly dispersive dual-core photonic crystal fiber with large mode area

The very high dispersive dual-core photonic crystal fiber is analyzed by the full-vector finite element method. The dependence of the phase-matching wavelength (PMW) and the full width at half-maximum (FWHM) on the refractive index of the doped inner core, the diameter of air holes and the hole pitch is demonstrated. The dispersion value is as large as -1427 ps/(nm km) and the effective mode area of the fundamental mode, 82.06 um2 are obtained.