Suspended-core Microstructured Fiber Research Articles

Four-wave mixing fits ultrasensitive refractive index sensing with suspended-core microstructured Fiber

An ultrasensitive refractive index sensor based on the four-wave mixing in a suspended-core microstructured fiber (SC-MOF) is proposed. It presents that, due to much power penetration into the air holes of the SC-MOF, the refractive index (RI) sensitivity is up to 2.43 × 105 nm/RIU for the produced idler wave of the four-wave mixing in SC-MOF. The RI responses of idler wave and signal wave are analyzed as pump wavelengths locate in the normal dispersion region and anomalous dispersion region, respectively. The simulation results show that, if the pump wavelength locates in normal dispersion region and the idler wave is used for wavelength-encoded demodulation, it would be more appropriate for RI sensing. The influence of incident power on RI sensitivity, power fluctuation induced RI measurement error and sensing quality are also analyzed. It is demonstrated that moderate incident power must be selected, and pump wavelength away from transition point would be beneficial for RI measurement stability.

Single-polarization operation in suspended-core microstructured fibers

We present the design and investigation of a single-polarization suspended-core fiber with an elliptical core consisting of crossed rectangular-shaped dielectric strips. By optimizing the fiber configuration parameters, single-polarization single-mode transmission with a bandwidth of 400nm can be obtained. Also, the power fraction in air of the x-polarization fundamental mode is relatively high, which facilitates its applications in high precision sensors.

Suspended-core microstructured fiber for refractometric detection of liquids.

A silica suspended-core microstructured optical fiber sensor for detection of liquids, operating at 1550nm, is analyzed. The sensing principle is based on the evanescent wave overlap into a tested analyte, which is filled via capillary forces into the cladding holes. Validations for analytes in the refractive index range of 1.35-1.43 are carried out with liquid-analyte-filling-length limits being studied both theoretically and experimentally. We prove, for the first time to our knowledge, that an extreme sensitivity of 342.86dB/RIU and resolution of 4.4×10-5 can be achieved. This sensor represents a high-quality alternative for applications requiring a facile, low-cost solution.

Efficient Supercontinuum Sources Based on Suspended Core Microstructured Fibers

We fabricate uniform silica microstructured optical fibers (MOFs) having very simple geometry with only three rings of air holes in order to generate efficient supercontinuum (SC). The fabricated MOFs possess suspended core with comparatively larger pitch and are the most active component in a SC source. We use the suspension factor as a design parameter which significantly influences the nonlinear and dispersion properties of the MOFs. It is experimentally shown that our fabricated MOFs generate efficient SC both in femtosecond and picosecond pumping domain. We also numerically model the nonlinear dynamics for SC sources in order to identify the nonlinear processes and illustrate the spectral broadening mechanisms.

Nonlinear optical devices based on suspended-core microstructured optical fibers

Suspended-core microstructured optical fibers are employed in lasers that generate ultrashort pulses and supercontinuum generators. It is demonstrated that a femtosecond fiber laser based on the ytterbium-doped microstructured fiber generates pulses with a duration of 95 fs at a wavelength of 1045 nm and a mean power of 5 mW in the absence of additional compression. Supercontinuum is generated in tapered microstructured fibers with suspended core in the wavelength interval 400–1400 nm. Suspended-core micro-structured fibers may serve as promising elements for nonlinear optical devices due to specific waveguide characteristics, relative simplicity of manufacturing, and variable optical properties.

Fourth-order cascaded Raman shift in AsSe chalcogenide suspended-core fiber pumped at 2 μm

Cascaded Raman wavelength shifting up to the fourth order ranging from 2092 to 2450 nm is demonstrated using a nanosecond pump at 1995 nm in a low-loss As(38)Se(62) suspended-core microstructured fiber. These four Stokes shifts are obtained with a low peak power of 11 W, and only 3 W are required to obtain three shifts. The Raman gain coefficient for the fiber is estimated to (1.6±0.5)×10(-11) m/W at 1995 nm. The positions and the amplitudes of the Raman peaks are well reproduced by the numerical simulations of the nonlinear propagation.