Shanglin Hou

Bend Performance Analysis of Few-Mode Fibers With High Modal Multiplicity Factors

This paper presents a comprehensive and detailed investigation on the bend-induced characteristics of the most advanced few-mode fibers (FMFs) that allow one to multiply the capacity of single-mode fiber transmissions by a high factor (≥12), suitable for dense mode-division multiplexing (MDM) systems. To be specific, we numerically demonstrate how bend can affects the normalized propagation constant, modal field distribution, bend loss, and effective area of all supported spatial LP modes, for both the weakly coupled step-index (SI) 7-LP-mode fiber (adapted to weakly coupled MDM systems with a modal multiplicity factor of 12) and the trench-assisted graded-index (GI) low-differential-mode-group-delay 9-LP-mode fiber (adapted to strongly coupled MDM systems with a modal multiplicity factor of 15). Also presented are the empirical relations of normalized spatial density for the above two FMFs at different bend radii. Finally, for weakly coupled SI FMFs and GI low-DMGD FMFs, we reexamine their design strategy and scalability depicted in [4], from a unique perspective of bend performance.

Research on the controllable frequency octupling technology for generating optical millimeter-wave by external modulator

A novel scheme is proposed for frequency octupling mm-wave generation based on an integrated triple-parallel MZM without filter. Two kinds of redundant sidebands are well eliminated by adopting 90 degrees of the electric phase-difference about two sub Mach-Zehnder modulators (sub-MZMs), driven by radio frequency (RF) signal. Then bias of the third sub-MZM is tailored to get best signal. The results indicate that the radio frequency spurious suppression ratio (RFSSR) is as high as 38.3315 dB under the condition of conventional extinction ratio (30 dB). Moreover, optical sideband suppression ratio (OSSR) can reach as high as 61.22878 dB at ideal extinction ratio (100 dB). Compared with previous schemes, it not only optimizes the method but get high RFSSR in the conventional condition.

Design of an improved microstructure fibre for broadband dispersion compensation with low nonlinearity

A microstructure fibre for broadband dispersion compensation with low nonlinearity in a wide wavelength range centred at 1550 nm is designed. The effects of the number of air-hole rings, the air-hole diameters and the lattice pitch on both the dispersion property and nonlinear phenomenon are numerically described. The results indicate that the inner six air-hole rings have stronger impact on dispersion and nonlinearity. By adjusting the diameters of the fourth to sixth air-hole rings and the lattice pitch, the proposed microstructure fibre can compensate (to within 0.5%) the dispersion of 190 times of its length of a standard single-mode fibre with a low nonlinear coefficient over the entire 100 nm band centred at 1550 nm.

A polyatomic photonic crystal ring resonator and its application to the optical biochemical sensor

In this work, we propose a schematic design for the biochemical sensor, which is based on the polyatomic photonic crystal ring resonator (PCRR). Unlike with the conventional approach, the proposed PCRR is constituted by two different branching waveguides (WG), which are all in the same lattice direction but have different optical propagation properties due to the binary nature of the diatomic square lattice. Electromagnetic analysis via PWE and FDTD numerical techniques are employed to investigate the sensing performance and the results show that the proposed sensor can efficiently detect the small changes in the refractive index of sensing area.

Photonic generation of frequency quadrupling signal for millimeter-wave communication utilizing three parallel Mach-Zehnder modulators

In this work, we propose a new scheme of generating high quality frequency quadrupling signal for millimeter-wave wireless communication system. The frequency quadrupling scheme is achieved by using three parallel Mach-Zehnder modulators (MZMs) and an optical phase shifter. The first two MZMs are driven by the RF signals to operate at the maximum transmission point. The third MZM is operated with no RF signal and an extra π-phase difference is introduced for it by the optical phase shifter. The advantage of the proposed scheme is that the optical carrier and the fourth optical sideband can be suppressed simultaneously. The performance of proposed scheme is investigated theoretically and evaluated by simulations. Numerical results show that the radio frequency spurious suppression ratio (RFSSR) higher than 44.18 dB and the optical sideband suppression ratio (OSSR) higher than 21 dB can be obtained without optical filter when the extinction ratio (ER) of the MZM is 30 dB. The impact of the non-ideal RF driven voltage and phase difference of RF driven signal applied to the first two sub-MZMs on OSSR and RFSSR is also discussed and analyzed.

Simultaneous measurement of temperature and strain based on a fiber Bragg grating with cladding made of electro-optic crystal material

In this paper, a novel fiber Bragg grating (FBG) sensor which can measure the temperature and strain simultaneously is presented. The cladding layer of the proposed FBG sensor is made of a uniaxial crystal material (LiTaO3) and the electric field is applied on the 1/2 area of the sensor. The sensing performance was investigated by the coupled-mode theory and dual-wavelength method. We found that the strain sensitivity and the temperature sensitivity of the 1/2 area with no electric field are 0.841 pm/με and 14.31 pm/°C respectively. If the electric field is increased from 0 to 400×107 v/m, the temperature sensitivity of this device varies from 14.31 pm/°C to 14.12 pm/°C and its strain sensitivity varies from 0.841 pm/με to 0.850 pm/με. So, the obtained results demonstrate that the simultaneous measurement of temperature and strain can be achieved by using this scheme. The proposed sensor has potential applications in optical fiber sensing systems due to small size, high sensitivity and compatible with optical fiber.

Investigation on nonlinearity of optical fiber with uniaxial crystal material cladding

A fiber with cladding made of uniaxial anisotropic crystal material whose optical axis is parallel to the axis of fiber was proposed, and the nonlinear parameter γ of this kind of fiber was investigated theoretically. The ratio (k_cl) of the extraordinary to the ordinary ray index was introduced and the influence of parameter k_cl upon γ was examined by exact vector modes method. The calculated results indicate that the parameter k_cl has a strong impact on γ, and the parameter γ can be effectively modified through tailoring k_cl while keeping other parameters of fiber as constant.

Influence of air-hole rings on dispersion of microstructured fibers

The effects of the number of air-hole rings on dispersion property are numerically described. The results indicate that the inner six air-hole rings have stronger impact on dispersion and nonlinearity. By adjusting the diameters of the air-hole beyond the third ring, the proposed microstructured fiber can compensate (to within %0.5) the dispersion of 190 times of its length of standard single mode fiber with low nonlinear coefficient over the entire 100 nm band centered at 1550 nm.