Sandwiched photonic crystal fiber for dispersion compensation over the S + C + L + U wavelength bands.

We numerically investigated a sandwiched photonic crystal fiber (S-PCF) based on triangular lattice air holes that can be used for broadband dispersion compensation. By adjusting two layers of air holes diameter in the cladding, the S-PCF performs a large negative dispersion curve that can compensate for the dispersion of a standard single-mode fiber (SMF). The kappa value of the proposed PCF is also consistent with that of the SMF at the wavelength of 1.

A Photonic crystal fiber with large effective refractive index separation and low dispersion.

A photonic crystal fiber (PCF) structure with a ring-core and 5 well-ordered semiellipse air-holes has been creatively proposed. Through a comparison between the structures with a high refractive index (RI) ring-core and the structure without, it conclude that a PCF with a high RI ring-core can work better. Schott SF57 was elected as the substrate material of ring-core.

Simultaneous measurement of optical rotation dispersion and absorption spectra for chiral substances.

We present a new method based on optical null methods for simultaneously measuring the optical rotatory dispersion (ORD) and absorption spectra of chiral substances. The optical rotation angle at a specific wavelength can be obtained from the optical nulls of the Malus curves with and without the sample. We use the optical nulls of the two curves as benchmark points and the readings to the right of the benchmark points by a certain angular offset to eliminate the influence of the analyzer on the light intensity and obtain the absorbance of the chiral substance at a specific wavelength.

Theoretical proposal of a low-loss wide-bandwidth silicon photonic crystal fiber for supporting 30 orbital angular momentum modes.

We propose a novel four-ring hollow-core silicon photonic crystal fiber (PCF), and we systematically and theoretically investigate the properties of their vector modes. Our PCF can stably support 30 OAM states from the wavelength of 1.5 μm to 2.

Equivalent model optimization with cyclic correction approximation method considering parasitic effect for thermoelectric coolers.

As thermoelectric coolers (TECs) have become highly integrated in high-heat-flux chips and high-power devices, the parasitic effect between component layers has become increasingly obvious. In this paper, a cyclic correction method for the TEC model is proposed using the equivalent parameters of the proposed simplified model, which were refined from the intrinsic parameters and parasitic thermal conductance. The results show that the simplified model agrees well with the data of a commercial TEC under different heat loads.

Novel method for determination of optical rotatory dispersion spectrum by using line scan CCD.

A novel method is presented for rapid measurement of optical rotatory dispersion (ORD). Light passes through a polarizer, sample and analyzer, to a transmission grating that disperses the collimated light beam. A step-motor rotating stage controlled by a digital signal processor changes the analyzer orientation.

Research of optical rotation measurement system based on centroid algorithm.

An optical rotation measurement system based on digital signal processor, modulated laser, and step motor rotating stage is established. Centroid algorithm featured fast and simple calculation is introduced to process light signals with or without sample to obtain the optical rotating angle through the step difference between two centroids. The system performance is proved experimentally with standard quartz tubes and glucose solutions.

Three-parameter error analysis method based on rotating coordinates in rotating birefringent polarizer system.

We propose error analysis using a rotating coordinate system with three parameters of linearly polarized light--incidence angle, azimuth angle on the front surface, and angle between the incidence and vibration planes--and demonstrate the method on a rotating birefringent prism system. The transmittance and angles are calculated plane-by-plane using a birefringence ellipsoid model and the final transmitted intensity equation is deduced. The effects of oblique incidence, light interference, beam convergence, and misalignment of the rotation and prism axes are discussed.

Generation of cylindrically symmetric modes and orbital-angular-momentum modes with tilted optical gratings inscribed in high-numerical-aperture fibers.

Optical fiber with high numerical aperture (NA) can efficiently relieve the degeneracy of higher-order linearly polarized modes. The degeneracy relief is investigated in two types of high-NA fibers, i.e.

Mode add/drop multiplexers of LP₀₂ and LP₀₃ modes with two parallel combinative long-period fiber gratings.

Two parallel combinative long-period fiber gratings (LPFGs) can convert the fundamental core mode LP(01) in a single-mode fiber (SMF) into one desired higher order core mode LP(0m) in a few-mode fiber (FMF), in the process of which one specific cladding mode acts as a medium coupled from one fiber to another. Different LP(0m) modes can be obtained by controlling the grating period of LPFG in FMF to meet the phase matching condition. In this article we focus on the design and analyses of LP(02) and LP(03) mode add / drop multiplexers (MADMs).

Correction of image distortions in endoscopic optical coherence tomography based on two-axis scanning MEMS mirrors.

A two-axis scanning microelectromechanical (MEMS) mirror enables an optical coherence tomography (OCT) system to perform three-dimensional endoscopic imaging due to its fast scan speed and small size. However, the radial scan from the MEMS mirror causes various distortions in OCT images, namely spherical, fan-shaped and keystone distortions. In this paper, a new method is proposed to correct all of three distortions presented in OCT systems based on two-axis MEMS scanning mirrors.

Endoscopic swept-source optical coherence tomography based on a two-axis microelectromechanical system mirror.

A microelectromechanical system (MEMS) mirror based endoscopic swept-source optical coherence tomography (SS-OCT) system that can perform three-dimensional (3-D) imaging at high speed is reported. The key component enabling 3-D endoscopic imaging is a two-axis MEMS scanning mirror which has a 0.8×0.

Improving the accuracy of optical rotation measurement based on optical null methods by curve-fitting.

An optical rotation measuring system using optical null methods is set up. The system is based on a step-motor rotating stage structure and a modulated laser, which both are controlled by digital signal processor. By introducing a curve-fitting method, the optical rotation angle is obtained from the step difference between the crossed positions in light signal curves with or without sample.

[Determination of optical parameters in thin films by transmittance spectra].

The high tin-doped SiO2 films prepared by CVD will bring some crystals, but sol gel can control the accurate chemical component of the films. So it can produce high tin-doped materials. In the present paper, the tin-doped SiO2 films were prepared by a sol gel dip-coating process on glass substrates at concentrations of 66 mol% and 75 mol%.

[Structure changes of lead silicate glasses induced by UV laser irradiation].

The structure changes of lead silicate glasses induced by UV laser irradiation were studied by UV-visible spectra and electron spin resonance (ESR). The Urbach energies of lead silicate glasses exposed to the 266 nm UV laser increased. This implied that the disorder of the lead silicate glasses was increased.