Baoxue Chen

Production of biodiesel fuel from triglycerides and alcohol using immobilized lipase

Transesterification reaction was performed using triglycerides and short-chain alcohol by immobilized lipase in non-aqueous conditions. The long-chain fatty acid ester, which is the product of this reaction, can be used as a diesel fuel that does not produce sulfur oxide and minimize the soot particulate. Immobilized Pseudomonas fluorescens lipase showed the highest activity in this reaction. Immobilization of lipase was carried out using porous kaolinite particle as a carrier. When methanol and ethanol were used as alcohol, organic solvent like 1,4-dioxane was required. The reaction could be performed in absence of solvent when 1-propanol and 1-butanol were used as short-chain alcohol. The activity of immobilized lipase was highly increased in comparison with free lipase because its activity sites became more effective. Immobilized enzyme could be repeatedly used without troublesome method of separation and the decrease in its activity was not largely observed.

Fabrication of an As2S8 stripe waveguide with an optical stopping effect by exposure to ultraviolet irradiation

Amorphous As2S8 chalcogenide glass is shown to undergo changes in the refractive index upon exposure to ultraviolet light. This phenomenon is employed to fabricate an As2S8 stripe waveguide, which is shown to be an effective guided mode device with a useful switching functionality based on the photo-optical effect.

Optimized design of polarization-independent and temperature-insensitive broadband optical waveguide coupler by use of fluorinated polyimide.

A statistically optimized design method suitable for a polariation-independent and temperature-insensitive broadband waveguide coupler is proposed. By use of this method, a fluorinated polyimide waveguide 3-dB waveguide coupler for 1490 to approximately 1610 nm application is designed by optimizing polarization and temperature fluctuation. The validity of the design is verified through simulation based on the three-dimensional beam propagation method (3D-BPM), which revealed a coupling ratio of 50 +/- 0.8% in a 120-nm bandwidth in the temperature range -10 to 40 degrees C for both orthogonal polarizations.

Photo-induced refractive index change of amorphous tin-doped As2S8 films and its application to strip waveguide fabrication

The amorphous chalcogenide glass Sn1As20S79 is demonstrated to undergo permanent changes in refractive index on irradiation with ultraviolet light. The refractive properties of this material and the effect of annealing at temperatures below the glass transition temperature are investigated in detail. An Sn1As20S79 strip waveguide is fabricated using this photoinduced refractive index change, and the device is shown to function as expected with good propagation characteristics for the 632.8 nm guided mode.

Photo- and thermally induced changes in the refractive index and film thickness of amorphous As2S8 film

Changes in the refractive index and thickness of amorphous As2S8 semiconductor film are observed under illumination, annealing–illumination, and annealing-illumination cycles. Properties of the As2S8 film are measured using techniques of prism coupler, x-ray diffraction spectra and Raman spectra. After light illumination the refractive index change in an as-deposited As2S8 film is one order of magnitude greater than that of an annealed As2S8 film, corresponding to ∼0.06 and ∼0.0057, respectively. Photoexpansions with a change in the relative film thickness of the as-deposited and annealed As2S8 film are nearly −3.5% and −2.1%, respectively, which exhibit the photodensification. The full reversibility of the photoinduced refractive index change is claimed on an annealed As2S8 film sample.

Optimized design of temperature-insensitive optical waveguide coupler with 120-nm bandwidth using fluorinated polyimide

Method for designing optimized temperature-insensitive optical waveguide couplers by use of fluorinated polyimide is presented. Based on measured temperature and dispersion characteristics of fluorinated polyimide, a 3-dB waveguide coupler with a 120-nm bandwidth with minimal temperature variance is designed and verified through simulation based on three-dimensional beam propagation. The coupling ratio of the theoretical device is 50 +/- 0.7% in the waveband 1490 to approximately 1610 nm and the temperature range -10 to approximately 40 degrees C.

Nonlinear optical properties of As20S80 system chalcogenide glass using Z-scan and its strip waveguide under bandgap light using the self-phase modulation

Optical nonlinearities in the undoped As20S80, low doped P2As20S78 and Sn1As20S79 chacogenide glasses are investigated by using Z-scan method. These experiments show that at 1064 nm the figure of merit (FOM) for As20S80 is ∼1.02, while for Sn1As20S79 increases to ∼1.42, and for P2As20S78 decreases to ∼0.83. These resulted data indicate the addition of Sn in As20S80 system chalcogenide glass can enhance FOM due to creating narrow energy gaps. In addition, the self-phase modulation (SPM) width experiment for Sn1As20S79 strip waveguide displays that the full width half maximum (FWHM) of spectral width increases approximately 0.8 nm under the induction of bandgap light, meaning that the bandgap light can induce to enhance its optical nonlinearity with the nonlinear refractive index of n2≅5.27×10−14 cm2/W.

The Sensing Structure Optimization of Planer Optical Waveguide With Fermi Refractive Index

The essay theoretically analyses the Fermi distribution of gradient refractive index waveguide cladding mode absorption spectrum characteristics, it also analyses the structure of the sensitivity within cladding absorption associated with the waveguide parameters, test sensitivity is associated with the waveguide mode and the waveguide parameters, especially with the waveguide layer thickness which is very sensitive to correlation. The analysis of results was confirmed by the Experiment of Guided Wave Loss Test. In the experiment the interaction ratio is measured, with waveguide in corresponding thickness and the mode in maximal interaction ratio is used as a sensing device which is used as a waveguide circuit with double-sample serial structure for measuring the liquid-clad absorption loss. The results show a very significant linear relationship between solution concentration and refractive indexs imaginary part which characterizes the solution cladding absorption feature. By using this sensing relationship, the concentrations C. I. Pigment Green7 solution samples 13 with kinds of different concentrations have been measured. The standard deviation between the measured values and the actual values is less than 0.07%.

Fabrication of an amorphous As2S8 stripe waveguide and its optical stopping effect

Amorphous As2S8 chalcogenide glass is shown to undergo changes in refractive index upon exposure to ultraviolet (UV) light. As2S8 film properties are studied, which were measured with testing techniques of prism coupler, x-ray diffraction spectrum and Raman spectra. It is found that the refractive index increases and the thickness decreases after UV light irradiation. The visible optical absorption spectra show that photo-darkening does not exist in the As2S8 film. Based on the study of these phenomena, the UV light irradiation technique is presented and employed for fabricating an As2S8 stripe waveguide, which is shown to be an effective guided mode device with a useful switching functionality based on the photo-optical effect, such as an all-optical attenuator.

Automatic waveguide-fiber coupling system based on a multiobjective evolutionary algorithm

A method for the automated alignment of optical waveguides and fibers based on a multiobjective evolutionary algorithm is proposed. This algorithm reduces the number of parallel operations considerably compared to previous automation schemes. The automated alignment of a single-core input fiber with a channel waveguide and a single-core output fiber is completed using this system in less than 3 min. The alignment of a single-core input fiber with a 1x8 splitter coupler and an eight-core output fiber array is completed in less than 10 min. These results demonstrate the effectiveness of the proposed scheme for automated waveguide alignment, substantially outperforming previous automatic alignment methods.