Size tolerance analysis of a 4X4 tapered multimode interference coupler in a silicon-on-insulator structure

Size tolerance of a 4X4 general interference tapered multimode interference (MMI) coupler in a silicon-on-insulator (SOI) structure is investigated by means of a 2-D finite difference beam propagation method (2D-FDBPM), together with an effective refractive index method (EIM). The results show that the tapered multimode interference coupler exhibits relatively larger size tolerance when light is launched from the edgeport than from midport, though it has much better output power uniformity when light is launched from midport. Besides that, it can reduce the device length greatly. The 4X4 general interference tapered MMI coupler has a slightly larger size tolerance compared with a conventional straight multimode interference coupler. (C) 2003 Society of Photo-Optical Instrumentation Engineers.

Silicon-on-insulator based 2 x 2 multimode interference coupler with large tolerance

We demonstrate a type of 2 x 2 multimode interference 3 dB coupler based on silicon-on-insulator. The fabrication tolerance was investigated by the effective index method and the guide mode method. The devices with different lengths were fabricated and near-held output images were obtained. Tolerances to width, length and etch depth are 2, 200 and 2 mum, respectively. The devices show a uniform power distribution.

Principle of the moving-mirror-pair interferometer and the tilt tolerance of the double moving mirror

A novel type of interferometer, the moving-mirror-pair interferometer, is presented, and its principle and properties are studied. The new interferometer is built with three flat mirrors, which include two flat moving mirrors fixed as a single moving part by a rigid structure and one flat fixed mirror. The optical path difference (OPD) is obtained by the straight reciprocating motion of the double moving mirror, and the OPD value is four times the physical shift value of the double moving mirror. The tilt tolerance of the double moving mirror of the novel interferometer is systematically analyzed by means of modulation depth and phase error. Where the square aperture is concerned, the formulas of the tilt tolerance were derived. Due to the novel interferometer's large OPD value and low cost, it is very applicable to the high-spectral-resolution Fourier-transform spectrometers for any wavenumber region from the far infrared to the ultraviolet. (C) 2008 Optical Society of America.

Immune Responses to Six Synthetic Peptides of Capsid Protein Immune Responses to Six Synthetic Peptides of Capsid Protein

Many B cell epitopes within p24 of human immunodeficiency virus type 1 (HIV-1) were identified, while most of them were determined by using murine monoclonal antibodies reacting with overlapping peptides of p24. Therefore these epitopes may not represent the actual epitopes recognized by the HIV-1 infected individuals. In the present study, immune responses of 67 HIV-1 positive sera from Yunnan Province, China to five peptides on p24 of HIV-1 and one of HIV-2 were analyzed. All of 67 sera did not recognize peptide GA-12 on HIV-1 and peptide AG-23 on HIV-2, which indicated that GA-12 was not human B cell epitope and AG-23 did not cross-react with HIV-1 positive serum. Except 13 sera (19.4%), all remaining sera did not recognize peptides NI-15, DR-16, DC-22 and PS-18, which indicated that these four peptides represented B cell linear epitopes of HIV-1 p24 in some HIV-1 infected individuals but not the immuno-dominant epitopes in most individuals. Cellular & Molecular Immunology. 2005;2(4):289-293.

Tolerance analysis for incident angle of volume phase holographic grating used in optical channel performance monitor

Transmission Volume Phase Holographic Grating (VPHG) is adopted as spectral element in the real-time Optical Channel Performance Monitor (OCPM), which is in dire need in the Dense Wavelength -division-multiplexing(DATDM) system. And the tolerance of incident angle, which can be fully determined by two angles: 6 and (p, is finally inferred in this paper. Commonly, the default setting is that the incident plane is perpendicular to the fringes when the incident angle is mentioned. Now the situation out of the vertical is discussed. By combining the theoretic analysis of VPHG with its use in OCPM and changing 6 and (0 precisely in the computation and experiment, the two physical quantities which can fully specify the performance of VPHG the diffraction efficiency and the resolution, are analyzed. The results show that the diffraction efficiency varies greatly with the change of 6 or (p. But from the view of the whole C-band, only the peak diffraction efficiency drifts to another wavelength. As for the resolution, it deteriorates more rapidly than diffraction efficiency with the change of (p, while more slowly with the change of theta. Only if \phi\less than or equal to+/-1degrees and alpha(B) -0.5 less than or equal to theta less than or equal to alpha(B) + 0.5, the performance of the VPHG would be good enough to be used in OCPM system.

Alterations of immune functions induced by 12C6+ion irradiation in mice

Purpose: To estimate the biological risks to the immune system of the type of space radiation, 12C6+, encountered by cosmonauts during long-term travel in space. Materials and methods: The Kun-Ming strain mice were whole-body irradiated by 12C6+ ion with 0, 0.01, 0.05, 0.075, 0.2, 0.3, 0.5, 0.75, 1 or 2 Gy, at a dose rate of 1 Gy/min. At 35 days after irradiation, the thymus and spleen weights were measured, the natural killer (NK) cells activity of spleen was determined by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT), and the interferon-gamma (IFN-gamma) levels in serum and thymus were detected with enzyme-linked immunosorbent assays (ELISA). Results: The results showed that the thymus weight, IFN-gamma levels in serum and the activity of splenic NK-cells had significantly increased at a dose of 0.05 Gy. With further dose increase, the weight of spleen continued to increase but the weight of thymus, IFN-gamma level and NK-cells activity declined. Conclusions: These results suggest that the dose of 0.05 Gy irradiation has a stimulatory effect on mouse immunity; this effect declined with increasing dose.