The shape of the grooves of a diffraction grating can be designed to take advantage of total internal reflection. We demonstrated the effectiveness of the total internal reflection (TIR) grating numerically for the bulk optic case and experimentally for the integrated optic case. The results indicated that the efficiency of the retro- diffracted order is enhanced by about 10 dB when the TIR grating design is used in place of an echelle grating with no facet metalization. We demonstrate that a TIR grating can be integrated on a chip to demultiplex 120 optical channels that are transmitted in a dense wavelength division multiplexing (DWDM) application. The wavelengths of the channels had a 0.29 nm spacing and were within the 1550 nm wavelength band for DWDM applications.
Concave gratings traditionally have been based on the Rowland circle design. A grating design formalism is discussed here that allows greater flexibility than the Rowland circle design. With this formalism, a wavelength division demultiplexer (WDM) may be designed so that the passbands for the output waveguides may be tuned after the demultiplexer has been fabricated. The design considerations for these devices are discussed and are different from the design considerations for Rowland circle gratings. The design of the grating facets is discussed in detail. Experimental results show that facets using light at an angle of incidence that is nominally 45 degrees can become highly efficient due to total internal reflection.
This paper analyzed productivity change of four sizes of dairy production in China in 2006—2010 using the Bootstrap-Malmquist indices. The result showed that the productivity, technological efficiency and technological progress of different sizes of dairy production all progressed and was negative to scale, backyard and small-scale rearing had higher growth rate, technological progress was the main reason of productivity progress. At present, we should pay attention to the backyard and small-scale rearing, and further strengthen the role of technological progress on dairy production of China.
A 120-channel WDM demultiplexer was fabricated by etching a concave grating into a SiO/sub 2/-SiON-SiO/sub 2/-Si slab waveguide. The grooves of the grating reflected light by two instances of total internal reflection. The device was suitable for demultiplexing wavelength channels in the 1530-1565-nm range with a 0.29-nm (36 GHz) channel spacing. Each channel had a spectral width (full width at half maximum) of about 0.18 nm. The fiber-to-fiber insertion loss was between -20 dB and -30 dB for most channels. The loss was predominantly due to waveguide absorption and increased dramatically for wavelengths below 1539 nm.
The Nineteenth National Congress of the Communist Party of China put forward the full implementation of performance management. Thus, the importance of fiscal performance evaluation has risen to a new height. The performance evaluation index of fiscal expenditure is an important prerequisite for performance management. The performance evaluation index of fiscal expenditure policy refers to the assessment tool to measure the degree of achievement of fiscal expenditure policy performance goals. This paper study the performance evaluation indexes of fiscal expenditure policy from its basic framework and basic principles, categorization the indicators of fiscal expenditure performance evaluation system; make the evaluation of performance of fiscal expenditure more clearly. The construction of the performance evaluation index system of fiscal expenditure plays a very important role in evaluating the economy, efficiency and effectiveness of fiscal expenditure.
Considering the importance that pulverized coal can timely ignite or not to the safe and economy operation of power plant boiler, an extensive matter-element evaluation method is proposed based on the matter-element concept and the extensive set theory. On the basis of building evaluation level indicators and evaluation model, by calculating extensive correlation degree between the state parameters with the ignition timeliness of pulverized coal and every evaluation rank, we can decide the ignition timeliness of pulverized coal in boiler is timely or not according to correlation degree. Finally the effectiveness, accurateness and practicability of the method using in evaluating the ignition of pulverized coal have been proved through an example.
Wavelength division multiplexing (WDM) is a useful technology for increasing the information capacity of optical systems. Multiplexers and demultiplexers are key elements in WDM systems. Planar integrated demultiplexers based on concave gratings and arrayed waveguide gratings are attractive both for mass production and the ability to support large number of channels. Here, we report out preliminary results on concave grating demultiplexer with 90 channels and 0.3 nm channel spacing.
Based on the latest method of total factor productivity research at home and abroad, this paper uses the panel data of 17 Chinese life insurance companies from 2007 to 2016 to estimate the total factor productivity of Chinese insurance companies using the Malmquist index analysis method of DEA model. The measurement method is a regression analysis of several factors affecting the total factor productivity of Chinese insurance companies. The empirical results show that among the micro factors, the asset-liability ratio, asset turnover, operating efficiency and company size have a significant impact on the total factor growth rate of Chinese life insurance companies. Among the macro factors, GDP growth rate, inflation rate and unemployment rate have a significant impact on the total factor growth rate of Chinese life insurance companies.
A 60-channel WDM demultiplexer based on a concave grating with 0.144 nm channel spacing in the 1.5 µm wavelength region was fabricated. The demultiplexer comprises SiO2/SiON/SiO2 waveguides on Si and an individual channel has a full width at half maximum spectral width of 0.09 nm.
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