Thermally enhanced responsivity in an all-silicon optical power monitor based on defect-mediated absorption

We demonstrate a high responsivity all-silicon in-line optical power monitor by using the thermal effect to enhance the quantum efficiency of defect-mediated absorption at 1550 nm.The doping compensation technique is utilized to increase the density of lattice defects responsible for the sub-bandgap absorption and suppress the detrimental free carrier absorption.The 200-μm-long device presents a propagation loss as low as 2.9 d B/cm.Its responsivity is enhanced from 12.1 m A/W to 112 m A/W at-9 V bias by heating the optical absorption region.With this device,we build an optical power monitoring system that operates in the sampling mode.The minimal detectable optical power of the system is below-22.8 d Bm,while the average power consumption is less than1 m W at a sampling frequency of 10 Hz.Advantages of this scheme in terms of high responsivity,low insertion loss,and low power consumption lend itself to implement the feedback control of advanced large-scale silicon photonic integrated circuits.

Highly efficient enzymolysis and fermentation of corn stalk into L-lactic acid by enzyme-bacteria friendly ionic liquid pretreatment

Ionic liquids(ILs)have been widely used in the pretreatment of biomass.However,the effects of residual ILs on the enzymolysis and fermentation of biomass are still unknown.Therefore,a large quantity of water-washing is usually followed after biomass pretreatment to eliminate the inhibition of residual ILs on subsequent hydrolysis and fermentation steps.In this work,the effect of choline glycine([Ch][Gly])concentration on the activity of cellulase and Bacillus sp.strain P38 was systematically investigated to explore the impacts of residual ILs on enzymolysis and fermentation.The results confirmed that the activities of them were almost not inhibited in low concentrations(less than 0.5 wt%)of[Ch][Gly].Under optimal pretreatment conditions,the maximum cellulose digestibility was 99.23%.Enzymatic hydrolysate was suitable for L-lactic acid fermentation without appreciable inhibition,and the highest sugar-acid conversion rate of 96.33%was obtained by simplified detoxification.This work provides an economic route to produce fermentable sugar and L-lactic acid,which shows an industrial application prospect in lignocellulosic biorefinery.