The high-temperature sensitivity of the silicon material index limits the applications of silicon-based micro-ring resonators in integrated photonics. To realize a low but broadband temperature-dependent-wavelength-sh...The high-temperature sensitivity of the silicon material index limits the applications of silicon-based micro-ring resonators in integrated photonics. To realize a low but broadband temperature-dependent-wavelength-shift microring resonator, designing a broadband athermal waveguide becomes a significant task. In this work,we propose a broadband athermal waveguide that shows a low effective thermo-optical coefficient of1 × 10^(-6)∕K from 1400 to 1700 nm. The proposed waveguide shows a low-loss performance and stable broadband athermal property when it is applied to ring resonators, and the bending loss of ring resonators with a radius of >30 μm is 0.02 dB/cm.展开更多
Octave-spanning frequency comb generation in microresonators is promising, but strong spectral losses caused by material absorption and mode coupling between two polarizations or mode families can be detrimental. We e...Octave-spanning frequency comb generation in microresonators is promising, but strong spectral losses caused by material absorption and mode coupling between two polarizations or mode families can be detrimental. We examine the impact of the spectral loss and propose robust comb generation with a loss of even 300 dB/cm.Cavity nonlinear dynamics show that a phase change associated with spectral losses can facilitate phase matching and Kerr comb generation. Given this unique capability, we propose a novel architecture of on-chip spectroscopy systems.展开更多
Intensive research on instructed second language acquisition(ISLA)over the last two decades has,overall,pointed to the usefulness of Focus on Form—a type of pedagogical intervention that engages learnersmetaling ui...Intensive research on instructed second language acquisition(ISLA)over the last two decades has,overall,pointed to the usefulness of Focus on Form—a type of pedagogical intervention that engages learnersmetaling uistic attention in an otherwise meaning-based environment—in fostering learners communicative accuracy. A finer-grained understandin g thereof has yet to be sought,especially vis-à-vis the type of focus on form and the nature of the target construction as potential mitigating variables.This small-scale study attempts to investig ate the effectiveness of exp licit Focus on Form(FonF)in the acquisition of the English passive construction.Two intact,lower-advanced level English-as-a-second-language(ESL)classes of a community English program in the U.S.partici pated in the study,with one serving as an experimental group and the other a control group.The study adopted apretest,posttest,and delayed posttest design and spanned five weeks,including two weeks of treatment wherein the experimental group received eight mini-sessions of C-R and metaling uistic explanation,while the control group continued with their regular instruction.Results indicated that the treatment significantly facilitated the learning of the passive construction.展开更多
基金National Basic Research Program of China(973)(2014CB340104/3)National Natural Science Foundation of China(NSFC)(61775164,61335005,61377076,61575142,61431009)Tianjin University
文摘The high-temperature sensitivity of the silicon material index limits the applications of silicon-based micro-ring resonators in integrated photonics. To realize a low but broadband temperature-dependent-wavelength-shift microring resonator, designing a broadband athermal waveguide becomes a significant task. In this work,we propose a broadband athermal waveguide that shows a low effective thermo-optical coefficient of1 × 10^(-6)∕K from 1400 to 1700 nm. The proposed waveguide shows a low-loss performance and stable broadband athermal property when it is applied to ring resonators, and the bending loss of ring resonators with a radius of >30 μm is 0.02 dB/cm.
基金National Basic Research Program of China(973)(2014CB340104/3,61775164,61335005,61377076,61575142,61431009)Advanced Integrated Optoelectronics Facility at the Tianjin University
文摘Octave-spanning frequency comb generation in microresonators is promising, but strong spectral losses caused by material absorption and mode coupling between two polarizations or mode families can be detrimental. We examine the impact of the spectral loss and propose robust comb generation with a loss of even 300 dB/cm.Cavity nonlinear dynamics show that a phase change associated with spectral losses can facilitate phase matching and Kerr comb generation. Given this unique capability, we propose a novel architecture of on-chip spectroscopy systems.
文摘Intensive research on instructed second language acquisition(ISLA)over the last two decades has,overall,pointed to the usefulness of Focus on Form—a type of pedagogical intervention that engages learnersmetaling uistic attention in an otherwise meaning-based environment—in fostering learners communicative accuracy. A finer-grained understandin g thereof has yet to be sought,especially vis-à-vis the type of focus on form and the nature of the target construction as potential mitigating variables.This small-scale study attempts to investig ate the effectiveness of exp licit Focus on Form(FonF)in the acquisition of the English passive construction.Two intact,lower-advanced level English-as-a-second-language(ESL)classes of a community English program in the U.S.partici pated in the study,with one serving as an experimental group and the other a control group.The study adopted apretest,posttest,and delayed posttest design and spanned five weeks,including two weeks of treatment wherein the experimental group received eight mini-sessions of C-R and metaling uistic explanation,while the control group continued with their regular instruction.Results indicated that the treatment significantly facilitated the learning of the passive construction.
