Reduction of modulator energy consumption to 10 fJ∕bit is essential for the sustainable development of communication systems.Lumped modulators might be a viable solution if instructed by a complete theory system.Here...Reduction of modulator energy consumption to 10 fJ∕bit is essential for the sustainable development of communication systems.Lumped modulators might be a viable solution if instructed by a complete theory system.Here,we present a complete analytical electro-optic response theory,energy consumption analysis,and eye diagrams on absolute scales for lumped modulators.Consequently the speed limitation is understood and alleviated by single-drive configuration,and comprehensive knowledge into the energy dependence on structural parameters significantly reduces energy consumption.The results show that silicon modulation energy as low as 80.8 and 21.5 fJ∕bit can be achieved at 28 Gbd under 50 and 10 Ω impedance drivers,respectively.A 50 Gbd modulation is also shown to be possible.The analytical models can be extended to lumped modulators on other material platforms and offer a promising solution to the current challenges of modulation energy reduction.展开更多
Optical pulses are fundamentally defined by their temporal and spectral properties.The ability to control pulse properties allows practitioners to efficiently leverage them for advanced metrology,high speed optical co...Optical pulses are fundamentally defined by their temporal and spectral properties.The ability to control pulse properties allows practitioners to efficiently leverage them for advanced metrology,high speed optical communications and attosecond science.Here,we report 11×temporal compression of 5.8 ps pulses to 0.55 ps using a low power of 13.3 W.The result is accompanied by a significant increase in the pulse peak power by 9.4×.These results represent the strongest temporal compression demonstrated to date on a complementary metal–oxide–semiconductor(CMOS)chip.In addition,we report the first demonstration of on-chip spectral compression,3.0×spectral compression of 480 fs pulses,importantly while preserving the pulse energy.The strong compression achieved at low powers harnesses advanced on-chip device design,and the strong nonlinear properties of backend-CMOS compatible ultra-silicon-rich nitride,which possesses absence of two-photon absorption and 500×larger nonlinear parameter than in stoichiometric silicon nitride waveguides.The demonstrated work introduces an important new paradigm for spectro-temporal compression of optical pulses toward turn-key,on-chip integrated systems for all-optical pulse control.展开更多
We report an above-band-gap radiative transition in the photoluminescence spectra of single crystalline Ge in the temperature range of 20-296 K. The temperature-independence of the peak position at -0.74 eV is remarka...We report an above-band-gap radiative transition in the photoluminescence spectra of single crystalline Ge in the temperature range of 20-296 K. The temperature-independence of the peak position at -0.74 eV is remarkably different from the behavior of direct and indirect gap transitions in Ge. This transition is observed in n-type, p-type, and intrinsic single crystal Ge alike, and its intensity decreases with the increase of temperature with a small activation energy of 56 meV. Some aspects of the transition are analogous to III-V semiconductors with dilute nitrogen doping, which suggests that the origin could be related to an isoelectronic defect.展开更多
基金National Natural Science Foundation of China(NSFC)(61120106012)
文摘Reduction of modulator energy consumption to 10 fJ∕bit is essential for the sustainable development of communication systems.Lumped modulators might be a viable solution if instructed by a complete theory system.Here,we present a complete analytical electro-optic response theory,energy consumption analysis,and eye diagrams on absolute scales for lumped modulators.Consequently the speed limitation is understood and alleviated by single-drive configuration,and comprehensive knowledge into the energy dependence on structural parameters significantly reduces energy consumption.The results show that silicon modulation energy as low as 80.8 and 21.5 fJ∕bit can be achieved at 28 Gbd under 50 and 10 Ω impedance drivers,respectively.A 50 Gbd modulation is also shown to be possible.The analytical models can be extended to lumped modulators on other material platforms and offer a promising solution to the current challenges of modulation energy reduction.
基金supported by the National Research Foundation Competitive Research Grant(NRF-CRP18-2017-03)the MOE ACRF Tier 2 Grant.
文摘Optical pulses are fundamentally defined by their temporal and spectral properties.The ability to control pulse properties allows practitioners to efficiently leverage them for advanced metrology,high speed optical communications and attosecond science.Here,we report 11×temporal compression of 5.8 ps pulses to 0.55 ps using a low power of 13.3 W.The result is accompanied by a significant increase in the pulse peak power by 9.4×.These results represent the strongest temporal compression demonstrated to date on a complementary metal–oxide–semiconductor(CMOS)chip.In addition,we report the first demonstration of on-chip spectral compression,3.0×spectral compression of 480 fs pulses,importantly while preserving the pulse energy.The strong compression achieved at low powers harnesses advanced on-chip device design,and the strong nonlinear properties of backend-CMOS compatible ultra-silicon-rich nitride,which possesses absence of two-photon absorption and 500×larger nonlinear parameter than in stoichiometric silicon nitride waveguides.The demonstrated work introduces an important new paradigm for spectro-temporal compression of optical pulses toward turn-key,on-chip integrated systems for all-optical pulse control.
基金supported by the Si-Based Laser Initiative of the Multidisciplinary University Research Initiative (MURI)sponsored by the Air Force Office of Scientific Research (AFOSR), USAsupervised by Dr. Gernot Pomrenke.
文摘We report an above-band-gap radiative transition in the photoluminescence spectra of single crystalline Ge in the temperature range of 20-296 K. The temperature-independence of the peak position at -0.74 eV is remarkably different from the behavior of direct and indirect gap transitions in Ge. This transition is observed in n-type, p-type, and intrinsic single crystal Ge alike, and its intensity decreases with the increase of temperature with a small activation energy of 56 meV. Some aspects of the transition are analogous to III-V semiconductors with dilute nitrogen doping, which suggests that the origin could be related to an isoelectronic defect.
