11 research outputs found
On-chip Q-factor greater than 1 billion
A record Q-factor of 1.1 billion is demonstrated in on-chip silica whispering-gallery resonators. Using the devices, sub-milliwatt parametric oscillation threshold is measured in 9 GHz free-spectral-range devices
On-chip Q-factor greater than 1 billion
A record Q-factor of 1.1 billion is demonstrated in on-chip silica whispering-gallery resonators. Using the devices, sub-milliwatt parametric oscillation threshold is measured in 9 GHz free-spectral-range devices
Impact of spatio-temporal thermal decoherence on soliton microcombs in multimode microresonators
The phase noise of the soliton repetition rate is experimentally characterized in silica microresonators. In conjunction with dispersive wave quieting of pump technical noise, spatio-temporal fluctuations of distinct transverse modes set a limit to performance
Impact of spatio-temporal thermal decoherence on soliton microcombs in multimode microresonators
The phase noise of the soliton repetition rate is experimentally characterized in silica microresonators. In conjunction with dispersive wave quieting of pump technical noise, spatio-temporal fluctuations of distinct transverse modes set a limit to performance
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Nitrogen availability prevents oxidative effects of salinity on wheat growth and photosynthesis by up-regulating the antioxidants and osmolytes metabolism, and secondary metabolite accumulation.
Funder: NorthWest A&F University Yaangling, Shaanxi, China.BACKGROUND: Salinity is one of the damaging abiotic stress factor. Proper management techniques have been proposed to considerably lower the intensity of salinity on crop growth and productivity. Therefore experiments were conducted to assess the role of improved nitrogen (N) supplementation on the growth and salinity stress tolerance in wheat by analyzing the antioxidants, osmolytes and secondary metabolites. RESULTS: Salinity (100 mM NaCl) stress imparted deleterious effects on the chlorophyll and carotenoid synthesis as well as the photosynthetic efficiency. N supplementation resulted in increased photosynthetic rate, stomatal conductance and internal CO2 concentration with effects being much obvious in seedlings treated with higher N dose. Under non-saline conditions at both N levels, protease and lipoxygenase activity reduced significantly reflecting in reduced oxidative damage. Such effects were accompanied by reduced generation of toxic radicals like hydrogen peroxide and superoxide, and lipid peroxidation in N supplemented seedlings. Antioxidant defence system was up-regulated under saline and non-saline growth conditions due to N supplementation leading to protection of major cellular processes like photosynthesis, membrane structure and function, and mineral assimilation. Increased osmolyte and secondary metabolite accumulation, and redox components in N supplemented plants regulated the ROS metabolism and NaCl tolerance by further strengthening the antioxidant mechanisms. CONCLUSIONS: Findings of present study suggest that N availability regulated the salinity tolerance by reducing Na uptake and strengthening the key tolerance mechanisms
Hertz-linewidth semiconductor lasers using CMOS-ready ultra-high- microresonators
Driven by narrow-linewidth bench-top lasers, coherent optical systems
spanning optical communications, metrology and sensing provide unrivalled
performance. To transfer these capabilities from the laboratory to the real
world, a key missing ingredient is a mass-produced integrated laser with
superior coherence. Here, we bridge conventional semiconductor lasers and
coherent optical systems using CMOS-foundry-fabricated microresonators with
record high factor over 260 million and finesse over 42,000. Five
orders-of-magnitude noise reduction in the pump laser is demonstrated, and for
the first time, fundamental noise below 1 Hz Hz is achieved in an
electrically-pumped integrated laser. Moreover, the same configuration is shown
to relieve dispersion requirements for microcomb generation that have
handicapped certain nonlinear platforms. The simultaneous realization of
record-high factor, highly coherent lasers and frequency combs using
foundry-based technologies paves the way for volume manufacturing of a wide
range of coherent optical systems.Comment: 19 pages, 11 figure
Probing material absorption and optical nonlinearity of integrated photonic materials
Optical microresonators with high quality () factors are essential to a
wide range of integrated photonic devices. Steady efforts have been directed
towards increasing microresonator factors across a variety of platforms.
With success in reducing microfabrication process-related optical loss as a
limitation of , the ultimate attainable , as determined solely by the
constituent microresonator material absorption, has come into focus. Here, we
report measurements of the material-limited factors in several photonic
material platforms. High- microresonators are fabricated from thin films of
SiO, SiN, AlGaAs and TaO. By using
cavity-enhanced photothermal spectroscopy, the material-limited is
determined. The method simultaneously measures the Kerr nonlinearity in each
material and reveals how material nonlinearity and ultimate vary in a
complementary fashion across photonic materials. Besides guiding microresonator
design and material development in four material platforms, the results help
establish performance limits in future photonic integrated systems.Comment: Maodong Gao, Qi-Fan Yang and Qing-Xin Ji contributed equally to this
work. 9 pages, 4 figures, 1 tabl
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Probing material absorption and optical nonlinearity of integrated photonic materials.
Optical microresonators with high quality (Q) factors are essential to a wide range of integrated photonic devices. Steady efforts have been directed towards increasing microresonator Q factors across a variety of platforms. With success in reducing microfabrication process-related optical loss as a limitation of Q, the ultimate attainable Q, as determined solely by the constituent microresonator material absorption, has come into focus. Here, we report measurements of the material-limited Q factors in several photonic material platforms. High-Q microresonators are fabricated from thin films of SiO2, Si3N4, Al0.2Ga0.8As, and Ta2O5. By using cavity-enhanced photothermal spectroscopy, the material-limited Q is determined. The method simultaneously measures the Kerr nonlinearity in each material and reveals how material nonlinearity and ultimate Q vary in a complementary fashion across photonic materials. Besides guiding microresonator design and material development in four material platforms, the results help establish performance limits in future photonic integrated systems