The optical saturation characteristics in the germanium-on-silicon（Ge-on-Si） photodetector are studied for the first time, to the best of our knowledge. The relationship between the optical saturation characteristic...The optical saturation characteristics in the germanium-on-silicon（Ge-on-Si） photodetector are studied for the first time, to the best of our knowledge. The relationship between the optical saturation characteristics and the optical field distribution in the Ge layer is illustrated by the simulation. This theory is verified by comparative experiments with single-injection and dual-injection structures. The dual-injection photodetector with a more balanced and uniform optical field distribution has a 13% higher responsivity at low optical power and 74.4%higher saturation current at 1550 nm. At higher optical power, the bandwidth of the dual-injection photodetector is five times larger than that of the single-injection photodetector.展开更多
We prepared graphene oxide（GO） saturable absorber（SA） successfully through optical deposition method, which is a simple but effective approach to deposit various materials onto substrate under the effects of light...We prepared graphene oxide（GO） saturable absorber（SA） successfully through optical deposition method, which is a simple but effective approach to deposit various materials onto substrate under the effects of light, and investigated several factors that influence the optical deposition result of GO onto optical fiber end, including poly（methyl methacrylate）（PMMA） concentration, light intensity, light mode, and deposition time. The efficient optically deposited GO preserving its nonlinearity guaranteed by GO/PMMA composite formation was also demonstrated. The GO SA prepared by optical deposition shows superior saturable absorption property with modulation depth and nonsaturable loss of 6% and 40%, respectively.展开更多
We demonstrate antimonene as a saturable absorber(SA) to generate an ultrafast mode-locked and Q-switched laser in the 2 μm wavelength region. The two antimonene-based SAs were prepared and inserted separately in a t...We demonstrate antimonene as a saturable absorber(SA) to generate an ultrafast mode-locked and Q-switched laser in the 2 μm wavelength region. The two antimonene-based SAs were prepared and inserted separately in a thulium–holmiumdoped fiber laser to produce the pulsed laser. Antimonene was coated onto a tapered fiber to generate soliton mode-locked pulses and used in thin-film form for the generation of Q-switched pulses. The mode-locking was stable within a pump power of 267 m W–511 m W, and the laser operated at a central wavelength of 1897.4 nm. The mode-locked laser had a pulse width of 1.3 ps and a repetition rate of 12.6 MHz, with a signal-to-noise ratio of 64 d B. Q-switched laser operation was stable at a wavelength of 1890.1 nm within a pump power of 312 m W–381 m W. With the increase in pump power from 312 m W to 381 m W, the repetition rate increased to a maximum of 56.63 k Hz and the pulse width decreased to a minimum value of 2.85 μs. Wide-range tunability of the Q-switched laser was also realized within the wavelength range of1882 nm–1936 nm.展开更多
With the shadowgraph method, three ultrasonic pulses in Water, which correspond to the conversion modes of the fast compressional wave, the transverse wave and the slow compressional wave in the sample of Fluid-Satura...With the shadowgraph method, three ultrasonic pulses in Water, which correspond to the conversion modes of the fast compressional wave, the transverse wave and the slow compressional wave in the sample of Fluid-Saturated Porous Medium (FSPM) respectively,were observed and recorded by CCD camera. The positions of these pulses are cousistent with the computed positions and the time interval between these pulses measured by a transmitterreceiver method.展开更多
文摘The optical saturation characteristics in the germanium-on-silicon（Ge-on-Si） photodetector are studied for the first time, to the best of our knowledge. The relationship between the optical saturation characteristics and the optical field distribution in the Ge layer is illustrated by the simulation. This theory is verified by comparative experiments with single-injection and dual-injection structures. The dual-injection photodetector with a more balanced and uniform optical field distribution has a 13% higher responsivity at low optical power and 74.4%higher saturation current at 1550 nm. At higher optical power, the bandwidth of the dual-injection photodetector is five times larger than that of the single-injection photodetector.
基金Funded by the National Natural Science Foundation of China(Nos.61575150 and 61377092)the Fundamental Research Funds for the Central Universities(WUT:2017II46GX)
文摘We prepared graphene oxide（GO） saturable absorber（SA） successfully through optical deposition method, which is a simple but effective approach to deposit various materials onto substrate under the effects of light, and investigated several factors that influence the optical deposition result of GO onto optical fiber end, including poly（methyl methacrylate）（PMMA） concentration, light intensity, light mode, and deposition time. The efficient optically deposited GO preserving its nonlinearity guaranteed by GO/PMMA composite formation was also demonstrated. The GO SA prepared by optical deposition shows superior saturable absorption property with modulation depth and nonsaturable loss of 6% and 40%, respectively.
基金support for this work through Grant, HiCoE (PRC-2022)the Universiti Malaya for the funding of this work through Grant Nos. RU005-2021 and MGO23-2022。
文摘We demonstrate antimonene as a saturable absorber(SA) to generate an ultrafast mode-locked and Q-switched laser in the 2 μm wavelength region. The two antimonene-based SAs were prepared and inserted separately in a thulium–holmiumdoped fiber laser to produce the pulsed laser. Antimonene was coated onto a tapered fiber to generate soliton mode-locked pulses and used in thin-film form for the generation of Q-switched pulses. The mode-locking was stable within a pump power of 267 m W–511 m W, and the laser operated at a central wavelength of 1897.4 nm. The mode-locked laser had a pulse width of 1.3 ps and a repetition rate of 12.6 MHz, with a signal-to-noise ratio of 64 d B. Q-switched laser operation was stable at a wavelength of 1890.1 nm within a pump power of 312 m W–381 m W. With the increase in pump power from 312 m W to 381 m W, the repetition rate increased to a maximum of 56.63 k Hz and the pulse width decreased to a minimum value of 2.85 μs. Wide-range tunability of the Q-switched laser was also realized within the wavelength range of1882 nm–1936 nm.
文摘With the shadowgraph method, three ultrasonic pulses in Water, which correspond to the conversion modes of the fast compressional wave, the transverse wave and the slow compressional wave in the sample of Fluid-Saturated Porous Medium (FSPM) respectively,were observed and recorded by CCD camera. The positions of these pulses are cousistent with the computed positions and the time interval between these pulses measured by a transmitterreceiver method.
