Stable picosecond soliton transmission is demonstrated numerically by use of concatenated gain-distributed nonlinear amplifying fiber loop mirrors （NALMs）. We show that, as compared with previous soliton transmissio...Stable picosecond soliton transmission is demonstrated numerically by use of concatenated gain-distributed nonlinear amplifying fiber loop mirrors （NALMs）. We show that, as compared with previous soliton transmission schemes that use conventional NALMs or nonlinear optical loop mirror （NOLM） and amplifier combinations, the present scheme permits significant increase of loop-mirror （amplifier） spacing. The broad switching window of the present device and the high quality pulses switched from it provide a reasonable stability range for soliton transmission. Soliton-soliton interactions can be reduced efficiently by using lowly dispersive fibers.展开更多
A new type of optical amplifier based on co-doping erbium in thulium doped fiber is proposed to realize S＋C band gain by dual-wavelength （800＋1410 nm） pumping scheme which is obtainable from laser diode. A novel m...A new type of optical amplifier based on co-doping erbium in thulium doped fiber is proposed to realize S＋C band gain by dual-wavelength （800＋1410 nm） pumping scheme which is obtainable from laser diode. A novel model is established for the co-doped fiber considering the Er^3＋ to Tm^3＋ energy transfer process. Using appropriate fiber parameters and energy transfer parameters, the coupled rate equations are analyzed and solved, the concentrations of Er^3＋ and Tm^3＋ and fiber length were optimized to get more uniform gain. The results predicted that the S＋C band gain can be achieved at the same time by co-doping erbium in thulium doped fluoride fiber.展开更多
A micro-pattern gas detector named leak microstructure （LM） has been studied. A new chemical electrolytic technique is introduced to make perfect shaped LM needles with very sharp tips, and this method may be develo...A micro-pattern gas detector named leak microstructure （LM） has been studied. A new chemical electrolytic technique is introduced to make perfect shaped LM needles with very sharp tips, and this method may be developed to make LM array detectors in batches. The experimental results are presented for both a single needle LM detector and a small LM array detector. The gas gain is up to 105 by calculation from the waveform. Good gain stability and uniformity are achieved. The light emission from the needle tip is also measured in Ar/CF4 （95/5） gas mixture. The result shows a promising application for imaging.展开更多
Band structure, electron distribution, direct-bandgap light emission, and optical gain of tensile strained, n-doped Ge at different temperatures were calculated. We found that the heating effects not only increase the...Band structure, electron distribution, direct-bandgap light emission, and optical gain of tensile strained, n-doped Ge at different temperatures were calculated. We found that the heating effects not only increase the electron occupancy rate in the Γ valley of Ge by thermal excitation, but also reduce the energy difference between its Γ valley and L valley. However,the light emission enhancement of Ge induced by the heating effects is weakened with increasing tensile strain and n-doping concentration. This phenomenon could be explained by that Ge is more similar to a direct bandgap material under tensile strain and n-doping. The heating effects also increase the optical gain of tensile strained, n-doped Ge at low temperature, but decrease it at high temperature. At high temperature, the hole and electron distributions become more flat, which prevent obtaining higher optical gain. Meanwhile, the heating effects also increase the free-carrier absorption. Therefore, to obtain a higher net maximum gain, the tensile strained, n-doped Ge films on Si should balance the gain increased by the heating effects and the optical loss induced by the free-carrier absorption.展开更多
An analytical equation, which directly relates amplified spontaneous emission （ASE） with small signal gain （SSG） of travelling-wave semiconductor optical amplifier （TWA）, was derived. It was shown by theoretical...An analytical equation, which directly relates amplified spontaneous emission （ASE） with small signal gain （SSG） of travelling-wave semiconductor optical amplifier （TWA）, was derived. It was shown by theoretical analysis and experimental results that calibrated ASE spectra of TWA at different injection currents could be good evaluation and extension of SSG near gain peaks when gain peaks are larger than several decibels. The rapid evaluation method of SSG spectra is very simple, effective and especially applicable to batch measurement.展开更多
We solve the single mode coupled rate equations by computer,simulate the behavior of a gain switch of an AlGaInP red light semiconductor laser diode,and find the characteristic of FWHM of pulses changing with the ampl...We solve the single mode coupled rate equations by computer,simulate the behavior of a gain switch of an AlGaInP red light semiconductor laser diode,and find the characteristic of FWHM of pulses changing with the amplitude of modulation signal, the bias current, and the modulated frequency. On this basis, we conduct experiments. The experiment results accord with the simulations well.展开更多
基金This work was supported by the National NaturalScience Foundation of China (No. 60277016) and theGuangdong Natural Science Foundation of China (No.021357 and 04011761).
文摘Stable picosecond soliton transmission is demonstrated numerically by use of concatenated gain-distributed nonlinear amplifying fiber loop mirrors （NALMs）. We show that, as compared with previous soliton transmission schemes that use conventional NALMs or nonlinear optical loop mirror （NOLM） and amplifier combinations, the present scheme permits significant increase of loop-mirror （amplifier） spacing. The broad switching window of the present device and the high quality pulses switched from it provide a reasonable stability range for soliton transmission. Soliton-soliton interactions can be reduced efficiently by using lowly dispersive fibers.
基金This work was supported by the China Scholarship Council, the Natural Science Foundation of Shandong Province of China (No. Y2003G01, Y2002G06)the Research Found for the Doctoral Program of High Ed-ucation of China (No. 20020422048).
文摘A new type of optical amplifier based on co-doping erbium in thulium doped fiber is proposed to realize S＋C band gain by dual-wavelength （800＋1410 nm） pumping scheme which is obtainable from laser diode. A novel model is established for the co-doped fiber considering the Er^3＋ to Tm^3＋ energy transfer process. Using appropriate fiber parameters and energy transfer parameters, the coupled rate equations are analyzed and solved, the concentrations of Er^3＋ and Tm^3＋ and fiber length were optimized to get more uniform gain. The results predicted that the S＋C band gain can be achieved at the same time by co-doping erbium in thulium doped fluoride fiber.
基金Supported by National Natural Science Foundation of China (10775151)Youth Fund of Institute of High Energy Physics, Chinese Academy of Sciences, Foundation of the State Key Laboratory of Particle Detection and Electronics of IHEP
文摘A micro-pattern gas detector named leak microstructure （LM） has been studied. A new chemical electrolytic technique is introduced to make perfect shaped LM needles with very sharp tips, and this method may be developed to make LM array detectors in batches. The experimental results are presented for both a single needle LM detector and a small LM array detector. The gas gain is up to 105 by calculation from the waveform. Good gain stability and uniformity are achieved. The light emission from the needle tip is also measured in Ar/CF4 （95/5） gas mixture. The result shows a promising application for imaging.
基金Project supported by the National Basic Research Development Program of China(Grant No.2013CB632103)the National Natural Science Foundation of China(Grant Nos.61377045,61435013,and 61176013)
文摘Band structure, electron distribution, direct-bandgap light emission, and optical gain of tensile strained, n-doped Ge at different temperatures were calculated. We found that the heating effects not only increase the electron occupancy rate in the Γ valley of Ge by thermal excitation, but also reduce the energy difference between its Γ valley and L valley. However,the light emission enhancement of Ge induced by the heating effects is weakened with increasing tensile strain and n-doping concentration. This phenomenon could be explained by that Ge is more similar to a direct bandgap material under tensile strain and n-doping. The heating effects also increase the optical gain of tensile strained, n-doped Ge at low temperature, but decrease it at high temperature. At high temperature, the hole and electron distributions become more flat, which prevent obtaining higher optical gain. Meanwhile, the heating effects also increase the free-carrier absorption. Therefore, to obtain a higher net maximum gain, the tensile strained, n-doped Ge films on Si should balance the gain increased by the heating effects and the optical loss induced by the free-carrier absorption.
基金This work was supported by the National "973" Projectof China (No. G2000036605), the National "863" Pro-gram of China (No. 2002AA312160), and the Scienceand Technology Foundation of Wuhan City
文摘An analytical equation, which directly relates amplified spontaneous emission （ASE） with small signal gain （SSG） of travelling-wave semiconductor optical amplifier （TWA）, was derived. It was shown by theoretical analysis and experimental results that calibrated ASE spectra of TWA at different injection currents could be good evaluation and extension of SSG near gain peaks when gain peaks are larger than several decibels. The rapid evaluation method of SSG spectra is very simple, effective and especially applicable to batch measurement.
文摘We solve the single mode coupled rate equations by computer,simulate the behavior of a gain switch of an AlGaInP red light semiconductor laser diode,and find the characteristic of FWHM of pulses changing with the amplitude of modulation signal, the bias current, and the modulated frequency. On this basis, we conduct experiments. The experiment results accord with the simulations well.
