In the framework of effective mass approximation, we theoretically investigate the electronic structure of the Si δ-doped InAIN/GaN single quantum well by solving numerically the coupled equations Schrodinger-Poisson...In the framework of effective mass approximation, we theoretically investigate the electronic structure of the Si δ-doped InAIN/GaN single quantum well by solving numerically the coupled equations Schrodinger-Poisson self-consistently. The linear, nonlinear optical absorption coefficients and relative refractive index changes are calculated as functions of the doping concentration and its thickness. The obtained results show that the position and the amplitude of the linear and total optical absorption coefficients and the refractive index changes can be modified by varying the doping concentration and its thickness. In addition, it is found that the maximum of the optical absorption can be red-shifted or blue-shifted by varying the doping concentration. The obtained results are important for the design of various electronic components such as high-power FETs and infrared photonic devices.展开更多
The refractive index change and color centers formation in LiYF4 crystal at room temperature are induced by a femtosecond laser irradiation. A mechanism for refractive index change and color centers formation is propo...The refractive index change and color centers formation in LiYF4 crystal at room temperature are induced by a femtosecond laser irradiation. A mechanism for refractive index change and color centers formation is proposed.展开更多
A novel coupled quantum well structure - quasi-symmetric coupled quantum well （QSCQW） is proposed. In the case of low applied electric field （F = 25 kV/cm） and low absorption loss （a ≈ 100 cm^-1）, a large field...A novel coupled quantum well structure - quasi-symmetric coupled quantum well （QSCQW） is proposed. In the case of low applied electric field （F = 25 kV/cm） and low absorption loss （a ≈ 100 cm^-1）, a large field-induced refractive index change （for TE mode, △n = 0.0106; for TM mode, △n = 0.0115） is obtained in QSCQW structure at operating wavelength λ = 1550 nm. The value is larger by over one to two order of magnitude compared to that in a rectangular quantum well （RQW） and about 50% larger than that of five-step asymmetric coupled quantum well （FACQW） structure under the above work conditions.展开更多
Integrated optics have been stuck in two-dimensional(2D)topologies for decades until the femtosecond laser direct writing(FLDW)technique enables direct lithography of three-dimensional(3D)geometries and nanoscale stru...Integrated optics have been stuck in two-dimensional(2D)topologies for decades until the femtosecond laser direct writing(FLDW)technique enables direct lithography of three-dimensional(3D)geometries and nanoscale structures with rapid prototyping and large-scale manufacturing capabilities in a variety of transparent substrates.The 3D capability of FLDW makes diverse lightwave remapping geometries possible,thereby realizing efficient interconnection of optical systems at different spatial scales,offering a 3D integrated-optics footprint capable of scaling a benchtop optical system down to a 3D glass chip.This work summarizes the history and important milestones in developing FLDW waveguides.Basically,all revolutionary improvements in waveguide key performance,including low propagation loss and small bending radius,were accompanied by the discovery and development of new mechanisms for laser-induced refractive index modification.At the same time,advanced laser beam-shaping methods for tightly focused spatiotemporal fields have been technically grafted onto the fine control of laser–matter interaction in FLDW,notably achieving variable cross-section,arbitrary refractive index and mode-field distribution,thus providing new degrees of freedom beyond the limitations of traditional 2D planar waveguides for more complex photonics circuit design.In this work,we present a comprehensive review of the field,encompassing fundamental mechanisms(such as refractive index modification)as well as key technological advances that enable true 3D integration.On the basis of this,we summarize the basic integrated waveguide components fabricated by FLDW and point out the prospective challenges and future research directions.Tentative routes towards large-area,ultra-broadband,hybrid,multifunctional,all-optical system integration in 3D glass chips are also suggested.展开更多
Based on the effective mass approximation, the Schrodinger equation and Poisson equation in GaAs/AlGaAs multi-quantum wells(MQWs) are self-consistently solved to obtain the wave functions and energy levels of electron...Based on the effective mass approximation, the Schrodinger equation and Poisson equation in GaAs/AlGaAs multi-quantum wells(MQWs) are self-consistently solved to obtain the wave functions and energy levels of electrons in the conduction band for the ground first excited state by considering a lateral electric field(LEF). Then, the effects of size, ternary mixed crystal, doping concentration, and temperature on linear and nonlinear intersubband optical absorption coefficients(IOACs), and refractive index changes(RICs) due to the transition between ground states and the first excited states of electrons are discussed based on Fermi’s golden rule. The results show that, under a fixed LEF, with increase of A1 composition and doping concentration, the IOACs produce a red shift. With increases of both widths of the wells and barriers IOACs appear as blue shifts and their amplitudes increase, but the barrier width change is much more important to affect nonlinear IOACs, whereas increasing the temperature results in a blue shift first and then a red shift of IOACs. When the other parameters are fixed but there is an increase in the LEF, IOACs occur with a blue shift, and the RICs have similar properties.展开更多
基金Supported by the Deanship of Scientific Research of University of Dammam under Grant No 2015134
文摘In the framework of effective mass approximation, we theoretically investigate the electronic structure of the Si δ-doped InAIN/GaN single quantum well by solving numerically the coupled equations Schrodinger-Poisson self-consistently. The linear, nonlinear optical absorption coefficients and relative refractive index changes are calculated as functions of the doping concentration and its thickness. The obtained results show that the position and the amplitude of the linear and total optical absorption coefficients and the refractive index changes can be modified by varying the doping concentration and its thickness. In addition, it is found that the maximum of the optical absorption can be red-shifted or blue-shifted by varying the doping concentration. The obtained results are important for the design of various electronic components such as high-power FETs and infrared photonic devices.
文摘The refractive index change and color centers formation in LiYF4 crystal at room temperature are induced by a femtosecond laser irradiation. A mechanism for refractive index change and color centers formation is proposed.
基金This work was supported by the National NaturalScience Foundation of China under Grant No. 60277034,60436020.
文摘A novel coupled quantum well structure - quasi-symmetric coupled quantum well （QSCQW） is proposed. In the case of low applied electric field （F = 25 kV/cm） and low absorption loss （a ≈ 100 cm^-1）, a large field-induced refractive index change （for TE mode, △n = 0.0106; for TM mode, △n = 0.0115） is obtained in QSCQW structure at operating wavelength λ = 1550 nm. The value is larger by over one to two order of magnitude compared to that in a rectangular quantum well （RQW） and about 50% larger than that of five-step asymmetric coupled quantum well （FACQW） structure under the above work conditions.
基金National Natural Science Foundation of China(Nos.52432001,12404367)Natural Science Foundation of Zhejiang Province(No.LDG25F050001)+1 种基金National Key Research and Development Program of China(No.2024YFB4607403)the“Pioneer”and“Leading Goose”R&D Program of Zhejiang(No.2023C03089).
文摘Integrated optics have been stuck in two-dimensional(2D)topologies for decades until the femtosecond laser direct writing(FLDW)technique enables direct lithography of three-dimensional(3D)geometries and nanoscale structures with rapid prototyping and large-scale manufacturing capabilities in a variety of transparent substrates.The 3D capability of FLDW makes diverse lightwave remapping geometries possible,thereby realizing efficient interconnection of optical systems at different spatial scales,offering a 3D integrated-optics footprint capable of scaling a benchtop optical system down to a 3D glass chip.This work summarizes the history and important milestones in developing FLDW waveguides.Basically,all revolutionary improvements in waveguide key performance,including low propagation loss and small bending radius,were accompanied by the discovery and development of new mechanisms for laser-induced refractive index modification.At the same time,advanced laser beam-shaping methods for tightly focused spatiotemporal fields have been technically grafted onto the fine control of laser–matter interaction in FLDW,notably achieving variable cross-section,arbitrary refractive index and mode-field distribution,thus providing new degrees of freedom beyond the limitations of traditional 2D planar waveguides for more complex photonics circuit design.In this work,we present a comprehensive review of the field,encompassing fundamental mechanisms(such as refractive index modification)as well as key technological advances that enable true 3D integration.On the basis of this,we summarize the basic integrated waveguide components fabricated by FLDW and point out the prospective challenges and future research directions.Tentative routes towards large-area,ultra-broadband,hybrid,multifunctional,all-optical system integration in 3D glass chips are also suggested.
基金Project supported by the National Natural Science Foundation of China(No.61764012)
文摘Based on the effective mass approximation, the Schrodinger equation and Poisson equation in GaAs/AlGaAs multi-quantum wells(MQWs) are self-consistently solved to obtain the wave functions and energy levels of electrons in the conduction band for the ground first excited state by considering a lateral electric field(LEF). Then, the effects of size, ternary mixed crystal, doping concentration, and temperature on linear and nonlinear intersubband optical absorption coefficients(IOACs), and refractive index changes(RICs) due to the transition between ground states and the first excited states of electrons are discussed based on Fermi’s golden rule. The results show that, under a fixed LEF, with increase of A1 composition and doping concentration, the IOACs produce a red shift. With increases of both widths of the wells and barriers IOACs appear as blue shifts and their amplitudes increase, but the barrier width change is much more important to affect nonlinear IOACs, whereas increasing the temperature results in a blue shift first and then a red shift of IOACs. When the other parameters are fixed but there is an increase in the LEF, IOACs occur with a blue shift, and the RICs have similar properties.
