高吸收ZnSe多晶无镜光学双稳的实验观测

本文对具高吸收的ZnSe多晶材料的增加吸收型光学双稳性进行了实验观测,发现在介质的吸收远高于过去提出的理论判据时,仍能获得双稳输出,并测定了阈值开关功率与光斑尺寸及样品厚度的关系.采用分层模型分析实验结果,定性地解释了实验现象.     

The dynamics of direction-dependent switching in nonlinear chirped gratings

Nonlinear chirped gratings are numerically demonstrated to have a direction-dependent switching behavior. For the two incident directions, bistability exists with different switching-on powers, and the instable high transmissivity states have different critical powers. The direction-dependent bistability is due to the difference of the energy contained in the gratings for the two incident directions; the direction-dependent critical powers for instability origin from the different modulation instability threshold. Furthermore, it is first reported that for instable output there are spectral side lobes whose frequency shifts relative to carrier frequency have jumps at some input powers.     

Controllable optical bistability and multistability in asymmetric double quantum wells via spontaneously generated coherence

We investigate the nonlinear optical phenomena of the optical bistability and multistability via spontaneously generated coherence in an asymmetric double quantum well structure coupled by a weak probe field and a controlling field. It is shown that the threshold and hysteresis cycle of the optical bistability can be conveniently controlled only by adjusting the intensity of the SGC or the controlling field. Moreover, switching between optical bistability and multistability can be achieved. These studies may have practical significance for the preparation of optical bistable switching device.     

Scaling properties of switching pulses

We investigate analytically the switching process of a bistable system which is described near each limit point by a single ordinary nonlinear differential equation. For a holding beam near the limit point and a rectangular switching pulse, we prove that the requirement of switching imposes a constraint on the pulse area. This results hold for bistability in general and is applied to purely dispersive optical bistability.     

ZnSe－ZnTe多量子阱室温下的反射型皮秒激子光双稳

本文首次研究了ＺｎＳｅ－ＺｎＴｅ多量子阱在室温下的反射型皮秒激子光双稳，实验结果表明，ＺｎＳｅ－ＺｎＴｅ多量子阱在室温下的反射型皮秒光双稳的阈值光强和对比度分别为１．１ＭＷ／ｃｍ２和６：１．根据测量得到的ＺｎＳｅ－ＺｎＴｅ多量子阱在室温下的激子吸收光谱及激子的非线性吸收理论，归结ＺｎＳｅ－ＺｎＴｅ多量子阱室温下的皮秒光双稳的主要非线性机理为ＺｎＳｅ－ＺｎＴｅ多量子阱的激子饱和吸收引起的折射率变化．     

ZnSe-ZnTe多量子阱室温下的反射型皮秒激子光双稳

本文首次研究了ZnSe-ZnTe多量子阱在室温下的反射型皮秒激子光双稳,实验结果表明,ZnSe-ZnTe多量子阱在室温下的反射型皮秒光双稳的阈值光强和对比度分别为1.1MW/cm²和6:1.根据测量得到的ZnSe-ZnTe多量子阱在室温下的激子吸收光谱及激子的非线性吸收理论,归结ZnSe-ZnTe多量子阱室温下的皮秒光双稳的主要非线性机理为ZnSe-ZnTe多量子阱的激子饱和吸收引起的折射率变化.     

光反馈电激励半导体光学双稳态的开关时间研究

本文使用电子和光子密度的非线性速率方程及近似处理方法,首次讨论了光反馈电激励半导体光学双稳态的开关时间同系统可调参数之间的关系,从实验上研究了该系统的开关时间特性,提出了改善双稳开关时间的方法。     

Long-term stable thermally induced absorptive optical bistability in MBE-grown ZnSe epilayers

MBE-grown ZnSe epilayers released from their GaAs substrates exhibit thermally induced absorptive optical bistability of high contrast ratios and low switching powers in a wide temperature range up to room temperature. For increasing sample thickness or for enhanced reflection realized by inserting the samples into a resonator, counteracting dispersive switching becomes visible. The interplay of both the absorptive and dispersive effects is studied for different samples and varied experimental parameters. Long-term stability of the samples with regard to all switching effects makes them promising candidates for application studies.     

掺Tm激光晶体的可见与红外发光转换及双稳多色开关

理论研究了648nm激光抽运掺Tm晶体的可见与红外发光转换和发光双稳特性.根据系统的耦合速率方程理论,推导了发光转换阈值的解析表达式,数值研究了Tm³⁺能级布居数,辐射光谱以及发光强度等随抽运光强的变化.数值结果表明,648nm激光抽运下可以实现452/469nm蓝光与1716 nm红外光谱的发光转换.在光子雪崩阈值附近,可以观察到掺Tm晶体的辐射光谱双稳,荧光色度双稳和发光强度双稳等现象.利用掺Tm晶体的可见与红外发光转换与双稳特性,可以实现抽运功率控制的全固态发光转换器和双稳波长 关键词： 光学双稳 多色开关 掺Tm晶体 光子雪崩     

Optical bistability on a silicon chip

We demonstrate, for the first time to our knowledge, optical bistability on a highly integrated silicon device, using a 5-microm-radius ring resonator. The strong light-confinement nature of the resonator induces nonlinear optical response with low pump power. We show that the optical bistability allows all-optical functionalities, such as switching and memory with microsecond time response and a modulation depth of 10 dB, driven by pump power as low as 45 microW. Silicon optical bistability relies on a fast thermal nonlinear optical effect presenting a 500-kHz modulation bandwidth.     

Surface plasmon-assisted optical switching/bistability at telecommunication wavelengths in nonlinear dielectric gratings

In this paper, we numerically investigate nonlinear optical responses in dielectric gratings coated by flat metallic surface, where the structural parameters are chosen for wavelengths of operation at the telecom regime. The presented designs show the output light reflection with respect to the incident intensity of increasing, decreasing, and non-monotonic belt-shape functions. Nonlinear optical responses including switching and bistability appeared in the telecom region owing to assistance of surface plasmon resonance excited at the metal/dielectric interface, which enhances the diffraction efficiency and induces the momentum matching for the leaky modes of the dielectric grating. This results in electric intensity-effective refractive index dependence enhancement in the Kerr nonlinear media. Our design and investigation of the linear and nonlinear optical responses will provide a general guideline for a hybrid metallic-dielectric structure-based optical switching/bistability device design.     

Optical bistability due to biexcitons in CuCl

Biexciton optical bistability is observed for the first time using CuCl as a nonlinear medium in a Fabry-Perot. The effect is obtained with a high intensity pulsed dye laser which excites the sample and modifies its refractive index near half the biexciton energy. The switching times of the device are shown to be inferior to 500 ps. The bistability is observed at pumped liquid helium and at liquid nitrogen temperatures.     

Transverse effects in absorptive optical bistability

Absorptive bistability loops are computed for a laser beam with a gaussian input spatial profile incident on a unidirectional ring cavity containing a saturable nonlinear medium. Sharp radially dependent switching with wide bistable loops is predicted for large Fresnel numbers. Intermediate Fresnel numbers result in whole beam switching with significant narrowing of the associated bistable loops. At low Fresnel numbers, bistability can disappear. Radially integrated hysteresis loops differ quantitatively from plane-wave predictions.     

CdSxSe1-x玻璃的光双稳皮秒动力学特性研究

本文在掺CdS_xSe_1-x微晶阵列玻璃中观测到上升和下降时间为20微微秒的光学双稳跳跃过程,并从实验数据估算出CdS_xSe_1-x玻璃的三阶非线性系数为1×10^-8esu,与已报道用简并四波混频实验所测得的三阶非线性系数在数量级上一致,快速的光学双稳开关过程以及大的三阶非线性系数显示这种材料的光学双稳态是属于带填充效应的结果。     

含负折射率介质非线性Bragg腔的双稳态特性

研究了含负折射率介质一维光子晶体非线性Bragg腔的透射特性、光学增强和双稳态特性.对负折射率介质无色散和有色散非线性Bragg腔及由两种正折射率介质构成的非线性Bragg腔的透射谱、光学增强、缺陷模的线宽、入射光的红移量、双稳态开关阈值进行了比较.含负折射率介质的非线性Bragg腔可显著增大腔内光学增强效应,降低缺陷模的线宽、入射光的红移量和双稳态开关阈值.     

Recent advances in optical bistability

In this paper, recent advances in optical bistability and gating of semiconductors will be reviewed. Nonlinear mechanisms responsible for switching will be described. The advantages of nonlinear etalons for massive parallelism and current problems in performing such operations will be mentioned.     

Polarization bistability in a nonlinear birefringent Fabry-Perot cavity

Polarization bistability and switching are described theoretically and demonstrated experimentally for a birefringent nonlinear Fabry-Perot cavity.     

非线性一维光子晶体光开关与光双稳

设计和制备了ZnS/ZnSe叠层共 2 0个周期的非线性一维光子晶体光开关与光双稳器件 理论模拟了波长 5 14 .5nm的氩离子激光 ,在阈值功率密度 1.0× 10 5W/cm2 下 ,完全移出光子禁带 ,实现了光开关 同一器件也可作为光学双稳器件 ,实验测出其阈值功率密度为 1.38× 10 5W/cm2 ,双稳开关时间为 10 0ps 理论与实验结果基本一致     

Thermally induced optical bistability in PbTe at room temperature

Thermally induced optical bistability by continuous-wave CO₂ laser excitation is obtained for the first time in PbTe. Optical switching of the etalon atT=300K is achieved for input powers of tens of milliwatts. A theoretical analysis of the input-output characteristics is presented, where the temperature dependence of the free carrier absorption has been accounted for.     

All-optical set-reset flip-flop based on the passive microring-resonator bistability

In this paper, we propose a design for an all-optical R-S flip-flop with separate set and reset inputs, which is based on the optical bistability due to Kerr and two-photon absorption (TPA) effects in the microring resonators. Based on the steady state analysis of the light propagation in nonlinear microrings, variations of hysteresis parameters versus the system variables, such as transmission coefficient, nonlinear refractive index and detuning angle, are analyzed. The switching temporal behavior of the proposed flip-flop is obtained by the microring transient analysis. It is shown that the contrast ratio parameter and the switching power of the proposed all-optical flip-flop can be controlled by system parameters.