载流子导引的折射率变化偏振相关性研究

分析了载流子浓度、张应变量大小、量子阱阱宽和量子阱垒区材料组分对量子阱结构TE模和TM模折射率变化的影响.综合调配以上参数得到1530—1570 nm波长范围内同时具有大的折射率变化量(10^-2量级)和折射率变化低偏振相关(10^-4量级)的量子阱结构.研究表明,不同的调配参数组合可以得到同一波长范围内基本一致的折射率变化谱.     

Calculation of the carrier-induced refractive index change in InSb

We report a theoretical model for an estimate of carrier-induced changes in the refractive index of InSb at room temperature. The dispersion of n within the photon-energy interval of 0.12–0.24 eV is investigated for nonequilibrium carrier concentrations of 10¹⁵–10¹⁸ cm^–3. An analysis of the influence of the initial carrier density on n is performed. The obtained results can help to develop InSb opto-electronic devices.     

InGaAsP/InP evanescent mode waveguide optical isolators and their application to InGaAsP/InP/Si hybrid evanescent optical isolators

We theoretically investigated InGaAsP/InP evanescent mode waveguide optical isolators and proposed their application to InGaAsP/InP/Si hybrid evanescent optical isolators. InGaAsP/InP evanescent optical isolators are composed of semiconductor optical amplifier (SOA) waveguides having InGaAsP multiple quantum well (MQW) active layer and upper InGaAsP waveguide layer with ferromagnetic layer. Optical isolation is obtained for evanescent optical mode in the InGaAsP waveguide layer. InGaAsP/InP/Si hybrid evanescent optical isolators are theoretically proposed based on the idea of InGaAsP/InP evanescent optical isolators. InGaAsP/InP/Si hybrid evanescent optical isolators are composed of ferromagnetic metal loaded silicon evanescent waveguides with wafer-bonded InGaAsP/InP optical gain material. The optical isolation and propagation loss are discussed with the structure of silicon evanescent waveguides, and optical isolation of 8.0 dB/mm was estimated. The concept of semiconductor evanescent mode optical isolators is feasible with InP based photonic integrated circuits and advanced silicon photonics.     

Analysis and optimization of an InGaAsP/InP waveguide variable optical attenuator

An InGaAsP/InP waveguide variable optical attenuator (VOA) is proposed in this paper. The device consists of straight input and output waveguides and an S-bend waveguide. An electrode is deposited on a portion of the waveguide to form an active region so that its refractive index can be modified by a current injection, resulting in the variation of the transmitted optical power. The beam propagation method is employed in the numerical simulation and the device structure is optimized using a genetic algorithm. The optimized VOA has a low excess loss (<1 dB) and a large dynamic range of about 40 dB.     

Integrated MQW intermixed InGaAsP/InP waveguide photodiodes

A multi-wavelength Quantum well (QW) waveguide photodiode (PD) have been designed for Coarse Wavelength Division Multiplexing (CWDM) systems in which spatial tailoring of the bandgap with post growth F implanted QW intermixing of InGaAsP/InP multi QWs for the integration have been considered. Two separate structures with different composition but same well widths are necessary to detect all CWDM wavelengths. For In_0.5995Ga_0.4005As_0.8521P_0.1479 well there is a 12 channel coverage from 1,270 to 1,490 nm and for the In_0.5540Ga_0.4460As_0.9489P_0.0511 well the 14 channel spans from 1,350 to 1,610 nm. A carrier tunneling time of 20 ps along with the transit time limited bandwidth of 86 GHz gives a 3 dB bandwidth of 41 GHz by optimizing the i-MQW thickness and dopant concentration of the different layers of the waveguide. A maximum efficiency of 22% with insertion loss of 0.4–23 dB has been obtained.     

4×8 optoelectronic matrix switch equipment using InGaAsP/InP heterojunction switching photodiodes

A four input-port and an eight output-port optoelectronic matrix switch using InGaAsP/InP hetero-junction switching photodiodes was fabricated and its characteristics studied. The characteristics of the broadband switching equipment, as well as those of individual components, such as the switching photodiodes, InGaAsP/InP semiconductor lasers, eight-port optical dividers and receiver circuits, are discussed from the viewpoint of analogue signal switching. The signal-to-noise ratio attained is more than 40dB for a 30MHz bandwidth television signal. Differential gain and differential phase are less than 2% and 2°, respectively, isolation is higher than 80 dB. Crosstalk between adjacent channels is suppressed below-60 dB over the band between d.c. and 100 MHz by a simple metallic shield at the input and output electric circuits.     

Collective spontaneous emission in a waveguide with a near-zero refractive index

The optimum conditions for observing superradiance and subradiance effects in an ensemble of two-level atoms, placed in a waveguide cladding with a metamaterial with near-zero refractive index, are discussed.     

Acoustoelectronic interaction in InGaAsP/InP laser heterostructures

The dynamics of change in the spectral characteristics of the emission from a laser heterostructure due to an alternating strain induced by a surface acoustic wave is investigated. The spectral distributions of the laser radiation intensities are analyzed with the aim of elucidating the mechanisms responsible for the interactions occurring in the laser heterostructure. A model is proposed for describing the experimental data, and their theoretical analysis is performed. It is demonstrated that the acoustoelectronic interaction is dominant under the action of surface waves. The deviation of the observed frequency modulation of radiation is determined from a comparison of the theoretical calculations with experimental data.     

Minimization of thermal effects in a waveguide structure optical switch

Many studies have been performed on III–V semiconductor all-optical switches with a Fabry–Perot or a waveguide structure. Nonlinear effects have been observed in these devices but fast thermal effects occur which often limit their performances, especially their speed. We report a theoretical study of a waveguide device experimentally studied elsewhere, made of a III–V active material film with a grating coupler and epitaxied on a Bragg reflector.     

Acousto-electron interaction in InGaAsP/InP laser heterostructures

The frequency modulation of the heterolaser radiation under the ultrasonic strain has been found out. The dynamic and static analysis of the spectral parameters change caused by the alternating strain has been fulfilled. A model is proposed for describing the experimental data, and their theoretical analysis is performed. It is demonstrated that the acousto-electron interaction is dominant under the action of surface waves in InGaAsP/InP laser heterostructures.     

Directional control of optical power in integrated InP/InGaAsP extended cavity mode-locked ring lasers

We report on a passively mode-locked InP/InGaAsP multiple quantum well semiconductor ring laser that operates at a 20 GHz repetition rate and around 1575 nm wavelength. The device has been realized using the active-passive integration technology in a standardized photonic integration platform. We demonstrate experimentally for the first time to our knowledge that the relative positioning of the amplifier and absorber in a monolithically integrated ring laser can be used to control the balance of power between counterpropagating fields in the mode-locked state. The directional power balance is verified to be in agreement with a model previously reported.     

Spatiotemporal collapse in a nonlinear waveguide with a randomly fluctuating refractive index

Analytical results, based on the virial theorem and the Furutsu-Novikov theorem, of the spatiotemporal evolution of a pulse in a nonlinear waveguide with a randomly fluctuating refractive index are presented. For initial conditions in which total collapse occurs in a homogeneous waveguide, random fluctuations postpone the collapse. Sufficiently large-amplitude and short-wavelength fluctuations can cause an initially localized pulse to spread instead of contracting. We show that the disorder can be applied to induce a high degree of controllability of the spatiotemporal extent of the pulses in the nonlinear waveguide.     

Nonadiabatic Landau-Zener tunneling in waveguide arrays with a step in the refractive index

Landau-Zener tunneling is discussed in connection with optical waveguide arrays. Light injected in a specific band of the Bloch spectrum in the propagation constant can be transmitted to another band, changing its physical properties. This can be achieved using two coupled waveguide arrays with different refractive indices. The step in the refractive index causes wave "acceleration" and thus induces strongly nonadiabatic Landau-Zener tunneling. Theoretically, the analysis is performed by considering a Schr?dinger equation in a periodic potential with a step. The region of physical parameters where this phenomenon can occur is analytically determined and a realistic experimental setup is suggested. Its application could allow the realization of light filters.     

利用泄漏波导测量低折射率薄膜的折射率和厚度

根据泄漏波导原理对K_9玻璃基板上的冰晶石薄膜进行折射率测量,达到的精度为1×10~(-4),与真实波导的情况相似。文中讨论了利用添加高折射率薄层减小待测薄膜的最小厚度的可能性。文中还利用光电方法观察反射光中暗条纹的方法判别波导的激发,并测出了冰晶石薄膜在4500到6500范围内的折射率。     

场助InP／InGaAsP／InP半导体光电阴极异质结能带的计算

采用双曲型的渐变函数,同时考虑加偏压时引起的阴极表面空间电荷区的变化,对场助InP/TnGaAsP/InP半导体光电阴极异质结的能带结构进行了详细的分析和计算,得到了在不同材料参数时,异质结能带结构的分布曲线.计算结果指出了达到理想的异质结传输效率时,发射层的厚度和掺杂浓度、吸收层的掺杂浓度、异质结界面处渐变区宽度以及场助偏压应满足的条件.它有助于场助半导体光电阴极的结构设计和材料参数的选择.     

Modulation instability of pulsed radiation in an optical waveguide in the presence of the traveling refractive index wave

The conditions for the onset of modulation instability of wave packets in an optical waveguide in the presence of the traveling refractive index wave are investigated. An expression governing the growth rate of a small harmonic perturbation at the early development stage of the modulation instability is obtained. Based on numerical analysis, the behavior of the wave packet at the developed modulation instability stage is studied for different parameters of the waveguide and the refractive index wave.     

Multilayer graphene refractive index tuning by optical power

Graphene's optical absorption coefficient increases linearly with the number of layers making it more effective in the construction of optical tuning graphene-based devices. Refractive index(RI) is one of the important optical parameters of the graphene for accurately describing its optical characteristics and further applications. In view of the RI research of the multilayer graphene is lacking and existing measurement methods are complicated. Optical power tuning RI of multilayer graphene is investigated using a simple measurement and no temperature cross sensitivity all optical fiber sensing structure.Optical power tuning RI characteristics of multilayer graphene are studied by tuning the introducing broad band light power from 0.57 mW to 22.7 m W. Different thickness graphene coating shows different tuning efficiency. At 4.86-μm thickness,a 3.433-nm Bragg wavelength shift is obtained with 156.2-pm/mW wavelength versus optical power tuning sensitivity corresponding to 3.25×10~3 RI change and 0.154 URI/W(URI, unit of RI) RI optical power tuning efficiency.     

Opto-electronic integrated circuits using the InGaAsP/InP system

Recent developments in opto-electronic integrated circuits (OEICs) using the InGaAsP/InP system which is monolithically integrated with opto-electronic and electronic devices are discussed. The technological problems for the development of the OEICs are explained by reviewing recent developments in OEICs.     

变波长逆WKB方法确定单模渐变平面光波导的折射率轮廓

将渐变波导模式方程(WKB积分方程)化为分段积分,以波导某一模式在不同波长下的转折点为分段点,当波长相差很小时,相应的转折点相差也很小,可在各个分段积分中作折线近似,从而从理论上推出确定波导轮廓数据的递推式.以所得轮廓必须满足光滑条件为判据,最后定出波导的轮廓.该方法尤其适用于单模渐变波导,而且无需事先假设待定轮廓的函数形式.本文对双曲止割和抛物线轮廓的理想波导进行了计算机模拟,结果证明该方法的精度达到10~(-3)甚至于更高.而且理论上具有分割愈密,精度愈高的优点.