Transmitted Optical Power through a Tapered Single-Mode Fiber under Dynamic Bending Effects

This paper describes theoretically one of the physical phenomena that take place in a tapered single-mode optical fiber (taper): the transfer of optical power between different order modes. This optical power transfer depends on several factors; one of them is the static bending of the taper, as other authors have reported. In addition to these studies, we have noticed that if the bend angle oscillates, then the magnitude of the optical power transfer is also modified by other additional factors. Thus, at dynamic conditions the transmitted optical power through the taper is also affected by the oscillation frequency. Here we propose a more generic equation system to obtain the coupling coefficient between modes under static as well as dynamic bending conditions. When the presented equations are particularized for static conditions, a complete agreement with other studies is observed. In addition, validating the theoretical justification, some experimental results are also shown.     

Polarization insensitive linear intensity modulation in a Sagnac fiber-optic loop with an electro-optic cell and optoelectronic feedback

We present a modulation scheme consisting of a fiber-optic Sagnac interferometer, which has an electro-optic modulator (Pockels cell) in the loop of the interferometer. In order to diminish the nonlinearity of the Sagnac interferometer transmittance function, we monitor a very small part of the output light intensity by means of a photodiode and then amplify this signal by a constant factor ξ. This amplified signal is added to the electrical modulating signal that is being applied to the electro-optical modulator. The consequence of introducing this feedback loop is that by properly choosing the amplifying factor ξ, we can increase the linearity of the modulation. The device is insensitive to the polarization state of the input light, so it should be used for intensity modulation of nonpolarized light with up to 100% modulation depth. The theoretical and experimental examination of the device is presented.     

Improved spatial phase detection for profilometry using a TDI imager

Performance of a time delay and integration (TDI) imager is analogous to a drum/periphery camera. Coupled to a modulated line generating laser diode, it is possible to use a TDI imager to encode the shape profile of a rotating cylindrical object as deformed gratings in a digital image. Among the various methods for extracting the phase from a deformed grating, the spatial phase detection (SPD) method is fast and easy to use. Errors are introduced in this method if the phase gradient is high over a grating interval. Here we propose a method to reduce the phase gradient by using a TDI feature which makes it possible to record images at variable lateral magnification.     

混合应变多量子阱波导结构设计

本文从理论上对混合应变量子结构（既有张应变量子阱又有压应变量子阱）的光学限制因子进行了讨论。由于垒层宽度较小，其变化量也不大，对光学影响相对小一些。当各层的折射率一定时，对称和非对称结构的最佳波导层厚度差不多，限制因子与波导层厚度的关系也类似，在最佳波导层厚度附近的区域，ГＴＭ／ГＴＥ比值变化对波导层厚比较敏感，这点可以用于偏振无关放大器的设计中，因为我们能够通过调节波导层厚度改变ＴＭ／ＴＥ模式增     

提高半导体器件欧姆接触可靠性的扩散阻挡层及其应用

为了提高半导体器件欧姆接触的可靠性，一般要在金属化系统中加扩散阻挡层。文中介绍了阻挡层的种类及其特性，并进行了比较和讨论。最后给出了在实际成功应用的例子。     

保偏光纤无源器件

随着保偏光纤制造工艺的成熟和性能的提高，保偏光纤的应用日益扩大。特别是在干涉型传感器等测量方面，利用保偏光纤的光无源器件起非常重要的作用，且种类很多。关于保偏光纤无源器件全面和系统的论述，至今报道的不多。本文就各种保偏光纤无源器件的工作原理、性能和制作方法进行了详细的论述。所阐述的保偏光纤无源器件有：保偏光纤耦合器、偏振分束器、保偏光纤偏振器、波分复用器、消偏器、波长板等。     

光纤无源器件的技术概况和发展趋势

光纤无源器件是光纤通信中的重要器件，也是新型的电子元件。它包括光纤（缆）连接器、光纤耦合器、波分复用器、光开关、光衰减器等。本文介绍了这些器件的技术概况和发展趋势。     

Dissipative Synthetic DNA‐Based Receptors for the Transient Loading and Release of Molecular Cargo

Supramolecular chemistry is moving into a direction in which the composition of a chemical equilibrium is no longer determined by thermodynamics but by the efficiency with which kinetic states can be populated by energy consuming processes. Herein, we show that DNA is ideally suited for programming chemically fueled dissipative self‐assembly processes. Advantages of the DNA‐based systems presented in this study include a perfect control over the activation site for the chemical fuel in terms of selectivity and affinity, highly selective fuel consumption that occurs exclusively in the activated complex, and a high tolerance for the presence of waste products. Finally, it is shown that chemical fuels can be used to selectively activate different functions in a system of higher complexity embedded with multiple response pathways.