基于3×3耦合器的马赫-曾德尔干涉仪的光纤光栅波长解调技术

介绍了一种基于3×3和2×2光纤耦合器构成的非平衡马赫-曾德尔干涉仪的波长解调方案。理论分析和数据对比表明，相对于由两个2×2光纤耦合器构成的马赫-曾德尔干涉仪，本干涉仪具有宽谱的灵敏度、能跟踪波长的变化方向和相位展开的优点，实验方案用于测量固定在悬臂梁上的传感光纤布拉格光栅（FBG）的峰值波长变化，获得了±1pm的静态波长解调精度，在10Hz处的动态分辨率为27nε/√Hz。相位展开算法使得应变测量范围达到了2014με，对应的相位变化为3．22π。

A phase-shifting vectorial-shearing interferometer with wedge plate phase-shifter

We present a novel phase-shifting vectorial-shearing interferometer with a wedge plate phase-shifter. The interferometer is based on a modified Mach-Zehnder configuration; the common-path nature makes it capable of testing the wavefront of a short coherence-length light source, such as a laser diode. Vectorial shear (shearing in the x and y directions simultaneously) in an arbitrary direction is introduced by inserting two wedge plates orthogonally in two arms, respectively. One of the wedge plates is split into two parts (parallel part and wedge part); phase shift is produced by moving the wedge part in contact along the parallel part. The moving distance for a 2 pi phase shift is a few millimetres in specific conditions. The wedge plate phase-shifter increases the moving distance for phase shift and makes the control of phase shift relatively easy. We also discuss the lateral shear error and phase shift errors induced by wedge plates. The lateral shear error is small enough to be ignored; the phase shift error is determined mainly by the wedge angle error. Lastly, we give the experimental results of phase-shifting interference fringes in vectorial shear mode.

A new method of measuring the waveguide dispersion factor and the thermo-optic coefficient of long-period fiber gratings

Based on the Mach-Zehnder effect between the core mode and the cladding modes, the interference fringes are formed by a pair of cascaded long-period fiber gratings (CLPFGs). Theoretical analyses show that the spectral spacing and the wavelength of these fringes are functions of the waveguide dispersion factor gamma, which is a characterizing parameter to LPFG and with theoretical and applicational significance. By measuring the characteristics of the transmission spectra of CLPFGs, the absolute value of gamma can be obtained. At the same time, the thermo-optic coefficient of effective refractive index difference between core and cladding modes, p, can also be obtained by measured the temperature sensitivity of these fringes. In the experiments, \gamma\ and mu were measured by this method to be 0.874 and 4.08 x 10(-5) degreesC(-1), respectively, for LPFGs with period of 450 mum and with a HE14 resonant peak at 1554 nm. (C) 2004 Elsevier B.V. All rights reserved.

Quantitative measurement of domain inversion in RuO2 : LiNbO3 crystal by digital holographic interferometry

We quantitatively study the domain inversion in a RuO2:LiNbO3 crystal wafer by the digital holographic interferometry. The crystal wafer is placed into one arm of a Mach-Zehnder-type interferometer to record a series of holograms. Making use of the angular spectrum backward propagation algorithm, we reconstruct the optical wave field in the crystal plane. The extracted phase difference from the reconstructed optical wave field is a well linear function of the applied external voltage. We deduce that the linear electro-optic coefficient of the detected RuO2:LiNbO3 crystal sample is 9.1x10(-12) m/V. An unexpected phase contrast at the antiparallel domain wall is observed and the influence of the applied external voltage on it is studied in detail. Also the built-in internal field is quantitatively measured as 0.72 kV/mm. (c) 2006 American Institute of Physics.

利用数字全息干涉术观察RuO2：LiNbO3晶体中畴反转的区域特性

利用马赫-曾德尔干涉光路和V光学透镜系统，以部分畴反转的掺钌铌酸锂晶体（RuO2：LiNbO3）的透射光作为物光来记录全息图，并在数值再现过程对其进行频域滤波以实现物场波前信息的数值重建，检测出在一定电压作用下晶体内部折射率变化的二维分布．检测结果证实;晶体中发生畴反转的区域与发生电色效应的区域严格相符．数字全息干涉术非接触、无干扰、无破坏的优势在准实时监控、检测和分析铌酸锂晶体畴反转方面有很好的应用前景．

马赫-曾德尔型相移矢量剪切干涉仪

为了实现对激光波面的等光程测试，设计了一个新颖的相移矢量剪切干涉仪。该干涉仪以马赫一曾德尔结构为基础，为等光程干涉仪。通过在相干的两路光束中分别插入楔角方向正交放置的楔板实现矢量剪切；其中一块楔板分成两块（平板部分和楔板部分），楔板部分沿平板部分的表面移动，通过改变光程差来实现相移，2π相移所需的移动距离为几毫米的量级，该相移方法在相移精度控制上比较简单。文中还对楔板引入的横向剪切误差和相移误差进行了分析，最后给出了实验所得的一组相移干涉图。

利用脉冲重复率倍增和时域泰伯效应实现毫米波脉冲的产生

我们提出了一种新颖的利用脉冲重复率倍增和时域泰伯效应实现毫米波脉冲信号产生的光学方法。在我们的方案中，一个级联的马赫振德干涉仪被用来实现脉冲重复率倍增，一个线性的啁啾光纤光栅被用来实现时域泰伯效应。文中对这种方法的基本理论进行了分析，并给出了相应的数值模拟的结果。研究结果显示这种灵活的毫米波脉冲信号产生的方案在未来的宽带的Radio over Fiber技术将有一个很好的潜在的应用。

Experimental demonstration of femtosecond switching of a fully packaged all-optical switch

We experimentally demonstrate femtosecond switching of a fully packaged hybrid-integrated Mach-Zehnder switch. A record switching window of 620fs at fult-width-half-maximum is achieved. © 2004 Optical Society of America.

250 MHz repetition rate monolithically integrated modulated mode-locked semiconductor laser

We present the first monolithically integrated semiconductor pulse source consisting of a mode-locked laser diode, Mach-Zehnder pulse picker, and semiconductor optical amplifier. Pairs of 5.6 ps pulses are generated at a 250 MHz repetition rate. © 2012 OSA.

Variable repetition rate monolithically integrated mode-locked-laser- modulator-MOPA device

A monolithically integrated MLLD-modulator-MOPA is presented generating 12.5 ps pulses. The Mach-Zehnder modulator allows tunable repetition rates from 14 GHz to 109 MHz, and the MOPA boosts the peak power by 3.2 dB. © 2012 IEEE.

Scalable, low-energy hybrid photonic space switch

A scalable monolithically integrated photonic space switch is proposed which uses a combination of Mach-Zehnder modulators and semiconductor optical amplifiers (SOAs) for improved crosstalk performance and reduced switch loss. This architecture enables the design of high-capacity, high-speed, large-port count, low-energy switches. Extremely low crosstalk of better than -50 dB can be achieved using a 2 × 2 dilated hybrid switch module. A 'building block' approach is applied to make large port count optical switches possible. Detailed physical layer multiwavelength simulations are used to investigate the viability of a 64 × 64 port switch. Optical signal degradation is estimated as a function of switch size and waveguide induced crosstalk. A comparison between hybrid and SOA switching fabrics highlights the power-efficient, high-performance nature of the hybrid switch design, which consumes less than one-third of the energy of an equivalent SOA-based switch. The significantly reduced impairments resulting from this switch design enable scaling of the port count, compared to conventional SOA-based switches. © 1983-2012 IEEE.

Monolithic MZI-SOA hybrid switch for low-power and low-penalty operation.

We report the first experimental demonstration of a monolithically integrated hybrid dilated 2×2 modular optical switch using Mach-Zehnder modulators as low-loss 1×2 switching elements and short semiconductor optical amplifiers to provide additional extinction and gain. An excellent 40 dB cross-talk/extinction ratio is recorded with data-modulated signal-to-noise ratios of up to 44 dB in a 0.1 nm bandwidth. A switching time of 3 ns is demonstrated. Bit error rate studies show extremely low subsystem penalties of less than 0.1 dB, and studies indicate that, by using this hybrid switch building block, an 8×8 port switch could be achieved with 14 dB input power dynamic range for subsystem penalties of less than 0.5 dB.

Experimental demonstration of femtosecond switching of a fully packaged all-optical switch

We experimentally demonstrate femtosecond switching of a fully packaged hybrid-integrated Mach-Zehnder switch. A record switching window of 620fs at full-width-half-maximum is achieved. © 2004 Optical Society of America.

Interaction between the intrinsic second- and third-order optical fields in an Al0.53Ga0.47N/GaN heterostructure

We present an experimental demonstration of the interaction between the intrinsic second- and third-order optical fields in an Al0.53Ga0.47N/GaN heterostructure. The sample was deposited by metal-organic chemical vapor deposition on (0001) sapphire. The nonlinear optical coefficients of the sample, which were measured with a Mach-Zehnder interferometer system, quadratically increase with the applied modulating voltage, indicating the existence of the third-order optical field. The third-order signal was then detected by the Z-scan method and we calculated the built-in dc field on the AlGaN/GaN interface to confirm the strong interaction between the intrinsic second- and third-order optical fields. (c) 2008 American Institute of Physics.

High-speed 2 x 2 silicon-based electro-optic switch with nanosecond switch time

A 2 x 2 electro-optic switch is experimentally demonstrated using the optical structure of a Mach-Zehnder interferometer (MZI) based on a submicron rib waveguide and the electrical structure of a PIN diode on silicon-on-insulator (SOI). The switch behaviour is achieved through the plasma dispersion effect of silicon. The device has a modulation arm of I mm in length and cross-section of 400 nmx340 nm. The measurement results show that the switch has a V pi L pi figure of merit of 0.145 V-cm and the extinction ratios of two output ports and cross talk are 40 dB, 28 dB and -28 dB, respectively. A 3 dB modulation bandwidth of 90 MHz and a switch time of 6.8 ns for the rise edge and 2.7 ns for the fall edge are also demonstrated.