Correction to: Dynamic Mach–Zehnder interferometer based on a Michelson configuration and a cube beam splitter system

Optical Review - The article Dynamic Mach–Zehnder interferometer based on a Michelson configuration and a cube beam splitter system written by A. Montes...     

Refractometer based on a tapered Mach–Zehnder interferometer with Peanut-Shape structure

A novel refractometer based on tapered Mach–Zehnder modal interferometer (MZI) is proposed and experimentally demonstrated. This sensor is composed of a pair of Peanut-Shape structures and an embedded taper – the former excites high-order cladding modes, while the latter enhances the evanescent field. As the effective refractive index (RI) of cladding is based on the changes of surrounding RI, thus extinction ratio will change due to the alteration of the distribution of power in the fiber which is induced by various differences of core and cladding for RI. As a result, the maximum RI sensitivity of 240.78 extinction ratio/RIU (refractive index unit) is achieved within the range from 1.3334 to 1.4081.     

Signal amplification based on the local nonlinear Mach–Zehnder interferometer

Using the phase modulation of spatial solitons, a new scheme for all-optical signal amplification has been proposed in this paper. The considered structure is composed of the nonlinear Mach–Zehnder interferometer (NMZI) with the straight control waveguide (CWG), the uniform nonlinear medium (NLM) and the linear output waveguide. The local NMZI functions like a phase shifter. The light-induced index changes in the local nonlinear MZI are responsible for the input beam routing in the uniform nonlinear medium. The coupling of the input beam to the output waveguide depends on its propagation direction in the NLM. It is shown that the signal launched at CWG can deflect the beam launched at the NMZI (input beam) and a modulated (amplified) output could be obtained at the output waveguide. Further, signal pulse may be reshaped by appropriately increasing the NLM length. In addition, amplification factor may be enhanced by increasing the NLM length and injecting an appropriate continuous wave beam along with the signal beam at CWG.     

Stable multi-wavelength thulium-doped fiber laser based on all-fiber Mach–Zehnder interferometer

We propose and experimentally demonstrate a multi-wavelength thulium-doped fiber（TDF） laser based on all-fiber Mach–Zehnder interferometer（MZI） at 1.9 mm. Here a segment of 4 m single-mode TDF is pumped by 1568 nm fiber laser for 2 mm band optical gain. The MZI includes two cascaded 3 d B coupler. A segment of 3.5 m long un-pumped polarization-maintaining TDF and polarization controller（PC） are joined in the ring cavity to suppress the mode competition. Multi-wavelength lasers at 1.9 mm with wavelength number from one to four are obtained by adjusting the PC and the stability of output power of multi-wavelength fiber laser is analyzed.     

In-fiber Mach–Zehnder interferometer based on multi-mode fiber and up-taper for curvature sensing

A new type of curvature sensor comprises a stub of multi-mode fiber and an up-taper is proposed and demonstrated experimentally. The whole fabrication process is quite simple and the sensor head is cost effective. Measurement results show that it has a maximum curvature sensitivity of −61.877 nm/m⁻¹ at 1.1718 m⁻¹ (the highest value of reported papers among in-fiber Mach–Zehnder interferometers) and −9.2115 nm/m⁻¹ from 0.865 m⁻¹ to 1.1172 m⁻¹. Temperature sensitivity of 89.01 pm/°C within the range of 20–80 °C has also been achieved, which implies the possibility for measurement of temperature.     

Graphene-based Mach–Zehnder nanophotonics interferometer working as a splitter/switch and as a multiplexer/demultiplexer

We developed and are presenting a graphene-based nanophotonic Mach–Zehnder Interferometer (MZI), which can operate as a signal follower, switch and splitter and as a multiplexer/demultiplexer. Due to the excellent electrical/optical parameters inherent to the graphene, we showed that the device we are presenting can works in several different ways, which can not be supported by MZI based on conventional materials. It is worth mentioning that the operations of the device we have developed take into account the electrical/optical parameters of the graphene, which provide greater versatility and efficiency compared to the MZIs manufactured with conventional materials. In addition, these parameters can be controlled via, for example, gate voltage, so that many operations can be performed in parallel, which is also not possible through the use of conventional materials. Due to its manometric dimensions, this MZI can be integrated within photonic integrated circuits, so that we can use this device in dense wavelength division multiplexing optical communications.     

A Mach–Zehnder interferometer based on peanut structure for temperature and refractive index measurement

Optical Review - A fiber Mach–Zehnder (M-Z) interferometer based on the peanut structure is proposed to measure the temperature and the refractive index (RI). This design includes the...     

Pulse generation and compression using an asymmetrical porous silicon-based Mach–Zehnder interferometer configuration

We propose an asymmetrical Mach–Zehnder interferometer (MZI) for efficient pulse generation and compression using porous silicon (PS) waveguide, fibre delay line and couplers. We show a pulse compression of about 0.4 ns at the output port with third-order super-Gaussian input pulse in ～2 ns time duration and ～40.3 W peak power level. Also, we show the possibility of obtaining compressed single- or double-pulse with judicious choice of various parameters like input peak power, delay time and input pulse width.     

Transmission characteristics of Mach–Zehnder interferometer comb filter based on thermal operation

We propose and experimentally demonstrate switchable and tunable transmission characteristics of a Mach–Zehnder interferometer comb filter based on thermal operation. Its temperature characteristics are investigated to reveal a shift in the peak wavelength position from 0.003 to 0.004 nm/°C and a tunable range of wavelength spacing of 0.76–0.90 nm for maximum and minimum effective lengths, respectively. This configuration provides the unique advantages of an all-fiber structure, tunable wavelength spacing, switchable spectral peaks, independent tuning of the center wavelength and wavelength spacing of the spectral peaks, and low polarization sensitivity. It is relatively simple to fabricate and expected to have applications in temperature fiber optic sensors and multiwavelength fiber laser sources.     

Temperature-insensitive refractive index sensor based on Mach–Zehnder interferometer with two microcavities

We propose a temperature-insensitive refractive index(RI) fiber sensor based on a Mach–Zehnder interferometer. The sensor with high sensitivity and a robust structure is fabricated by splicing a short photonic crystal fiber(PCF) between two single-mode fibers, where two microcavities are formed at both junctions because of the collapse of the PCF air holes. The microcavity with a larger equatorial dimension can excite higher-order cladding modes, so the sensor presents a high RI sensitivity, which can reach 244.16 nm/RIU in the RI range of1.333–1.3778. Meanwhile it has a low temperature sensitivity of 0.005 nm/°C in the range of 33°C–360°C.     

All-fiber intermodal Mach–Zehnder interferometer based on a long-period fiber grating combined with a fiber bitaper

We report a novel all-fiber narrow-bandwidth intermodal Mach–Zehnder interferometer (MZI) based on a long-period fiber grating (LPFG) combined with a fiber bitaper, and the MZI has no special limit for the resonant wavelength of the LPFG. Its responses to temperature and axial strain are studied theoretically and experimentally. Experimental results indicate that the temperature sensitivity is 0.0585 nm/°C within the temperature range from 30 °C to 90 °C and the axial strain sensitivity of 0.00013 nm/με can be neglected. Furthermore, as only the common single-mode fiber (SMF) is required during the fabrication process, the proposed device is cost effective and has good practicability in the optical sensing systems.     

High sensitivity Mach–Zehnder interferometer sensors based on concatenated ultra-abrupt tapers on thinned fibers

This study proposes a simple, cost-effective method to fabricate fiber-based Mach–Zehnder interferometer (MZI) sensors by concatenating two ultra-abrupt fiber tapers together using a fusion splicer. By concatenating, the taper diameter and length ratio is 1:1 that is much greater than that (1:10) by stretching. The refractive index sensitivity is comparable to the MZI sensors based on long-period fiber grating pairs or stretched fiber taper pairs. The MZI fiber claddings are etched to improve the sensitivity of refractive index measurements. The sensitivity is 664.57 nm/RIU (refractive index unit) for the refractive index ranging from 1.3348 to 1.3558, which is 2–6 times greater than those measured by long period fiber gratings (LPFGs) after sensitivity enhancement.     

Optical fiber strain and temperature sensor based on an in-line Mach–Zehnder interferometer using thin-core fiber

We propose and demonstrate a fiber in-line Mach–Zehnder interferometer using thin-core fibers. This in-line interferometer is composed of a short section of thin-core fiber inserted between two single mode fibers (SMF), and demonstrated as a strain and temperature sensor in this study. A strain sensitivity of ?1.83 pm/με with a measurement range of 0?2000 με, and the temperature sensitivity of ?72.89 pm/°C with a temperature variation of 50 °C are achieved. We also discussed that the influence of strain and temperature change on the relative power ratios among the excited cladding modes in thin-core fibers.     

Spectra in nested Mach–Zehnder interferometer experiments

By the means of the standard quantum mechanics formalism I present an explicit derivation of the structure of power spectra in Danan et al. and Zhou et al. experiments with nested dynamically changing Mach–Zehnder interferometers. The analysis confirms that we observe prominent, first-order peaks on frequencies related to some of the elements of the interferometer, but not on others. However, as I shall demonstrate, there are also other, weaker effects related to all relevant elements of the setup. In case of the Danan et al. setup, there are even peaks at all frequencies of element oscillations. When confronted in an experiment, these observations shall challenge the interpretation of the experiments based on anomalous trajectories of light.     

Ultrafast all-optical demultiplexer based on monolithic Mach–Zehnder interferometer with integrated semiconductor optical amplifiers

A monolithically integrated and fully packaged Mach–Zehnder interferometer with semiconductor optical amplifiers (MZI-SOA) is demonstrated as polarisation-independent high-speed demultiplexer for up to 160 Gbit/s optical time division multiplexed (OTDM) data streams.     

Using a Mach–Zehnder interferometer to deduce nitrogen density mapping

This work presents an optical method using the Mach–Zehnder interferometer. We especially diagnose a pure nitrogen gas subjected to a point to plane corona discharge, and visualize the density spatial map. The interelectrode distance equals6 mm and the variation of the optical path has been measured at different pressures: 220 Torr, 400 Torr, and 760 Torr.The interferograms are recorded with a CCD camera, and the numerical analysis of these interferograms is assured by the inverse Abel transformation. The nitrogen density is extracted through the Gladstone–Dale relation. The obtained results are in close agreement with values available in the literature.     

Simultaneous measurement of refractive index and temperature using thinned fiber based Mach–Zehnder interferometer

A novel method for simultaneous measurement of refractive index and temperature based on a small core and cladding diameters thinned fiber Mach–Zehnder interferometer (MZI) using singlemode-multimode-thinned-multimode-singlemode (SMTMS) fiber structure is proposed. Experiments indicate that the selected two interference orders have sensitivities of ?16.1936 nm/RIU and 0.0534 nm/°C, and ?23.0473 nm/RIU and 0.0575 nm/°C, respectively, among RI range from 1.3325–1.3720 and temperature range from 22 °C–82 °C. We can thus use the coefficient matrix of these two peaks to simultaneously determine the surrounding refractive index and temperature. The fabrication is easy, safe and cost effective, includes only the fusion splicing, making the device properly attractive for practical sensor applications.     

Mach–Zehnder interferometer with squeezed and EPR entangled optical fields

We study a scheme for Mach-Zehnder(MZ) interferometer as a quantum linear device by injecting two-mode squeezed input states into two ports of interferometer.Two-mode squeezed states can be changed into two types of inputs for MZ interferometer:two squeezed states and Einstein-Podolsky-Rosen(EPR) entangled states.The interference patterns of the MZ interferometer vary periodically as the relative phase of the two arms of the interferometer is scanned,and are measured by the balanced homodyne detection system.Our experiments show that there are different interference patterns and periodicity of the output quantum states for two cases which depend on the relative phase of input optical fields.Since MZ interferometer can be used to realize some quantum operations,this work will have the important applications in quantum information and metrology.     

Multi-ion Mach–Zehnder interferometer with artificial nonlinear interactions

We propose a method to implement a Mach-Zehnder interferometry based upon a string of trapped ions with artificial nonlinear interactions. By manipulating the coupling strength between two involved internal states of the ions, we could achieve the beam splitting/recombination with NOON states. Using current techniques for manipulating trapped ions, we discuss the experimental feasibility of our scheme and analyze some undesired uncertainty under realistic experimental environment.     

Creating λ /3 focal holes with a Mach–Zehnder interferometer

We report the formation of doughnut-shaped focal intensity distributions with hole diameters of /3.3=232 nm full-width-at-half-maximum. The doughnut shape is created by illuminating a high-numerical-aperture lens with the output of a Mach–Zehnder interferometer, in which half of the wavefront in each arm is phase retarded by . The focal intensities are probed with a point-like scatterer and compared with the predictions of a vectorial focusing theory. The orientation of the phase-discontinuity line with respect to the electric field determines whether a strong longitudinal or a vanishing electric field is produced at the focal point. Conditions are given for creating high-contrast focal holes at the sub-micron scale. PACS 42.25.-p; 42.30.-d; 42.79.-e