Mach-Zehnder Interferometry Research Articles

Dynamics and density distribution of laser-produced Al plasmas using optical interferometry and optical emission spectroscopy

The dynamic evolution and density distribution of laser-produced plasmas (LPP) of Al in air at atmospheric pressure were investigated using optical interferometry and optical emission spectroscopy, respectively. Interferograms were obtained in Mach–Zehnder interferometry with a laser pulse energy of 35 mJ and delay times from 200 ns to 6.9 µs. From the shift in interference fringes within this time interval and Taylor–Sedow theory, the expansion profiles of the shock wave were found to be hemispherical and approached planar propagation. The expansion and evolution of the plasma plume were also studied by exploiting the phase shift and refractive index obtained from the interferograms using the fast Fourier transformation and Abel transformation. Three-dimensional spatial expansion profiles of the plasma plume and shock wave were presented. In addition, two-dimensional electron density distributions of the Al plasmas were obtained from the spatial dependence of the refractive index of plasma, and compared with the results of optical emission spectroscopy. The results from the two diagnostic methods and their advantages and disadvantages are discussed. This work exploits two diagnostic methods to study the dynamic evolution and the density distribution of the LPP in air at atmospheric pressure and provides an important base reference for developing LPP applications in many fields.

Double Imaging Mach–Zehnder Spatial Carrier Digital Shearography

ABSTRACTThis paper presents a Double Imaging Mach–Zehnder Spatial Carrier Digital Shearography (DIM-SCDS) system. Compared to traditional Spatial Carrier Mach–Zehnder shearography, DIM-SCDS has two advantages: one is that it can adjust shearing amount and spatial carrier frequency independently; the other one is that it can measure a larger area with a shorter working distance. Two pairs of imaging lenses and apertures are placed in the two arms of Mach–Zehnder interferometry, respectively. Shearing amount is adjusted by the mirrors in the two arms, and spatial carrier frequency is determined by the angle between the two apertures when they are mapped to the same optical axis. Shearograms of the object under test are recorded using a CCD. Shearogram phases are calculated as the measurement results. Finally, the performance of DIM-SCDS is proved by experiments.

Thermally induced dispersive optical bistability in silver nanosuspensions produced by pulsed laser ablation method

The thermally induced optical bistability in prepared silver (Ag) nanosuspensions have been studied experimentally, using Fabry–Perot and Mach–Zehnder interferometry methods. Two Ag nanosuspensions of different sizes were produced by different fluences of pulsed laser ablation method in distilled water. The pulsed Nd:YAG laser of 7 ns pulse width, 1064 nm wavelength and different fluences was employed to produce Ag nanosuspensions. Experimental observations were performed by an ultraviolet–visible–near infrared spectrophotometry. Structure and size of prepared Ag nanoparticles were diagnosed using transmission electron microscope images. Fabry–Perot and Mach–Zehnder interferometry methods were used to carry out the optical bistability process in prepared Ag nanosuspensions. In two considered interferometers, the obtained phase shifts of the hysteresis loops based on the optical bistability are inversely proportional to the nonlinear refractive index of samples and thickness of Ag nanosuspensions cells. Results indicate that the induced thermal effect of the optical bistability can be tuned by modifying parameters such as the nonlinear refractive index and applied interferometry methods. Hence, a desirable situation for the thermo-optical effects of the optical bistability can be easily realized in Ag nanosuspensions.

Ultra-wide-band structural slow light

The ability of using integrated photonics to scale multiple optical components on a single monolithic chip offers key advantages to create miniature light-controlling chips. Numerous scaled optical components have been already demonstrated. However, present integrated photonic circuits are still rudimentary compared to the complexity of today’s electronic circuits. Slow light propagation in nanostructured materials is a key component for realizing chip-integrated photonic devices controlling the relative phase of light and enhancing optical nonlinearities. We present an experimental record high group-index-bandwidth product (GBP) of 0.47 over a 17.7 nm bandwidth in genetically optimized coupled-cavity-waveguides (CCWs) formed by L3 photonic crystal cavities. Our structures were realized in silicon-on-insulator slabs integrating up to 800 coupled cavities, and characterized by transmission, Fourier-space imaging of mode dispersion, and Mach-Zehnder interferometry.

Nonlinear reflection of weak shock waves from a rough surface in air

Irregular reflection of weak acoustic shock waves occurs under the framework of the von Neumann paradox. In this study, the influence of the surface roughness on the reflection pattern was studied experimentally using spark-generated spherically divergent N-waves of 1.4 cm length reflecting from rigid rough surfaces in air. Dimensions of the roughness were varied from 20 up to 500 μm for different surfaces. A Mach-Zehnder interferometry method was used to reconstruct the pressure waveforms near the surface. The reconstruction was performed by applying the inverse Abel transform to the phase of the signal measured by the interferometer. It was shown that the height of the Mach stem became shorter for surfaces with larger dimensions of the roughness and disappeared when the surface roughness was large enough. Such tendency was also observed in simulations based on the Euler equations where the acoustic source was introduced as a Gaussian-envelope energy injection and the roughness was either sinusoidal or random and described by a Gaussian correlation function. [Work supported by RSF-17-72-10277 and by the Labex CeLyA of Universite de Lyon, operated by the French National Research Agency (ANR-10-LABX-0060/ ANR-11-IDEX-0007).]Irregular reflection of weak acoustic shock waves occurs under the framework of the von Neumann paradox. In this study, the influence of the surface roughness on the reflection pattern was studied experimentally using spark-generated spherically divergent N-waves of 1.4 cm length reflecting from rigid rough surfaces in air. Dimensions of the roughness were varied from 20 up to 500 μm for different surfaces. A Mach-Zehnder interferometry method was used to reconstruct the pressure waveforms near the surface. The reconstruction was performed by applying the inverse Abel transform to the phase of the signal measured by the interferometer. It was shown that the height of the Mach stem became shorter for surfaces with larger dimensions of the roughness and disappeared when the surface roughness was large enough. Such tendency was also observed in simulations based on the Euler equations where the acoustic source was introduced as a Gaussian-envelope energy injection and the roughness was either sinusoidal or r...

Optimal matter-wave gravimetry

We calculate quantum and classical Fisher informations for gravity sensors based on matterwave interference, and find that current Mach-Zehnder interferometry is not optimally extracting the full metrological potential of these sensors. We show that by making measurements that resolve either the momentum or the position we can considerably improve the sensitivity. We also provide a simple modification that is capable of more than doubling the sensitivity.

Experimental investigation of the effects of passivated aluminum nanoparticles on butane flame structure

This paper investigates the effects of aluminum nanoparticles on a premixed butane-air flame using optical methods. The experiments are performed for a range of equivalence ratios in rich/lean environments (0.8 ≤ φ ≤ 1.2) and laminar steady flame conditions (50 ≤ Re ≤ 200). The aluminum nanoparticles are added up to 5 wt%. The Mach-Zehnder interferometry technique and Schlieren photography method are applied to obtain the flame temperature and its laminar burning velocity. Addition of nanoparticles caused a higher temperature flame in most cases. Also, the laminar flame speed was affected positively by the aluminum nanoparticles. A maximum augmentation of 237 K was observed in the flame maximum temperature. Also, the laminar flame speed was enhanced by 18.9% and 29.1% in the cases of adding aluminum nanoparticles by 2 wt% and 5 wt%, respectively.

Direct measurement of the sound velocity in seawater based on the pulsed acousto-optic effect between the frequency comb and the ultrasonic pulse.

We present a new method to measure the velocity of sound in pure water and seawater using the Raman-Nath diffraction caused by acousto-optic effect between the optical frequency comb and the ultrasonic pulse. In the Mach-Zehnder interferometry system we established, the measurement and reference arms are tagged with sharp negative pulses caused by the pulsed ultrasound passing through them. The difference in optical path between the two parallel beams is twice the flight distance of the ultrasonic waves. The span between the two negative pulses reflects the time interval. At the same time, the distance between the two arms can be measured precisely using the femtosecond laser interferometry. Consequently, the time interval and the distance can be used to measure the sound velocity. The experimental results show that, the uncertainty of the sound speed measurement can achieve 0.03m/s@1482m/s in pure water and 0.029m/s@1527m/s in seawater, respectively, compared with the commercial sound velocity profiler (SVP). More importantly, benefiting from the faster and cleaner response of the acousto-optic effect than the piezoelectric effect which is widely adopted in direct sound velocity measurement method, our method provides a new idea for the metrology of sound velocity in seawater.

Design of an integrated optics for transglutaminase conformational change

Abstract A detailed theoretical research on a novel integrated optics with surface plasmon resonance (SPR)-based waveguide is presented. An SPR multilayer section is designed by introducing intermediate layers to support fundamental mode and stronger electromagnetic field. Most current techniques excited with a single optical mode are “blind” to the conformational change of bound molecules. The greatest strength of such technique lies in monitoring protein conformational change. The Mach-Zehnder interferometry architecture is adopted to maximize sensor sensitivity and prevent unspecific binding from biological material and error from geometrical difference. A proof-of-concept is conducted on the integrated optics by detecting protein transglutaminase (tTG) specifically binding calcium ion (Ca2+) via the finite-element method. The minimum decrease of biolayer thickness (δa =0.5 nm) caused by tTG-Ca2+ interaction is much smaller than a single protein molecule (normally 1–100 nm). Associated with biolayer thickness and density, a thin dense layer is formed as Ca2+ binds to the tTG protein. Thus, the tTG protein undergoing conformational change on binding Ca2+ is traced and verified as molecular interaction occurs.

Temperature field investigation of hydrogen/air and syngas/air axisymmetric laminar flames using Mach-Zehnder interferometry.

In this study, the optical method of Mach-Zehnder interferometry (MZI) is utilized in order to explore the flame structure and temperature field of syngas/air and hydrogen/air flames. Two axisymmetric burners with inner diameters of 4mm and 6mm are used for temperature field measurement of hydrogen and syngas, respectively. The effects of fuel composition, equivalence ratio, and Reynolds number (Re) are investigated at ambient condition (P=0.87 bar, T=300 K). Three different H2/CO fuel compositions with hydrogen fractions of 30%, 50%, and 100% are studied. Temperature profiles are reported at four different sections above the burner tip. Measured temperatures using the interferometry method are compared with thermocouple data and good agreement between them is observed. The results obtained in this investigation indicated that the MZI can be applied for accurate determination of flame front and temperature field, especially for high-temperature flames where other methods cannot be properly utilized. Analyses of the data reduction method revealed that the exact determination of the refractive index distribution and reference temperature is critical for accurate determination of the temperature field. The results indicated that by increasing the Re, the maximum flame temperature is enhanced. Increasing the equivalence ratio leads to expansion of the flame radial distribution (at the same distance from the burner tip). At higher distances from the burner tip, temperature increases uniformly from the flame boundary toward the flame axis, while at lower heights it shows reduction at the burner axis. By increasing the CO content of fuel, the maximum flame temperature increases at all equivalence ratios except at the stoichiometric condition, where SH100 illustrates the highest maximum flame temperature.

Persistent circular currents of exciton-polaritons in cylindrical pillar microcavities

We have experimentally observed an eddy current of exciton polaritons arising in a cylindrical GaAs/AlGaAs pillar microcavity under the nonresonant optical pumping. The polariton current manifests itself in a Mach-Zehnder interferometry image as a characteristic spiral that occurs due to the interference of the light emitted by an exciton-polariton condensate with a spherical wave artificially shaped from the emission of the same condensate. We have experimentally observed the condensates with the topological charges m = +1, m = -1 and m = -2. The interference pattern corresponding to the m = -2 current represents the twin spiral emerging from the center of the micropillar.

Rapid growth of ice crystal dendrite tips in dilute solution of trehalose

We use Mach-Zehnder interferometry to measure ice-crystal tip radii and growth rates in dilute aqueous solutions of trehalose over a range of concentrations. Although trehalose at high concentrations is a well-known inhibitor of ice crystal growth in aqueous solution, we find that the ice instead grows faster with the trehalose concentrations below about 8 wt%, with a peak tip velocity near 2 wt%. By directly measuring the 3D morphology of the growing ice crystals with the interferometer, we find that the dendrite tip in solution becomes thinner and sharper than that in pure water, causing the more rapid growth of ice.

An experimental and numerical study on the combustion and flame characteristics of hydrogen in intersecting slot burners

In the present study, two impinging slot jets of hydrogen gas at different angles and distances are investigated experimentally using the Mach-Zehnder interferometry. The obtained temperatures from the interferometry method were validated against the thermocouple measurements. The generated temperature field is studied using infinite fringe interferometry. Slot burners with high length-to-width ratio are utilized to ensure producing a uniform 2D flow. The slot burners' angle and the distance between the burners are varied from 60 to 100° and 10 mm–25 mm in the increment of 20° and 5 mm, respectively. The Reynolds number is varied from 70 to 150, and the equivalence ratio is changed from 0.8 to 2.5. The results indicated that the Reynolds number does not have a considerable effect on increasing the maximum temperature, while, it has a significant influence on the flame structure. The equivalence ratio has a substantial effect on both maximum temperature and flame structure. Also, the variations in angle of burners have a considerable effect on the flame stability. Furthermore, the distance of burners strongly affects the maximum flame temperature and the flame structure. It was observed that by increasing the burners distance, the domain of maximum temperature is descended. The results from numerical modeling were also validated with experiments. The effect of temperature on the NOx emissions was clearly shown in the CFD simulations.

Azimuth-Rotated Splicings of a Four-Core Optical Fiber for Inter-Core Group Delay Compensation

This letter presents an experimental method to compensate for the differential group delay between the core modes in a multi-core fiber. Optical fiber sections are sequentially spliced with azimuthal offsets such that light initially launched to any cores can propagate through the combination of the same lengths of different cores, resulting in ideally uniform group delay. The differential group delays before and after the compensation are measured by wavelength-domain Mach–Zehnder interferometry through multi-core fiber sections. The experimental results show that the group delay compensation is practically limited by non-uniformity of the multi-core fiber.

Adiabatic Mach–Zehnder interferometer in a dipolar spin-1 condensate

We propose and analyze a realizable scheme for performing a Heisenberg-limited Mach–Zehnder interferometry with a dipolar spin-1 condensate. Based upon adiabatic processes of sweeping the transverse magnetic field, we demonstrate a perfect phase transition, which accomplishes the beam splitter, phase shifter and recombiner as for a Mach–Zehnder interferometer. The attractive dipolar interaction ensures the existence of a path-entangled state which enhances the phase measurement precision to the Heisenberg limit. We also study the spin squeezing of the state generated in the beam splitter and show that the spin squeezing exhibits an extremum near the critical point of phase transition.

Two-dimensional interferometric characterization of laser-induced refractive index profiles in bulk Topas polymer

In this paper we precisely determine laser-induced refractive index profiles created in cyclic olefin copolymer Topas 6017 employing a sophisticated phase shifting Mach-Zehnder interferometry approach. Beyond the usual one-dimensional modification depth measurement we highlight that for straight waveguide structures also a two-dimensional refractive index distribution can be directly obtained providing full information of a waveguide's exact cross section and its gradient refractive index contrast. Deployed as direct data input in optical waveguide simulation, the evaluated 2D refractive index profiles permit a detailed calculation of the waveguides' actual mode profiles. Furthermore, conventional one-dimensional interferometric measurements for refractive index depth profiles with varying total imposed laser fluence of a 248 nm KrF excimer laser are included to investigate the effect on refractive index modification depth. Maximum surface refractive index increase turns out to attain up to 1.86·10−3 enabling laser-written optical waveguide channels. Additionally, a comprehensive optical material characterization in terms of dispersion, thermo-optic coefficient and absorption measurement of unmodified and UV-modified Topas 6017 is carried out.

Label-free detection of the IL-6 and IL-8 interleukines through monolithic silicon photonic chips and simultaneous dual polarization optics

A silicon microphotonic chip with ten monolithically integrated interferometers and an equal number of light sources is employed for the label-free and multiplexed detection of two proteins of the cytokine family. The chip implements broad-band Mach-Zehnder interferometry and is used for the detection of the IL-6 and IL-8 interleukins. The silicon transducer is made through mainstream silicon technology and integrates avalanche diode based white light LEDs and monomodal waveguides forming Mach-Zehnder interferometers. The light spectrum is modulated through the interferometer and the spectrally resolved interference fringes are monitored by a digital spectrometer. Biomolecular built-up on the sensing arm causes pattern shifts that are evaluated through Fourier Transform. The microsystem level set-up includes microfluidic components, direct contacting of the chip contact pads through spring loaded pins and alignment guides and a spectrometer. The dual polarization optics allows the simultaneous derivation of the TE and TM sensitivity plots and the calculation of the refractive indices of either protein.

Experimental investigation on temperature field and heat transfer distribution of a slot burner methane/air flame impinging on a curved surface

Experiments have been performed to obtain the temperature field and Nusselt number for a methane/air slot flame impinging into a cylindrical surface. Mach-Zehnder interferometry was used to determine the temperature. The effects of operation conditions including Reynolds number, equivalence ratio, distance between the burner and impingement surface, and the surface diameter were investigated. Results show that by decreasing the diameter of impingement surface, maximum heat flux increases and the location of maximum heat flux moves from the stagnation point towards the wall jet region. Increasing the Reynolds number creates a considerable heat flux both in the stagnation and the wall jet region. Equivalence ratio is the most effective parameter on the maximum flame temperature. Reducing the distance between the burner and impingement surface increases the heat flux, but, if the impingement surface is located through the inner reaction zone of flame, the heat flux decreases around the stagnation region.

Magnetomigration of Rare-Earth Ions Triggered by Concentration Gradients.

Mach-Zehnder interferometry was applied to explore the effects of inhomogeneous magnetic fields on the mobility of rare-earth ions in aqueous solutions. No migration of ions was observed in a thermodynamically closed system when a homogeneous solution was subjected to a magnetic field gradient alone. However, magnetomigration could be triggered by a concentration gradient of the rare-earth ions in the solution. When a concentration gradient was introduced in the sample by solvent evaporation, consistent migration of paramagnetic Dy3+ ions from the bulk solution to regions with stronger magnetic fields was observed. By contrast, no movement was detected for diamagnetic Y3+ ions in the presence of a concentration gradient.

Ignition of a hydrogen–air mixture by low voltage electrical contact arcs

This article presents an experimental and computational study of ignition caused by a low voltage electrical contact arc. The contact arc is a transient electrical discharge which occurs due to movement of electrical contacts, for example, when two energised electrodes are separated. The physical properties of this discharge are significantly different from the more conventional high voltage spark. Its potential to cause ignition is an important consideration in international explosion protection standards. As these standards are based on unreliable empirical methods, a more fundamental investigation is warranted. This study uses a specially designed apparatus and electrical circuit to create the contact arc in a hydrogen–air mixture. The transient development of the resulting flame kernel is observed using Mach–Zehnder interferometry with high spatial and temporal resolution. These experimental results are compared to simulations of a 3-D reactive flow model with detailed chemical kinetics and molecular transport. A quantitative comparison is effected by the generation of synthetic optical phase plots from the simulation output. This comparison showed reasonable correspondence between the simulated and measured flame shape. Ignition delays and thresholds were, however, under-predicted by the model. The comparison was complicated by significant statistical scattering in the experimental results. Additional investigations into the sensitivity of the model showed good robustness to grid size variations, and that inclusion of a simplified consideration of heat transfer through the electrodes produces small differences in flame shape and ignition delay.