Showing papers on "Mach–Zehnder interferometer published in 2018"

High-Performance Hybrid Silicon and Lithium Niobate Mach-Zehnder Modulators for 100 Gbit/s and Beyond

Abstract: Optical modulators are at the heart of optical communication links Ideally, they should feature low insertion loss, low drive voltage, large modulation bandwidth, high linearity, compact footprint and low manufacturing cost Unfortunately, these criteria have only been achieved on separate occasionsBased on a Silicon and Lithium Niobate hybrid integration platform, we demonstrate Mach-Zehnder modulators that simultaneously fulfill these criteria The presented device exhibits an insertion loss of 25 dB, voltage-length product of 22 Vcm, high linearity, electro-optic bandwidth of at least 70 GHz and modulation rates up to 112 Gbit/s The high-performance modulator is realized by seamless integration of high-contrast waveguide based on Lithium Niobate - the most mature modulator material - with compact, low-loss silicon circuits The hybrid platform demonstrated here allows for the combination of 'best-in-breed' active and passive components, opening up new avenues for enabling future high-speed, energy efficient and cost-effective optical communication networks

0.52 V mm ITO-based Mach-Zehnder modulator in silicon photonics

Abstract: Electro-optic modulators transform electronic signals into the optical domain and are critical components in modern telecommunication networks, RF photonics, and emerging applications in quantum photonics, neuromorphic photonics, and beam steering All these applications require integrated and voltage-efficient modulator solutions with compact form factors that are seamlessly integrable with silicon photonics platforms and feature near-CMOS material processing synergies However, existing integrated modulators are challenged to meet these requirements Conversely, emerging electro-optic materials heterogeneously and monolithically integrated with Si photonics open up a new avenue for device engineering Indium tin oxide (ITO) is one such compelling material for heterogeneous integration in Si exhibiting formidable electro-optic effect characterized by unity-order index change at telecommunication frequencies Here we overcome these limitations and demonstrate a monolithically integrated ITO electro-optic modulator based on a Mach Zehnder interferometer featuring a high-performance half-wave voltage and active device length product of VπL = 052 V mm We show that the unity-strong index change enables a 30 μm-short π-phase shifter operating ITO in the index-dominated region away from the epsilon-near-zero point for reduced losses This device experimentally confirms electrical phase shifting in ITO enabling its use in applications such as compact phase shifters, nonlinear activation functions in photonic neural networks, and phased array applications for LiDAR

All-optical XOR, NOR, and NAND logic functions with parallel semiconductor optical amplifier-based Mach-Zehnder interferometer modules

Abstract: The performance of XOR, NOR, and NAND functions implemented all-optically (AO) using two parallel semiconductor optical amplifier (SOA)-based Mach-Zehnder interferometers is simulated and investigated. The dependence of the quality factor on key input signals and SOAs parameters is investigated and assessed. The obtained results show that the target AO Boolean functions can simultaneously be realized with the employed scheme with both logical correctness and high quality at 80 Gb/s.

16 × 16 Silicon Optical Switch Based on Dual-Ring-Assisted Mach–Zehnder Interferometers

Abstract: In this paper, we report a nanosecond 16 × 16 silicon electro-optic switch chip based on a Benes architecture. The switch adopts dual-ring-assisted Mach–Zehnder interferometers as the basic building blocks. In each switch element, both TiN microheaters and PIN diodes are integrated for ring resonance alignment and high-speed switching, respectively. A transfer-matrix-based theoretical model is established to analyze the switch performances. The 16 × 16 switch is characterized by measuring the optical transmission spectra and quadrature phase-shift keying (QPSK) data transmission through 16 representative optical paths. The insertion loss of the entire switch chip is 10.6 ± 1.7 dB and the crosstalk is less than −20.5 dB. The 32-Gb/s QPSK signal is successfully switched to different destination ports by reconfiguring the optical paths, verifying the signal integrity after switching.

Polarization-insensitive 2 × 2 thermo-optic Mach-Zehnder switch on silicon.

Abstract: A polarization-insensitive 2×2 thermo-optic Mach–Zehnder switch (MZS) on silicon is proposed and demonstrated experimentally by utilizing silicon-on-insulator (SOI) nanophotonic waveguides with a 340-nm-thick silicon core layer. The present MZS consists of two 2×2 3 dB multimode interference (MMI) couplers, which are designed to be polarization-insensitive by choosing the core width optimally. Meanwhile, the MZS arms are designed with square SOI nanophotonic waveguides with a cross section of 340 nm×340 nm in order to achieve polarization-insensitive phase shift. The fabricated silicon MZS has an excess loss of 1∼4 dB and an extinction ratio of >20 dB in the C-band (1530∼1565 nm) for both TM and TE polarizations.

In-Line Mach-Zehnder Interferometer With D-Shaped Fiber Grating for Temperature-Discriminated Directional Curvature Measurement

Abstract: A high-sensitivity curvature sensing configuration is implemented by using a fiber Mach-Zehnder interferometer (MZI) with D-shaped fiber Bragg grating (FBG). A segment of D-shaped fiber is fusion spliced into a single mode fiber at both sides, and then a short FBG is inscribed in the D-shaped fiber. The fiber device yields a significant spectrum sensitivity as high as 87.7 nm/m−1 to the ultralow curvature range from 0 to 0.3 m−1 , and can distinguish the orientation of curvature experienced by the fiber as the attenuation dip producing either a blue or red wavelength shift, by virtue of the asymmetry of D-shaped fiber cladding. In addition, by tracking both resonant wavelengths of the MZI and embedded FBG, the temperature and curvature can be measured simultaneously.

A Novel Strain Sensor with Large Measurement Range Based on All Fiber Mach-Zehnder Interferometer.

Abstract: We have proposed a high sensitive photonic crystal fiber (PCF) strain sensor based on the Mach-Zehnder interferometer (MZI). The sensing head is formed by all-fiber in-line single mode-multimode-photonic-crystal-single mode fiber (SMPS) structure, using only the splicing method. Such a strain sensor exhibited a high sensitivity of -2.21 pm/μe within a large measurement range of up to 5000 μe and a large fringe visibility of up to 24 dB. Moreover, it was found that the strain sensitivity was weekly dependent of the length of PCF or MMF. In addition, the sensor exhibited the advantages of simplicity of fabrication, high sensitivity and larger fringe visibility.

Mach-Zehnder interferometric magnetic field sensor based on a photonic crystal fiber and magnetic fluid.

Abstract: A Mach–Zehnder interferometric magnetic field sensor based on a photonic crystal fiber (PCF) and magnetic fluid (MF) was designed and experimentally demonstrated. The sensing probe consists of a single-mode-(SM)-multimode-PCF-SM fiber structure through arc fusion splicing. It was then laser engrave notched with the femtosecond laser so that the PCF cladding was selectively infilled MF. A well-defined interference pattern was obtained on account of the tunable refractive index of the MF infilled PCF cladding. The transmission spectra of the proposed sensor under different magnetic field intensities have been measured and theoretically analyzed. The results show that the sensitivity of the proposed sensor can reach −0.13 dB/mT and 0.07334 nm/mT in the magnetic field intensity from 1 mT to 20 mT and 2 mT to 20 mT, respectively.

Femtosecond laser-inscribed fiber interface Mach-Zehnder interferometer for temperature-insensitive refractive index measurement.

Abstract: A new fiber interface Mach–Zehnder interferometer has been fabricated, to the best of our knowledge, in coreless fiber by femtosecond laser-inscription for temperature-insensitive refractive index measurement. A straight waveguide was inscribed along the central axis of the coreless fiber as the reference arm, and the other curved waveguide (interface waveguide) was then inscribed bending toward the cladding interface to obtain a strong evanescent field sensitive to ambient refractive index. This fiber interface Mach–Zehnder interferometer exhibits a high refractive index (RI) sensitivity of ∼3000 nm/RIU at an RI value of 1.432. Moreover, with the significant advantages of high mechanical strength and temperature independence, such a fiber Mach–Zehnder interferometer may find many potential applications in biochemical sensing.

Directional Bending Sensor Based on a Dual Side-Hole Fiber Mach–Zehnder Interferometer

Abstract: A new directional bending sensor based on a dual side-hole fiber (DSHF) that can detect both the direction and magnitude of bending in a self-temperature compensated manner is described and experimentally demonstrated. The sensor is based on an in-fiber Mach–Zehnder interferometer (MZI), where a DSHF segment was spliced between two standard single-mode fibers (SMFs) as input and output. The sensor has two orthogonal axes which are formed by both the asymmetry in the side-hole location in DSHF and an offset in the fusion splice between the SMF and DSHF. The visibility in the MZI output intensity and the spectral shifts of MZI fringes show separate responses to the bending curvature and direction, which is a key feature of the directional curvature sensor. An inscribed fiber Bragg grating in the DSHF measure allows the temperature to be measured independently. The sensor can provide salient advantages in its unique capability to precisely quantify the direction and magnitude of bending along with its reproducibility, compactness, and suitability for mass production, which makes it suitable for many practical bending sensing applications.

Design of All-Optical Universal Gates Using Plasmonics Mach-Zehnder Interferometer for WDM Applications

Abstract: All optical integrated circuits have great application in high-speed computing and information processing to overcome the limitation of conventional electronics. In this work, a novel design of all optical universal gates using optical Kerr-effect and optical bistability of a plasmonics-based Mach-Zehnder interferometer (MZI) has been proposed. A MZI is capable for switching of light which depends on the intensities of optical input signal. The study of device is carried out using finite-difference-time-domain (FDTD) method and verified using MATLAB simulation.

Compact assembly-free vector bend sensor based on all-in-fiber-core Mach-Zehnder interferometer.

Abstract: A novel low-cost, compact, assembly-free and sensitive optical fiber curvature sensor is presented. This device consists of an off-axis positive refractive index modified zone (PRIMZ), induced by direct femtosecond laser, written in single mode fiber (SMF) core. The PRIMZ transforms the original SMF section into a few-mode fiber (FMF). As a result, the whole fiber forms an assembly-free “SMF-FMF-SMF” sandwich Mach-Zehnder interferometer. When the device is bent, a direction dependent spectral shift of the interference pattern is produced. The sensitivity of the sensor is up to 2.53 and 2.24nm/m-1 for the 0° and 180° orientations in a wide bend range (from 0-4m-1). In addition, the device is immune to surrounding refractive index and has low temperature crosstalk, which make it very attractive for practical structural monitoring applications.

Live E. coli bacteria label-free sensing using a microcavity in-line Mach-Zehnder interferometer.

Abstract: The paper presents the first study to date on selective label-free biosensing with a microcavity in-line Mach-Zehnder interferometer induced in an optical fiber. The sensing structures were fabricated in a single-mode fiber by femtosecond laser micromachining. In contrast to other studies of this sensing scheme, where only the sensitivity to refractive index changes in the cavity was investigated, this research used chemical surface treatment of the sensor to ensure detection specificity. Immobilized MS2 bacteriophages were applied as recognition elements specifically targeting live E. coli C3000 bacteria. It is shown that the sensor allows for real-time monitoring of biological phenomena taking place on the surface of the microcavity. The developed biosensor exhibits ultrahigh refractive index sensitivity of 15,000 nm/RIU and is capable of detecting live E. coli bacteria concentrations as low as 100 colony forming units (CFU)/mL in liquid volume as low as picoliters.

Three Phase-Grating Moiré Neutron Interferometer for Large Interferometer Area Applications.

Abstract: We demonstrate a three phase-grating moire neutron interferometer in a highly intense neutron beam as a robust candidate for large area interferometry applications and for the characterization of materials. This novel far-field moire technique allows for broad wavelength acceptance and relaxed requirements related to fabrication and alignment, thus circumventing the main obstacles associated with perfect crystal neutron interferometry. We observed interference fringes with an interferometer length of 4 m and examined the effects of an aluminum 6061 alloy sample on the coherence of the system. Experiments to measure the autocorrelation length of samples and the universal gravitational constant are proposed and discussed.

Phase sensitivity of a Mach-Zehnder interferometer with single-intensity and difference-intensity detection

Abstract: Interferometry is a widely used technique for precision measurements in both classical and quantum contexts. One way to increase the precision of phase measurements, for example, in a Mach-Zehnder interferometer (MZI), is to use high-intensity lasers. In this paper we study the phase sensitivity of a MZI in two detection setups (difference intensity detection and single-mode intensity detection) and for three input scenarios (coherent, double coherent, and coherent plus squeezed vacuum). For the coherent and double coherent input, both detection setups can reach the quantum Cram\'er-Rao bound, although at different values of the optimal phase shift. The double coherent input scenario has the unique advantage of changing the optimal phase shift by varying the input power ratio.

Polarization-insensitive four-channel coarse wavelength-division (de)multiplexer based on Mach-Zehnder interferometers with bent directional couplers and polarization rotators.

Abstract: A polarization-insensitive four-channel coarse wavelength-division multiplexing (CWDM) (de)multiplexer based on Mach–Zehnder interferometers is proposed and demonstrated. By utilizing the bent directional couplers and the polarization rotators, the CWDM (de)multiplexer could work for both transverse electric and transverse magnetic polarizations. The measurement results of the fabricated devices show that the 1-dB bandwidth is ∼15 nm for dual polarizations, and the polarization dependent losses are <∼0.5 dB for all four channels.

Polarization-insensitive silicon nitride Mach-Zehnder lattice wavelength demultiplexers for CWDM in the O-band

Abstract: Polarization-insensitive silicon nitride (SiN) 4-channel wavelength (de)multiplexers based on Mach-Zehnder interferometer lattice filters for coarse wavelength division multiplexing (CWDM) in the O-band are demonstrated in a SiN-on-silicon photonic platform. For the best-performing device, the insertion loss was < 2.8 dB, the inter-channel crosstalk was < -11.5 dB for a polarization scrambled input, and the passband shift between the orthogonal polarizations was < 1.5 nm. Across the 200mm wafer, the die-averaged insertion loss and maximum crosstalk were 3.1 dB and -10.6 dB, respectively. The higher-than-expected crosstalk was due to dimensional variations. This work shows the potential of SiN photonic circuits for CWDM without polarization diversity.

Refractive index and strain sensor based on twin-core fiber with a novel T-shaped taper

Abstract: A compact in-fiber Mach–Zehnder interferometer (MZI) based on twin-core fiber (TCF) with a novel T-shaped taper is proposed and demonstrated. The taper was firstly fabricated by a short section of TCF, and then spliced with a section of cleaved single mode fiber (SMF). When the light transmit into the TCF, multiple modes will be excited and will propagate within the TCF. In experiment, the proposed device had a maximum interferometric extinction ratio about 17 dB. And the refractive index (RI), strain, and temperature response properties of the sensor have been investigated, which show a relatively high RI, strain sensitivity and low temperature cross sensitivity. Hence, the sensor can be a suitable candidate in the biochemical and physical sensing applications. And due to its easy and controllable fabrication, the novel drawing technology can be applied to more multicore optical fibers.

Switchable multi-wavelength laser based on a core-offset Mach-Zehnder interferometer with non-zero dispersion-shifted fiber

Abstract: In this paper, a switchable multi-wavelength erbium-doped fiber ring laser, based on a core-offset Mach-Zehnder interferometer (MZI) with non-zero dispersion shifted fiber (NZ-DSF), is proposed and experimentally demonstrated. Here, the core-offset MZI was implemented by fusion splicing a segment of a NZ-DSF between two single-mode fiber sections. In the proposed ring cavity design, the core-offset MZI is acting as a wavelength selective filter and it is optimized in order to achieve a single-mode suppression ratio (SMSR) of about of 56 dB. In addition, the laser is capable of emitting a single, double, or triple line, which can be switched from 1546 to 1564 nm by controlling its polarization states. Finally, this laser fiber offers a high output power stability at room temperature, compactness, robustness and low implementation cost.

Temperature sensor with enhanced sensitivity based on silicon Mach-Zehnder interferometer with waveguide group index engineering.

Abstract: We propose a highly-sensitive temperature sensor employing a Mach-Zehnder interferometer (MZI) based on silicon-on-insulator (SOI) platform The waveguide widths in the two MZI arms are tailored to have different temperature sensitivities but nearly the same group refractive indices A temperature sensor with an enhanced sensitivity of larger than 438pm/°C is experimentally demonstrated, which is over seven times larger than that of conventional silicon optical temperature sensor (about 60pm/°C for quasi-TM mode) Moreover, the sensor is easy to fabricate, only by a single mask, and no need of any polymer cladding, which makes it more robust, and can be used in lab-on-chip systems as a temperature monitor

Intensity-modulated directional torsion sensor based on in-line optical fiber Mach-Zehnder interferometer.

Abstract: In this Letter, we demonstrated an intensity-modulated directional torsion sensor based on an in-line Mach–Zehnder interferometer in single-mode fiber. A non-circular symmetric perturbation is created to excite non-circular symmetric cladding mode and then interference with the core mode at the second perturbation. An initial rotation angle is designed between two perturbations for the purpose of discriminating the torsion direction. Both experimental and theoretical results enforce that the spectral peak/dip turns to be the dip/peak when the fiber is twisted from the counter-clockwise to the clockwise direction. Benefiting from the reversal between peak and dip, an intensity-modulated directional torsion sensor is realized in the range from −50 rad/m to 50 rad/m with a sensitivity of 45.3%/(rad/cm).

Fiber in-line Mach-Zehnder interferometer based on a pair of short sections of waveguide.

Abstract: A fiber in-line Mach-Zehnder interferometer based on a pair of femtosecond laser inscribed short sections of waveguide is presented. One short waveguide directs part of the propagating light from the fiber core to the cladding-air interface, and experiences multiple total internal reflections before taking back to the fiber core by the other short waveguide. The device is robust in structure, can be fabricated in a fast way and with a flexible manner, and has the capability of ambient refractive index sensing, which makes it highly desirable for many “lab-in-fiber” applications.

High-sensitivity gas pressure sensor based on hollow-core photonic bandgap fiber Mach-Zehnder interferometer.

Abstract: We propose and experimentally demonstrate a highly sensitive gas pressure sensor based on a near-balanced Mach-Zehnder interferometer (MZI) and constructed by hollow-core photonic bandgap fiber (HC-PBF) in this paper. The MZI is simply constructed by fusion splicing two HC-PBFs, which are of slightly different lengths, between two 3-dB couplers. The two output ends of each coupler are approximately equal in length, to ensure that the optical path variations of the MZI only result from the differences in the lengths between the two HC-PBFs. To apply the MZI for gas pressure sensing, a femtosecond laser is employed to drill a micro-channel in one of the two HC-PBF arms. The experiment result shows that the proposed MZI based gas pressure sensor achieves an ultrahigh sensitivity, up to 2.39 nm/kPa, which is two orders of magnitude higher than that of the previously reported MZI-based gas pressure sensors. Additionally, the effects resulting from the absolute length and relative length of the two HC-PBFs on gas pressure sensing performance are also investigated experimentally and theoretically, respectively. The ultra-high sensitivity and ease of fabrication make this device suitable for gas pressure sensing in the field of industrial and environmental safety monitoring.

Relative humidity sensor based on small up-tapered photonic crystal fiber Mach–Zehnder interferometer

Abstract: In this paper, a new in-line mode Mach–Zehnder interferometer (MZI) based on photonic crystal fiber (PCF) coated with graphene quantum dots (GQDs) and polyvinyl alcohol (PVA) film for relative humidity (RH) sensing was designed The MZI was formed by splicing a section of PCF between two sections of single mode fiber (SMF) with two up-tapers The two up-tapers acted as mode splitter/combiner and were made by fusion tapering technique The Mach–Zehnder interferometer (MZI) incorporated inter modal interference between core mode and cladding modes of the PCF The refractive index (RI) and volume of GQDs-PVA film will decrease and expansion with the increase of RH, respectively By measuring the wavelength shift of the interference pattern, RH measurement could be achieved Before RH measurement, the external RI was tested experimentally to verify that the interference spectrum shifted to right with the increase of refractive index (RI), and the sensitivity was up to 3437 nm/RIU In addition, the RH sensing properties with the different thickness of GQDs-PVA film (248 μm, 372 μm, 445 μm, 596 μm, 742 μm, 817 μm) were also investigated experimentally, and the corresponding sensitivity were -00901 nm/%RH, −00797 nm/%RH, -00337 nm/%RH, 00586 nm/%RH, 00539 nm/%RH, 00313 nm/%RH, respectively The measurement result revealed that different film thickness had different sensitivity and spectrum movement direction Meanwhile, the sensor had the advantages of simple structure, small size, high sensitivity and low cost What’s more, the sensor also presents good stability and reversibility of the sensor

Optical Fiber Sensors Based on Fiber Ring Laser Demodulation Technology

Abstract: A review for optical fiber sensors based on fiber ring laser (FRL) demodulation technology is presented. The review focuses on the principles, main structures, and the sensing performances of different kinds of optical fiber sensors based on FRLs. First of all, the theory background of the sensors has been discussed. Secondly, four different types of sensors are described and compared, which includes Mach–Zehnder interferometer (MZI) typed sensors, Fabry–Perot interferometer (FPI) typed sensors, Sagnac typed sensors, and fiber Bragg grating (FBG) typed sensors. Typical studies and main properties of each type of sensors are presented. Thirdly, a comparison of different types of sensors are made. Finally, the existing problems and future research directions are pointed out and analyzed.

Highly Sensitive Strain Sensor Based on a Novel Mach-Zehnder Interferometer with TCF-PCF Structure.

Abstract: A highly sensitive strain sensor based on a novel fiber in line Mach-Zehnder interferometer (MZI) was demonstrated experimentally. The MZI was realized by splicing a section of photonic crystal fiber (PCF) with the same length of thin core fiber (TCF) between two single mode fibers (SMFs). The fringe visibility of MZI can reach as high as 20 dB in air. In particular, the strain sensitivity of −1.95 pm/μe was achieved within a range from 0 to 4000 μe. Furthermore, the strain properties of different length of MZI was investigated. It was found that the sensitivity was weekly dependent on the length of MZI. The strain sensitivities corresponding to the MZI with 35 mm PCF, 40 mm PCF and 45 mm PCF at 1550 nm band were −1.78 pm/μe, −1.73 pm/μe and −1.63 pm/μe, respectively. Additionally, the sensor has advantages of simple fabrication, compact size and high sensitivity as well as good fringe visibility.