Output Of Mach-Zehnder Interferometer Research Articles

Optical fibre based quench detection in HTS applications using machine learning classifiers

A Mach-Zehnder Interferometer (MZI) based optical fibre sensing technique, developed and patented by EPFL, is an efficient and economical way to detect hotspots in High Temperature Superconductor (HTS) applications. Due to the MZI sensitivity being a composite of strain sensitive and temperature sensitive contributions, the MZI gives an instantaneous response to a quench (within 10 ms), because of the quick strain transfer to the optical fibre. However, the MZI output signal can also manifest the environmental noise caused by mechanical vibrations, bubbling in the cryostat and temperature variations, along with the response to the quench. This presents the problems of false alarms and indiscernible response to a quench. Discrete wavelet transform (DWT) has been proven to be a useful tool for feature extraction in different fields requiring signal categorization and hence holds the potential to enable quench recognition in the MZI output. This paper proposes an effective approach of performing DWT based feature extraction on experimental data and subsequently using the extracted features for the MZI response classification using two machine learning based classification techniques: k-nearest neighbours (KNN) and Artificial Neural Network (ANN). For this manuscript, experiments were performed using MZI for quench detection in an HTS tape. Feature extraction was then implemented on these experimental measurements using discrete wavelet coefficients extracted at different decomposition levels from the MZI output; these features were then used to train the KNN and ANN models for identifying quench in the MZI signal. This method could be a valuable supplement to the MZI technique by enabling the development of a real time application that can process the MZI output data as well as eliminate the occurrences of false alarms; thereby facilitating reliable quench detection. With this development, the MZI technique would become an even more attractive solution for the health monitoring of HTS applications.

Temperatures effects on cascaded Mach-Zehnder interferometer structures

To increase bandwidth and number of channels per fiber for more than one wavelength in the same fiber the dense wavelength division multiplexing (DWDM) technology has been utilized. One of the devices that are important in DWDM is an optical interleaver. This paper discussed the effects of temperatures in the DWDM interleaver by using the Mach-Zehnder interferometer (MZI) structures which is arranged in two-stage cascaded MZI and the three-stage cascaded MZI geometries. The main consequences of increase temperature inside the fiber optics are the change of effective refractive index in the material of silica fiber due to the thermo-optics effects. In our analysis we have used the transfer matrix method to investigate the wavelength dependence of output power to the temperatures changes that varies from 30oC to 430ºC. In the calculation we have used the C-Band range wavelength which is around 1530 to 1565 nm. It has been shown that the change of temperatures may shift the wavelength inside the MZI output power in linear manners. These effects may be used to tune wavelength transmission inside the MZI structures to suit the ITU-T defined grid.

LiFi up-downlink conversion node model generated by inline successive optical pumping

An on-chip-scale, up-down link conversion circuit for electro-optic signals to use in a light fidelity network application is proposed. A system consisting of a loop microring resonator (known as a Panda-ring resonator), is coupled inline to the input of a Mach–Zehnder interferometer (MZI). When the light from that source is input into the system, a fraction of the power is coupled inline through successive pumping and then circulated within the system. By using the most appropriate device parameters, the whispering gallery mode (WGM) of the light, with the inline successive pumping condition, is generated at the resonance condition. The transmitted signals are a combination of the comb and WGM signals and are obtained at the MZI output. The simulation results obtained have shown that a maximum power of 300 mW is achieved from the device. A comb signal, over the spectral band from 1.350–1.750 µm is obtained, with the center wavelength at 1.55 µm. The results show an up-downlink switching speed of is ~ 20 fs is also obtained.

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

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.

All-Optical Modulation with a Surface Plasmon Mach–Zehnder Interferometer

We use two parallel nano-slits in a silver film to form a surface plasmon Mach–Zehnder interferometer (MZI), based on the interference of two surface plasmon waves propagating along the two surfaces of the silver film. Coating the silver film with a photoinduced birefringence polymer film, we achieve optical modulation of the MZI output by changing the refractive index of the polymer film with a pump beam. An on/off ratio of 2.7 is obtained for a probe wavelength of 865 nm.

Fano resonance-based electrically reconfigurable add-drop filters in silicon microring resonator-coupled Mach-Zehnder interferometers

We report a Fano resonance-based electrically reconfigurable add-drop filter using a microring resonator-coupled Mach-Zehnder interferometer (MZI) on a silicon substrate. Our experiments reveal a pair of complementary Fano resonance line shapes that can be electrically tuned and output coupled from the MZI output ports. A near symmetrical resonance peak can be flipped to a near symmetrical resonance dip by applying a forward-bias voltage of less than 1V across a laterally integrated p-i-n diode in the MZI non-resonator-coupled arm. Our scattering-matrix-based modeling shows good agreement with the experiments and indicates ways to enhance the resonance routing functionality. Our work demonstrates the feasibility of an integrated reconfigurable add-drop filter with actively interchangeable throughput and drop ports.

UV Photosensitivity in a<tex>$hboxTa_2 hboxO_5$</tex>Rib Waveguide Mach–Zehnder Interferometer

The ultraviolet (UV) photosensitivity of Ta/sub 2/O/sub 5/ measured in a rib waveguide Mach-Zehnder interferometer (MZI) is reported. With a cumulative fluence of 72 J/cm/sup 2/ at a wavelength of 248 nm incident upon one arm through a 3-mm-long window, the MZI exhibits a phase shift of 8/spl pi/ radians at wavelength /spl lambda/=1.55 /spl mu/m, corresponding to a saturated refractive index change of 2.1/spl times/10/sup -3/. Real time measurements of the MZI output during exposure are given and the UV-induced refractive index change is found to be negative.