Design Of Mach-Zehnder Interferometer Research Articles

Photonic crystal based interferometric design for label-free all-optical sensing applications.

Optical sensing devices has a great potential in both industrial and biomedical applications for the detection of biochemicals, toxic substances or hazardous gases thanks to their sustainability and high-selectivity characteristics. Among different kinds of optical sensors based on such as fibers, surface plasmons and resonators; photonic crystal (PC) based optical sensors enable the realization of more compact and highly efficient on-chip sensing platforms due to their intriguing dispersive relations. Interferometric devices based on PCs render possible the creation of biochemical sensors with high sensitivity since a slight change of sensor path length caused by the captured biochemicals could be detected at the output of the interferometer via the interferences of separated beams. In this study, a new type of Mach-Zehnder Interferometer (MZI) using low-symmetric Si PCs is proposed, which is compatible with available CMOS technology. Intended optical path difference between the two MZI channels is provided by the periodic alignments of symmetry-reduced PC unit cells in the MZI arms. Unlike the conventional symmetrical PC based MZIs, Fano resonances exist for the proposed MZI design, i.e. transmission dips and peaks appear in the output spectrum, and the location of dip and peak frequencies in transmission spectra can be efficiently controlled by utilizing interference phenomenon. Exploiting this effect, any refractive index change at the surrounding medium could be distinctly observed at the transmission spectra. In the view of such results, it is convenient to say that the proposed MZI configuration is suitable for efficient optical sensing of toxic gases as well as liquids. The designed all-dielectric MZI system is numerically investigated in both spectral and spatial domains to analyze its interferometric tunability: an optical sensitivity of about 300 nm/RIU is calculated for gaseous analytes whereas that sensitivity value is around 263.2 nm/RIU in the case of liquid analytes. Furthermore, high quality factor of Q > 45000 is obtained at Fano resonances with Figure-of-Merit (FoM) value of FoM ∼ 8950 RIU-1(7690 RIU-1) in the case of gas analytes (liquid analytes), which is the indication of enhanced optical sensing performance of the proposed MZI design. Considering all the above-mentioned advantages, the proposed interferometric configurations based on low-symmetric PCs could be utilized for efficient photonic sensor applications that require controllable output power or sensing of gaseous and liquid substances.

A compact 100 GHz femtojoule silicon-organic hybrid modulator based on a novel Mach–Zehnder interferometer design

In this paper, a high-speed, low-power and compact silicon-organic hybrid (SOH) modulator operating at the telecom wavelength is presented. The modulator is based on the mature and widespread silicon-on-insulator technology with a device layer of 220 nm. The proposed design utilizes a slot waveguide in a loop-terminated Mach–Zehnder interferometer (LT-MZI) configuration. The LT-MZI is twice as compact as the conventional MZI. Accordingly, the LT-MZI modulator exhibits a reduction in capacitance by a factor of two, which subsequently enhances the modulator speed and power consumption by a factor of two. An electro-optic polymer is used as it exhibits fast and strong electro-optic effects. Finite element and finite difference simulations show that for a driving voltage of only 0.5 V our modulator arms’ length is as low as 167 µm resulting in a Vπ × L product of only 0.084 V mm, 10.41 fF capacitance and up to 100 GHz speed with corresponding energy consumption of only 6.755 fJ bit−1. Results based on 3D finite difference time domain simulation show that our modulator can work over a large optical bandwidth of 60 nm with an extinction ratio (ER) greater than 23 dB and insertion loss (IL) less than 1.7 dB, reaching ER = 40 dB and IL = 1.15 dB at λ = 1.55 µm.

Fabrication-Tolerant CWDM (de)Multiplexer Based on Cascaded Mach–Zehnder Interferometers on Silicon-on-Insulator

We demonstrate a cascaded Mach–Zehnder interferometer (MZI) based coarse wavelength division multiplexing (CWDM) (de)multiplexer on silicon-on-insulator with its spectral responses well aligned to the defined wavelength grids and are highly tolerant to the manufacturing linewidth variability. This was achieved by optimizing the waveguide widths and lengths of two arms in every MZI. As-realized CWDM (de)multiplexer exhibits a spectral shift of 0.487 nm, an insertion loss of less than 2.1 dB, and a channel crosstalk of lower than −20 dB, while reference devices fabricated on the same chips suffer from serious spectral shift of 15.4 nm to the shorter wavelength and higher insertion loss/channel crosstalk. The proposed MZI design concept can be applied to all MZI-based photonic devices and related photonic integrated circuits, so this work validates a promising design path towards practical WDM applications on silicon-on-insulator.

Integrated photonics interferometric interrogator for a ring-resonator ultrasound sensor.

We present a compact integrated photonics interrogator for a ring-resonator (RR) ultrasound sensor, the so-called MediGator. The MediGator consists of a special light source and an InP Mach-Zehnder interferometer (MZI) with a 3 ×3 multi-mode interferometer. Miniaturization of the MZI to chip size enables high temperature stability and negligible signal drift. The light source has a -3 dB bandwidth of 1.5 nm, a power density of 9 dBm/nm and a tuning range of 5.7 nm, providing sufficient signal level and robust alignment for the RR sensor. The mathematical procedure of interrogation is presented, leading to the optimum MZI design. We measure the frequency response of the sensor using the MediGator, giving a resonance frequency of 0.995MHz. Further, high interrogation performance is demonstrated at the RR resonance frequency for an ultrasound pressure range of 1.47 - 442.4 Pa, which yields very good linearity between the pressure and the resulting modulation amplitude of the RR resonance wavelength. The measured signal time traces match well with calculated results. Linear fitting of the pressure data gives a sensor sensitivity of 77.2 fm/Pa. The MediGator provides a low detection limit, temperature robustness and a large measurement range for interrogating the RR ultrasound sensor.

Silicon Waveguide Optical Isolator with Directly Bonded Magneto-Optical Garnet

Silicon waveguide optical isolators were fabricated by direct bonding of magneto-optical (MO) garnet. The technique allowed efficient MO phase shift owing to the use of single-crystalline garnet and negligibly thin interlayer on the silicon core layer. A Mach–Zehnder interferometer (MZI) provided optical isolation utilizing the MO phase shift. High isolation, wide bandwidth, and temperature-insensitive operations had been demonstrated by tailoring the MZI design. Also, transverse electric (TE)–transverse magnetic (TM) mode converters were integrated to control operating polarization. In this paper, we reviewed these progresses on silicon waveguide optical isolators.

Design of on-chip hybrid plasmonic Mach-Zehnder interferometer for temperature and concentration detection of chemical solution

We report a compact lab-on-chip design of a Mach-Zehnder interferometer (MZI) incorporating a novel metal strip loaded horizontal slot hybrid plasmonic waveguide (HSHPW) in the sensing arm and a dielectric horizontal slot (DHS) waveguide in the reference arm. The HSHPW is optimized to confine a high ∼60% and ∼82% evanescent optical field in the low index dielectric slot and an active sensing region, respectively which enhance the device sensitivity with a comparative lower propagation loss than a typical plasmonic waveguide. We report here a single MZI configuration which not only exhibits an excellent temperature sensitivity of 243.9 pm/°C but also liquid concentration sensitivity of 437.3 nm/RIU for a 40 μm long HSHPW. To mitigate loss arising from each section such as butt coupling and plasmonic modal losses, the HSHPW has been optimized by incorporating an asymmetric power splitter which shows a considerable improvement in the fringe visibility and device insertion loss. Thus, the proposed single MZI design shows an excellent response to the temperature and liquid concentration sensing with a maximum total loss and extinction ratio of 2.56 dB and>25 dB, respectively. A much simpler CMOS friendly compact design is also found to have a great robustness to the fabrication tolerances.

Ultralow chirp photonic crystal fiber Mach-Zehnder interferometer.

A photonic crystal fiber Mach-Zehnder interferometer design was optimized to obtain high performance and ultralow chirp. Two long-period gratings were used to excite the cladding modes, and the rich structure of the cladding was tailored to obtain a slightly chirped free spectral range, as required by the Telecommunication Standardization Sector of the International Telecommunication Union (ITU-T) Norm G.694.1. Finally, a fabrication tolerance analysis was performed. The advantages of the proposed device are an ultralow chirp, high bandwidth, and fabrication robustness tolerance.

Numerical modeling of ultracompact folded photonic crystal waveguide Mach–Zehnder interferometer thermo-optic switch

We numerically studied an ultracompact folded-path photonic crystal waveguide Mach–Zehnder interferometer (MZI) thermo-optic switch based on a small-bend radius double 180° waveguide bend MZI arm. The design can at least double the active waveguide length and sensitivity while maintaining a small heater size compared to the conventional MZI design. From 3D finite difference time domain simulation, a refractive index increase of 0.019 in the 25 μm long heated arm that is induced by a temperature difference of 102 K produces a π phase shift in the output of the MZI.

Design of Mach-Zehnder interferometer and ring resonator for biochemical sensing

We proposed a compact design of an optical biochemical sensor based on the Mach-Zehnder interferometer (MZI), which was coupled by a ring resonator (RR) as a sensing tool. The sensor sensitivity has been determined by power difference at the output ports. The sensor enhancement has been optimized by numerically evaluating the geometrical parameters of the MZI and RR. A great sensor sensitivity depicted by Fano resonance characteristic has been demonstrated as a function of the round trip phase in the range of 4×10−4 − 4×10−4, which was changed by the presence of the sample solution in the sensing area. This optimum sensitivity has been obtained for the values of two coupling coefficients of the MZI κ 1 = κ 2 = 0.5/mm and the coupling coefficient between the MZI arm and RR κ R = 0.5/mm. Furthermore, a good profile of sensitivity exchange has been exhibited by inducing the direct current voltage to the coupling region of κ R . Finally, the output power transmission of the ring-coupled arm was depicted as a function of tunable κ R .

Performance improvement in Mach–Zehnder interferometer-based refractive index sensor using elliptical photonic nanowires

We propose a modified Mach–Zehnder interferometer design based on elliptical silica photonic nanowires. The use of the interferometer as an evanescent field-based refractive index (RI) sensor was numerically investigated. Single-mode operation, maintaining polarization and very high sensitivity, is achieved at short optical wavelengths by simply using elliptical nanowires. The proposed sensor is capable of determining the RI of benzene solutions with different concentrations in water and detecting a RI variation of the order of 10−6 RI units in only a 1-mm length sensitive area. Extremely high sensitivity of 4.63 rad/μm is achieved using an 800 nm elliptical silica nanowire diameter. The operating wavelengths (λ = 650 nm and 970 nm) were chosen to avoid high water absorption. The sensor is shown to be an alternative solution to small circular-nanowire-based sensor whose core size needs to be significantly reduced below 400 nm to achieve comparable performance.

Broadband Mach–Zehnder interferometer design using microstructured optical fibers for multi-channel DPSK demodulation

Microstructured optical fibers (MOFs) are typically all silica optical fibers with air holes. Tremendous interest in these fibers has been generated because of potential applications in optical communications, remote sensing, frequency metrology and optical coherence tomography. A feature of MOFs is that waveguide dispersion can be modified significantly by means of geometrical parameters, namely, the positions and sizes of the different holes. We propose here an innovative MOF design whose waveguide dispersion inversely matches the material dispersion of silica to obtain broadband zero group velocity dispersion from 1400 to 1650 nm. One application of this fiber is in the demodulation of differential phase shift keying (DPSK) signals. We propose a novel Mach–Zehnder interferometer design using a small section of zero-dispersion fiber providing a wavelength-independent time delay and address all practical considerations. The constant free spectral range of the interferometer would allow the demodulation of multiple evenly spaced wavelength-multiplexed DPSK-encoded channels in a telecommunication link instead of one demodulator per channel.

Highly sensitive differential phase-sensitive surface plasmon resonance biosensor based on the Mach–Zehnder configuration

A high-sensitivity surface plasmon resonance (SPR) biosensor based on the Mach-Zehnder interferometer design is presented. The novel feature of the new design is the use of a Wollaston prism through which the phase quantities of the p and s polarizations are interrogated simultaneously. Since SPR affects only the p polarization, the signal due to the s polarization can be used as the reference. Consequently, the differential phase between the two polarizations allows us to eliminate all common-path phase noise while keeping the phase change caused by the SPR effect. Experimental results obtained from glycerin-water mixtures indicate that the sensitivity limit of our scheme is 5.5 x 10(-8) refractive-index units per 0.01 degrees phase change. To our knowledge, this is a significant improvement over previously obtained results when gold was used as the sensor surface. Such an improvement in the sensitivity limit should allow SPR biosensors to become a possible replacement for conventional biosensing techniques based on fluorescence. Monitoring of the bovine serum albumin (BSA) binding reaction with BSA antibodies is also demonstrated.

All-fiber dynamic gain slope compensator

An all-fiber dynamic gain slope compensator is demonstrated, based on Mach–Zehnder interferometer design. Low voltage and electrical power are used to tune the attenuation slope via thermo-optic effect. A constant average insertion loss mode is demonstrated.

New Development of Mach-Zehnder Interferometer for Laser Frequency Selection and Tuning

A new design of Mach-Zehnder interferometer (MZI), efficiently suitable for stable single mode operation and laser cavity frequency tuning, is developed. This development eliminates the using of any additional etalons. The design is compact, broadband, low loss, easily adjustable in the laser cavity, and has a free spectral range (FSR) of 42·5 GHz. This design permits different uses in the field of laser spectroscopy and laser applications.