Optimization of 2×2 MZI electro-optic switch and its application as logic gate

In this paper, the SWAP gate is realized using the electro-optic (EO) phenomenon in the Mach-Zehnder Interferometer (MZI). In the structuring of the SWAP gate, two MZI is being used, and output is obtained from the bar port of both MZI. The SWAP gate output is obtained from MATLAB by using the mathematical description of MZI. The proposed layout of the SWAP gate is designed using titanium diffused lithium niobate (Ti:LiNb03) waveguide and simulated using the beam propagation method (BPM) at 1.33 μm wavelength.

Development of modern optical fiber networks puts an increasing demand on the optical hardware. All-optical signal processing components enable the highest switching rates and allow all-optical regeneration of pulse streams without converting the optical signal into electrical current. The subject of our research is self-switching in a Mach-Zehnder interferometer (MZI) and its applications in optical telecommunication networks. In this device, light injected in one of the input ports is unequally distributed over the two interferometer arms. Due to the intensity dependent refractive index in the interferometer arms, there can be a nonlinear phase shift induced between the optical signals of unequal intensities. The two signals therefore interfere destructively or constructively depending on the input power: in this way we obtain nonlinear self-switching. Two mechanisms of nonlinear phase shifting were considered: active, based on semiconductor optical amplifiers (SOAs), and passive, based on quantum dots (QDs). Interferometers of two types were developed: 2-to-2 (two input ports and two output ports) and 2-to-1 (two input ports and one output port). The 2-to-2 SOA-MZIs based on self-switching have been investigated for two applications. One of them is the pattern effect compensator. If SOAs are employed for all-optical signal amplification, e.g. in optical access networks, an unwanted pulse distortion (known also as the pattern effect) takes place, as a result of the SOA gain saturation. Our component allows pattern-free amplification of the optical signals at bitrates up to 20 Gb/s. At 10 Gb/s it shows an extended input power range (up to 7 dB improvement) and comparable gain, which makes it suitable to be used as an optical amplifier. Another application of the 2-to-2 SOA-MZI is a 2R-regenerator. Optical amplifiers used in long distance optical links add noise to the optical signal, causing signal degradation. The signal can be regenerated by passing it through an optical gate with a nonlinear transfer function. The 2-to-2 SOA-MZI has such a nonlinear transfer function. The regeneration capabilities were demonstrated at 2.5 Gb/s by an improvement of the receiver sensitivity of about 2.5 dB. The dynamic characterization of the chips was carried out in a close cooperation with the research group COM at the Technical University of Denmark within the ePIXnet "network of excellence". The 2-to-1 MZI based on self-switching can be used as a low-loss optical combiner. An essential function in optical fiber networks is the combining of optical signals. A serious disadvantage of the conventional type of combiners used in the networks is that they let only half of the power (3 dB) through. In order to compensate for this loss, passive optical combiners are often used in combination with an in-line SOA. The first realization of the low-loss optical combiner uses SOAs as active phase shifters. Such an active low-loss combiner shows an improvement of transmission of over 2 dB compared to a conventional combiner with an in-line SOA. It is therefore expected that the output optical signal-to-noise ratio of the self-switching SOA-MZI is more than 2 dB better than that of a conventional combiner with an in-line SOA. While for the pattern effect compensator and the 2R-regenerator SOAs are used not only for inducing the nonlinear phase shift, but also for sufficient amplification, for the low-loss optical combiner the preferred nonlinear effects should be passive: combination of the signal is a passive function. Therefore, the second realization is based on a novel material, quantum dots. QDs provide improved all-optical nonlinearities resulting in a very small switching energy and large refractive index changes. Such a passive 2-to-1 QD-MZI based on self-switching showed an improvement up to 1.7 dB with respect to a conventional combiner. These improvements have a huge effect on e.g. the power budget in passive optical networks, where a large number of splitting stages are required. The Mach-Zehnder interferometers were realized in the InP/InGaAsP semiconductor material system, which is perfectly suitable for the integration of the photonic integrated circuits for the telecommunication applications. In order to realize both active components (such as e.g. SOAs) and passive components (such as e.g. waveguides, couplers), an active-passive integration technique was applied. This integration was realized in a close cooperation between JDS Uniphase Eindhoven and the COBRA Research Institute. It employs a three-step metal-organic vapor-phase epitaxy regrowth process. The quantum dot material was grown within the COBRA Research Institute. Our MZIs use a ridge waveguide design, for which a reactive ion etching process was developed in the COBRA cleanroom. As a result of photonic integration our integrated Mach-Zehnder interferometers have very small dimensions: less than a square millimeter.

We present the design of a 2×2 photonic switch operating at 1.55-μm wavelength using electro-optic (EO) polymer waveguides. A Mach-Zehnder interferometer (MZI) is used to implement the proposed switch in which two identical 2×2 multimode interference (MMI) couplers are connected by two identical parallel single mode waveguides (two MZI arms). These two single-mode waveguides with electrodes allow modulating the phase difference between the two MZI arms based on the EO effect. In the proposed switch, the EO polymer, IPC-E/polysulfone, is used for the core layer of optical waveguides. UV15 and NOA61 are employed for the lower and upper cladding layers, respectively. The singlemode waveguide structure and 2×2 MMI coupler have been designed and analyzed for the EO switch. Device performance has been simulated using the beam propagation method. It is found that the switch performance is most sensitive to the MMI width and less sensitive to the MMI length. Optimized structure has been obtained for the 2×2 polymeric EO switch, which has a crosstalk level better than -25 dB and insertion loss lower than -1.8 dB. This performance makes the switch a potential candidate for practical use in photonic systems.

Mach-Zehnder Interferometer (MZI) is used to measure the phase shift (Δφ) between two light beams related to relative length difference (ΔL) of MZI's two arms. The phase shift of the interferometer output is represented by output Free Spectral Range (FSR). Thus the FSR can be configured by setting its length difference of the two arms, to vary the phase shift. In this paper, the FSR of two couplers MZI are compared with three couplers MZI with two configurations based on the two couplers MZI's length difference. Length difference of the two couplers MZI is utilized for both of the length differences for the first configuration of three couplers MZI. As for the second configuration, each of the three couplers MZI length differences is half of the two couplers MZI length difference. The two couplers MZI are designed to have FSR at 10 nm, which can be obtained by using 0.166 mm as the length difference. 3 dB couplers are used for all of the configurations. Only one input port is utilized and the outputs are simulated in a normalized graph form. The MZIs simulation shows that the FSR of three couplers MZI first configuration is 5 nm, half of the FSR of two couplers MZI, while the FSR of three couplers MZI second configuration is 10 nm, the same as the FSR of two couplers MZI.

We present a multifunction optical filter that operate as: 1) symmetric interleaver (SI); 2) asymmetric interleaver (AI); 3) dual-wavelength, channel passing add-drop filter (ADF); and 4) dual-wavelength, channel dropping ADF. The new filter is a pair of direct-coupled all-pass-filter (APF) and cross-coupled APF positioned in each of the two arms of a Mach-Zehnder interferometer (MZI). Depending on the MZI's path length difference and the values of the coupler's coefficients, these four functions are demonstrated. The interleaver has a superior flat-top profile, low ripple value ( -0.095 dB for SI, -0.075 dB for AI), and high extinction ratio . The effect on waveguide losses on flat-top, ripple, slope, and SNR are also investigated.

High sensitivity represents one of the main goals that sensing devices need to satisfy for their applications. This work presents to the best of our knowledge the first integrated Mach-Zehnder interferometer (MZI) embedded in soda-lime glass with comparable sensitivity to silicon-on-insulator (SOI) devices. We manufactured the MZIs by the femtosecond direct laser writing (FDLW) technique and characterized them with temperature. Four buried MZIs were manufactured by slightly increasing the optical path due to separation between the arms of the interferometer (Δ s). We achieved a fringe shift of ∼8n m for an increase of 0.18µm. We have characterized one of these devices with temperature from 30°C to 70°C obtaining a sensitivity of ∼28p m/ ∘ C. We improved the sensitivity of the device to ∼54p m/ ∘ C due to the advantage of the unique three-dimensional (3D) capabilities that FDLW provides, overcoming the characteristically low thermo-optic coefficient of soda-lime glass just by rotating the MZI structure 11°.

An overview of the advanced Indium Phosphide (InP) Electro-Optic Mach-Zehnder (MZ) Modulator technology which enables small form factor pluggable transceivers for coherent transmission is presented here. A highly efficient IQ-Modulator with a low insertion loss (IL), low Vπ, high extinction ratio and high electro-optic bandwidth is demonstrated. The modulator described here is very well suited for pluggable 100G/200G coherent transceivers with stringent electrical power consumption requirements. Additional functions already implemented on the mature InP photonic integration platform are expected to add further functionality to the InP IQ Modulator and finally result in a monolithic InP coherent transmitter.

A Mach–Zehnder interferometer (MZI) electro-optic (E-O) switch based on a guest–host material DR1/PC was designed and fabricated. The optical properties and long-term stability of the material were studied. By optimizing the concentration of DR1, the DR1/PC material exhibited an E-O coefficient of 12.8 pm/V at 1310 nm. The characteristic parameters of the waveguide were calculated, and the fabrication process was strictly controlled. The MZI switch on-off time was found to be about 50 ns. The extinction ratio was measured to be about 13.4 dB. At room temperature, the switch could keep operating for at least 150 days.

We propose and fabricate an ultrafast and high extinction ratio 1×4 optical switch based on a cascade, dual-output Mach–Zehnder interferometer (MZI) on the lithium niobate platform. The optical switch consists of cascaded, identical, dual-output MZI structures, and each of them includes a Y-branch waveguide, two parallel interference arms (electrode action area), and a 3 dB directional coupler. Four output optical paths can be switched through three groups of electrode hierarchical modulation. The test results of the fabricated device show that the insertion loss of each port is less than 7.1 dB and that the maximum extinction ratio is higher than 39.3 dB. The optical switch can achieve a high extinction ratio greater than 20 dB within the 50 nm wavelength range. The measured half-wave voltage is less than 4.13 V, and the minimum switching rise and fall times reach 125 ps and 250 ps, respectively. This result shows that the proposed and fabricated 1×4 integrated optical switch on a lithium niobate platform has the advantages of a fast response rate, high extinction ratio, and low switching voltage.

Recently optoelectronics devices have been prominent in the research field. The electro-absorption modulator has been used to modulate the strength of a laser beam using an electrical voltage (intensity modulators) depending on the Franz-Keldysh effect. This paper presents a positive-intrinsic-negative diode (PIN) structure to model the electro-absorption modulator using the finite element method (FEM). This structure is distinguished by its has small footprint is only 10 µm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> has been getting. The proposed structure's dimension is carefully calculated to suit the 1.55 µm wavelength. The proposed modulator consists of germanium as a core and silicon as a substrate with an active length is 15 µm to be compatible with chip optical interconnects. The f-3db bandwidth is high equal to 61.5 GHz, despite the small footprint with low insertion loss and high extinction ratio at low reverse voltage bias.

Hazelnut proteins detection in cookies using an immersible label-free photonic chip sensor

Mach-Zehnder interferometers have previously been demonstrated for electromagneticfield sensing.1 Linear modulation is achieved passively, without use of a DC voltage bias, by means of a difference in interferometer arm lengths, corresponding to an intrinsic phase bias ϕo = 90°. In practical devices imprecise fabrication results in deviations from the desired 90° angle, because of differences in phase velocity along the two arms.2 Methods to tune optical devices by phase-velocity adjustment have been reported3,4 but are relatively slow, involving lithography of an oxide cladding layer and of limited accuracy. Tuning of an annealed proton-exchanged LiNbO3 directional coupler by using a CO2 laser beam focused to ~50 μm spot size was recently reported.5 Here we report a fast, accurate method for tuning interferometers to 90° after fabrication. Tuning was performed on a packaged modulator, with the phase bias measured in situ during tuning and correction.

A picosecond pulse multi-wavelength erbium-doped fiber ring laser based on an optically switchable/tunable Mach-Zehnder interferometer (MZI) filter is proposed and experimentally demonstrated. The MZI configuration is constructed with two 3 dB couplers and two short pieces of endlessly single-mode photonic crystal fiber with different lengths in each arm. The combination of the MZI and a polarization controller (PC) acts as a selective comb filter and a mode-locking device. By adjusting the pump power or the first PC (PC1) state, the laser can emit up to 10 channels with a 20 nm tuning range (1530 to 1550 nm). Furthermore, by changing the PC1 condition, stable picosecond mode-locking generation with a repetition rate of 13.5 MHz is realized. To achieve wavelength spacing tunable multiple-channel laser emissions, the MZI is configured by incorporating a second PC (PC2) in one arm of the conventional MZI. Four channels of picosecond mode-locking pulses with a repetition rate of 11.6 MHz in the range of 1530-1550 nm are realized by carefully controlling the pump power and/or PC2 state. With the manipulation of intracavity birefringence through PCs with comb filtering via MZI, the proposed structure may be a potential tool in various photonics applications.

A highly sensitive temperature sensor is proposed and demonstrated based on a UV-curable polymer-infiltrated Mach-Zehnder interferometer (MZI) created in a graded index fiber (GIF). The device was constructed by splicing a half-pitch GIF between two single-mode fibers and creating an inner air cavity in one lateral side of the GIF core by means of femtosecond laser micromachining. The air cavity and the residual GIF core functioned as two interference arms of the MZI. Moreover, the GIF was used as a miniature in-fiber collimator to reduce insertion loss of the air cavity. Experimental results show such an MZI device has a high refractive index (RI) sensitivity of 24611.54nm/RIU (RI=1.545-1.565). Subsequently, thermo-sensitive polymer liquid was infiltrated into the air cavity, then cured with UV illumination, and annealed at 50°C for 12h. The infiltrated MZI exhibits a high temperature sensitivity of -13.27 nm/°C. In addition, this MZI also has excellent thermal stability and repeatability, compact structure, low insertion loss, and high fringe visibility. As such, the proposed MZI could be developed for high-accuracy temperature measurements in many areas such as biomedical or oceanographic applications.

2R regeneration is proposed with an integrated Mach-Zehnder interferometer containing a monomodal semiconductor optical amplifier (SOA) and an SOA with a 1 /spl times/ 1 multimode interference (MMI) coupler-SOA in the arms. Simulations and measurement of the static transfer function show a digital shape with a high extinction ratio improvement.