Modeling of a 2x2 electro-optic Mach-Zehnder Interferometer optical switch with s-bend arms

Abstract

Abstract-In this paper, we present a 2×2 electro-optic switch based on a Mach-Zehnder interferometer (MZI) with tapered (s-bend) interferometric arms. All structures have been designed with a channel profile of titanium indiffused lithium niobate waveguides. The crosstalk analysis of the switch suggests that the crosstalk levels become worse (-12dB) when both interferometric arms of the structure are tapered. We have optimized the structure in order to reduce the overall switch losses (≤ 0.5dB) and to achieve the best possible extinction ratio (≥ 20dB).Mach-Zehnder structures have been used to design all optical switches in order to use them for high speed optical computers and communication networks [1][2][3][4]. All optical switches do not require electrical-optical inter conversion. Lithium niobate (LN) is a uniaxial crystal with two types of crystal orientation widely termed as zcut and x-cut. Lithium niobate based switches and modulators are compatible with large capacity and longhaul optical transmission systems operating above 40 Gbit/s [5]. Ti indiffused LN waveguides are suitable for switching applications because of their large electro-optic coefficient [6] that results in small transition time. In MZI structures, tapered interferometric arms have been used to compensate the phase error, generated by mismatching of the 3dB-couplers of the structure. Such structures, when connected to each other as interleavers can separate the odd and even wavelengths from a WDM signal consisting of a number of wavelengths and are suitable for designing wavelength selective modulators/switches. In these structures, the periodic response varies with respect to optical path length difference between the interferometric arms. The longer the length differences, the shorter the wavelength response oscillations [7]. This paper elaborates the design and analysis of MZI switches with tapered (s-bend shape) interferometric arms. The s-bends waveguide sections are designed using the adiabatic criterion [8] in order to suppress optical losses due to tapering arms. The performance of the switch is checked for low attenuation optical windows i.e. test wavelengths of 1.3μm and 1.55μm. In electro-optic switches [9], switching is achieved by changes in physical properties of materials due to modulating voltage. The observed phenomenon typically include changes in the index of refraction of materials, which are collectively referred as electro-optic effects. An electrical voltage changes the refractive index of the substrate which in turn manipulates the light through the appropriate waveguide path to the desired port [10]. A conventional 2×2 MZI switch shown in Fig. 1, consists of two interferometric arms of equal length connecting two -3dB couplers. The first coupler splits the input signal in two beams which, when passed through the interferometric arms, experience phase difference caused by voltage variations across electrodes. Finally, both beams with different phases are put together again into a single signal by the second -3dB ...

Performance Evaluation and Enhancement of 2×2 Ti: LiNbO3 Mach Zehnder Interferometer Switch at 1.3 μm and 1.55 μm

“…From the previous results, it is clear that extinction ratio and insertion loss are major drawbacks for titanium diffused lithium niobate switches under the previous parameters. Previous literature suggested that, these two drawbacks can be enhanced by controlling titanium strip thickness before diffusion [18]. This will be investigated in the following section.…”

“…In this section, we are going to investigate the effect of titanium strip thickness on for titanium diffused lithium niobate switch using a sample of suggested range from 0.048 µm to 0.062 µm in [18]. Table 5 represents the results of studying important design parameters under the samples of suggested Ti strip thickness range.…”

Implementation of 2-bit multiplier based on electro-optic effect in Mach–Zehnder interferometers

“…9) has been monitored. The power imbalance at the output splitter can be obtained using following definitions (Singh et al 2012).…”

“…Due to variation of the refractive index, the phase difference arises, and depending upon the phase, signal shifts from one waveguide to another waveguide. LiNbO 3 based MZI is characterized by the attractive features of compact size, thermal stability (Wooten et al 2000), re-configurability (Jin et al 2014), integration potential (Wooten et al 2000), low latency and low power consumption (Singh et al 2012;Kumar Kumar et al 2015b). Due to which many researchers have shown their keen interest and implemented various combinational and sequential circuits using MZIs (Kumar et al , 2014a(Kumar et al , b, 2015aRaghuwanshi et al 2013Raghuwanshi et al , 2014.…”

An optical synchronous up counter based on electro-optic effect of lithium niobate based Mach–Zehnder interferometers

“…To overcome this limitation, in this paper, authors have demonstrated the design for an optical counter based on electro-optic (EO) effect of LiNbO 3 based Mach-Zehnder interferometer (MZI). LiNbO 3 based MZI is characterized by the attractive features of compact size, thermal stability (Wooten et al 2000), re-configurability (Jin et al 2014), integration potential (Wooten et al 2000), low latency and low power consumption (Singh et al 2012;Kumar et al 2015b). Due to which many researchers have shown their keen interest and designed various combinational and sequential circuits using MZIs (Kumar et al , 2014a(Kumar et al , b, 2015aRaghuwanshi et al 2013Raghuwanshi et al , 2014.…”