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Schematic cross-section of SiN slot waveguide showing two SiN ridges with slot spacing in between them which are cladded by EO-polymer.
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Dimensional parameters are optimized comparing stoichiometric and Si-rich silicon nitride-based push-pull modulators using a slot waveguide structure, electro-optic polymer cladding, and in-plane ground-signal-ground electrode. An optical power confinement in slot spacing is examined for choosing the optimal device parameters for wavelength of 1550...
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... to prevent a proximity of effective indices between TE0 and TM0 mode, and to reduce a fabrication difficulty from high aspect ratio of waveguides. Thus, the thickness of 600nm and 550nm were achieved from the optimization for the stoichiometric SiN and Si-rich SiN, respectively. The cross-section designed device in this work is depicted in Fig. 1 where a stack of material layers (bottom-to-top) are included a silicon substrate, 3µm-thick buried oxide (BOX) and 2µm-thick EO-polymer. As presented in the schematic of the device cross-section, the SiN slot waveguide is placed on the top of BOX layer which is surrounded by EO-polymer. To ensure the maximum optical power confined in ...
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A monolithically integrated electronic-photonic Mach-Zehnder modulator is presented, incorporating electronic linear drivers along with photonic components. Electro-optical 3 dB & 6 dB bandwidths of 24 GHz and 34 GHz, respectively, were measured. The measurements are in good agreement with electronic-photonic post-layout simulation results and veri...
Citations
... As Si 3 N 4 is a dielectric and cannot facilitate intrinsic electro-optic activation [5], hybrid and heterogeneous integration are the only ways for the realization of high-speed modulators [11]. These techniques employ a variety of materials in combination with Si 3 N 4 , so as to achieve the modulation of light in the phase domain, such as silicon [21], graphene [22,23], ferroelectric lead zirconate titanate [24], electro-optic polymers [25], lithium niobate [26][27][28][29][30][31][32][33] and barium titanate oxide [34][35][36]. Out of those, Si 3 N 4 -LNOI is the prevalent solution in most recent publications with results demonstrating simulated bandwidth up to 1200 GHz [29], 95 GHz experimental 3dB-bandwidth (BW) for a 10 mm PS length and V π of 3.75 V [32]. ...
This paper presents a simulation-based analysis on the performance of plasmonic ferroelectric Mach-Zehnder in a ring (MZIR) versus symmetric Mach-Zehnder modulators (MZMs) on Si3N4 targeting O-band operation. The detailed investigation reveals the tradeoff between Au and Ag legacy noble metals providing lower modulator losses and CMOS compatible Cu featuring low cost. The numerical models also show that by opting for the MZIR layout there is a reduction in the Vπ x L product of 46% for Ag, 39% for Au and 30% for Cu versus MZMs. Time-domain simulations verify the successful generation of 112 Gbaud PAM-4 Signals from both MZIRs and MZMs for as low as 2 × 1.3 Vpp and 5µm long plasmonic phase shifters (PSs) with MZIRs providing a ΔQ signal improvement over MZMs of 2.9, 2.4, and 1.3 for Ag, Au, and Cu metals respectively. To the best of our knowledge, this is the first theoretical demonstration of such a low-loss, low-voltage, high-speed, and CMOS compatible plasmonic modulator on Si3N4, in the O-band.
... The lower efficiency is due to the fact that an increase in the gap size reduces the electric field and the fact that the gap size and PZT thickness influences the overlap between the microwave and optical fields. The factor 2 in the denominator accounts for the equal but opposite phase changes in the two arms of an MZM modulator [22,23]. ...
The increasing demand for high data rates and low power consumption puts silicon photonics at the edge of its capabilities. The heterogeneous integration of optical ferro-electric materials on silicon enhances the functionality of the silicon on insulator (SOI) platform to meet these demands. Lead zirconate titanate (PZT) thin films with a large Pockels coefficient and good optical quality can be directly integrated on SOI waveguides for fast electro-optic modulators. In this work, the relative permittivity and dielectric loss of PZT thin films deposited by chemical solution deposition on SOI substrates are analyzed at high frequencies. We extract $\varepsilon _r = 1650-2129$ ε r = 1650 − 2129 and tan (δ) = 0.170 − 0.209 for the PZT thin films in the frequency range 1-67GHz. We show the possibility of achieving bandwidths beyond 60GHz via a Mach-Zehnder modulator with V π = 7V, suitable for next generation data communication systems.
... yielding macroscopic EO activity values of several hundred pm/V, 6,7,10,20,48,128,134,175,[179][180][181][182][183][184][185][186][187][188][189][190][191] with exceptional materials yielding values more than 1000 pm/V. 7,9,16,17 Substantial progress has been made in improving thermal 6,9,48,52,128,192 and photochemical 129,185 stability via crosslinking, yielding materials that surpass Telcordia standards. ...
The growth of integrated photonics has driven the need for efficient, high-bandwidth electrical-to-optical (EO) signal conversion over a broad range of frequencies (MHz–THz), together with efficient, high bandwidth photodetection. Efficient signal conversion is needed for applications including fiber/wireless telecom, data centers, sensing/imaging, metrology/spectroscopy, autonomous vehicle platforms, etc., as well as cryogenic supercomputing/quantum computing. Diverse applications require the ability to function over a wide range of environmental conditions (e.g., temperatures from <4 to >400 K). Active photonic device footprints are being scaled toward nanoscopic dimensions for size compatibility with electronic elements. Nanophotonic devices increase optical and RF field confinement via small feature sizes, increasing field intensities by many orders of magnitude, enabling high-performance Pockels effect materials to be ultimately utilized to their maximum potential (e.g., in-device voltage-length performance ≤0.005 V mm). Organic materials have recently exhibited significant improvements in performance driven by theory-guided design, with realized macroscopic electro-optic activity (r33) exceeding 1000 pm/V at telecom wavelengths. Hybrid organic/semiconductor nanophotonic integration has propelled the development of new organic synthesis, processing, and design methodologies to capture this high performance and has improved understanding of the spatial distribution of the order of poled materials under confinement and the effects of metal/semiconductor-organic interfaces on device performance. Covalent coupling, whether from in situ crosslinking or sequential synthesis, also provides a thermally and photochemically stable alternative to thermoplastic EO polymers. The alternative processing techniques will reduce the attenuation of r33 values observed in silicon organic hybrid and plasmonic organic hybrid devices arising from chromophore-electrode electrostatic interactions and material conductance at poling temperatures. The focus of this perspective is on materials, with an emphasis on the need to consider the interrelationship between hybrid device architectures and materials.
... The insertion loss of our device is 5.74 dB, which include two grating coupling loss of 3.08 dB. Compared with other polymer/silicon nitride hybrid designs [41,28,43], our design shows the advantages of high bandwidth, high modulation efficiency and low insertion loss. The length of the active region of the structure is only 3 mm. ...
In this paper, a hybrid Mach-Zehnder optical modulator is proposed based on silicon nitride/organic polymer waveguides, which is expected to break through the performance bottleneck of the silicon-based optical modulator by exploiting the low-loss optical transmission property of silicon nitride waveguides and the excellent modulation performance of organic polymers. For reduction of the optical loss and ease of photonic packaging, perfectly vertical silicon nitride bidirectional grating couplers are utilized for both input/output optical coupling and power splitting/combining. Thus, a Mach-Zehnder interferometer can be constructed with a back-to-back configuration of such grating couplers. With grating apodization, the coupler can achieve a simulated coupling efficiency of 70%. To bridge the silicon nitride waveguides and the polymer waveguides, a longitudinal adiabatic mode-spot converter with a transmission efficiency of 99.2% was designed. In this paper, high-β donor-π bridge-accepter molecule YLD-124 combined with HD-BB-OH as the host polymer is utilized for a design example. The polymer waveguides with inverted ridge structure can be realized through the processes of silica cladding etching, spin coating or microfluidic trench filling of polymer. Following this design, we numerically demonstrate a hybrid silicon nitride-polymer Mach-Zehnder modulator with modulation efficiency of 1.57 Vcm and Electric-Optical bandwidth of 174 GHz. The total insertion loss is less than 5.74 dB, including two grating coupler losses of about 3.08 dB.
... Due to its insulating nature and centro-symmetric crystalline structure, optical modulation based on charge diffusion and respectively electro-optic effects cannot be applied directly when using SiNx 20 . However, optical phase modulation has been previously achieved by the integration of graphene 21,22 , LiNbO 3 23 , (EO) polymers 24,25 and BTO 26 on SiNx, but require complex fabrication schemes such as planarization and bonding and can suffer from degradation at high operating temperatures resulting in potential yield issues [27][28][29] . www.nature.com/scientificreports/ ...
A new family of phase change material based on antimony has recently been explored for applications in near-IR tunable photonics due to its wide bandgap, manifested as broadband transparency from visible to NIR wavelengths. Here, we characterize $$\hbox {Sb}_{2} \hbox {S}_{3}$$ Sb 2 S 3 optically and demonstrate the integration of this phase change material in a silicon nitride platform using a microring resonator that can be thermally tuned using the amorphous and crystalline states of the phase change material, achieving extinction ratios of up to 18 dB in the C-band. We extract the thermo-optic coefficient of the amorphous and crystalline states of the $$\hbox {Sb}_{2}\hbox {S}_{3}$$ Sb 2 S 3 to be 3.4 x $$10^{-4}\hbox {K}^{-1}$$ 10 - 4 K - 1 and 0.1 x 10 $$^{-4}\hbox {K}^{-1}$$ - 4 K - 1 , respectively. Additionally, we detail the first observation of bi-directional shifting for permanent trimming of a non-volatile switch using continuous wave (CW) laser exposure ( $$-5.9$$ - 5.9 to 5.1 dBm) with a modulation in effective refractive index ranging from +5.23 x $$10^{-5}$$ 10 - 5 to $$-1.20$$ - 1.20 x 10 $$^{-4}$$ - 4 . This work experimentally verifies optical phase modifications and permanent trimming of $$\hbox {Sb}_{2}\hbox {S}_{3}$$ Sb 2 S 3 , enabling potential applications such as optically controlled memories and weights for neuromorphic architecture and high density switch matrix using a multi-layer PECVD based photonic integrated circuit.
... It can be seen from the literature that EO-polymer modulators based on SiN waveguides (900 V·cm) have a higher Vπ · L compared with the Si based waveguide (0.008 V·cm) approach. To improve the performance of EO-polymer modulators based on SiN waveguides, the design of SiN slot waveguides and the space-charge effect of the silicon substrate have been studied and simulated in 2021 [94]. The result in this work shows that by controlling the polling process and the mode confinement, a minimum Vπ · L of 1.47 V·cm can be achieved. ...
In this review we present some of the recent advances in the field of silicon nitride photonic integrated circuits. The review focuses on the material deposition techniques currently available, illustrating the capabilities of each technique. The review then expands on the functionalisation of the platform to achieve nonlinear processing, optical modulation, nonvolatile optical memories and integration with III-V materials to obtain lasing or gain capabilities.
... Similarly, SiN has a wide transparency window from blue to near-infrared wavelengths; it also displays relatively small changes in its refractive index, which is inefficient because a long waveguide is required to obtain a sufficient change in the phase of light. However, its modulators operate across a wide range of wavelengths [31,32], based on EO or thermo-optic effects. ...
Chip-scale optical devices operated at wavelengths shorter than communication wavelengths, such as LiDAR for autonomous driving, bio-sensing, and quantum computation, have been developed in the field of photonics. In data processing involving optical devices, modulators are indispensable for the conversion of electronic signals into optical signals. However, existing modulators have a high half-wave voltage-length product (VπL) which is not sufficient at wavelengths below 1000 nm. Herein, we developed a significantly efficient optical modulator which has low VπL of 0.52 V·cm at λ = 640 nm using an electro-optic (EO) polymer, with a high glass transition temperature (Tg = 164 °C) and low optical absorption loss (2.6 dB/cm) at λ = 640 nm. This modulator is not only more efficient than any EO-polymer modulator reported thus far, but can also enable ultra-high-speed data communication and light manipulation for optical platforms operating in the ranges of visible and below 1000 nm infrared.
... The growing demand on reconfigurability of photonic-electronic integrated circuits [1,2] in neuromorphic computing [3,4], quantum computing [5][6][7][8] and microwave photonics [9][10][11] is drawing a particular attention towards active photonic devices compatible with CMOS circuitry requirements. Different physical mechanisms and materials have emerged as possible switching methods, e.g., liquid crystals [12], graphene [13], p-n junctions [14][15][16], non-linear materials [17], (EO) polymers [18,19] and electro-optic materials [20]. These methods enabling phase modulation are volatile and rely on a constant voltage being applied to sustain a particular phase shift. ...
In order to effectively control the state of an active integrated photonic component based on chalcogenide phase change materials, an efficient microheater operating at low voltage is required. Here, we report on the design of a graphene based microheater. The proposed system contains two separate graphene layers between which the phase change material cell of Ge2Sb2Te5 is placed. Three distinct switching possibilities are explored, using only the bottom layer, only the top layer or both graphene layers. A detailed investigation of the heater parameters is performed to optimise switching performance. A self-consistent multiphysics simulation of the crystallization process in the phase change material cell is conducted demonstrating the switching capabilities of the proposed design.
... The phase control scheme is commonly based on thermal-optical (TO) effects [8] or free carrier dispersion [9]. However, considering the low TO coefficient (about 2.45×10 −5 K −1 ) of Si 3 N 4 [10,11] and the high insertion loss caused by the latter, such methods usually require a complex design [12,13]. Si 3 N 4 platforms combined with lithium niobate (LN) [14], piezoelectric lead zirconate titanate (PZT) [15], and barium titanate (BTO) [16] have been demonstrated to have remarkable electro-optic properties, but they suffer from certain difficulties with the growth of thin films and a complex process [17]. ...
We demonstrate a low-power, compact micro-ring phase shifter based on hybrid integration with atomically thin two-dimensional layered materials, and experimentally establish a low-loss silicon nitride platform. Using a wet transfer method, a large-area few-layer MoS2 film is hybrid integrated with a micro-ring phase shifter, leading to a tuning efficiency of 5.8 pm V⁻¹ at a center wavelength of 1545.294 nm and a half-wave-voltage-length product as low as 0.09 V cm. Our device is designed to provide a hybrid-integration-based active phase modulation scheme for integrated optical communication networks with large-cross-section silicon nitride waveguides.
... The electric potential and electric field calculations are performed to clarify the influence of the claddings' resistivity during the poling process. As demonstrated in Fig. 3(a) and (c), an uneven potential distribution occurred owing to the space-charge effect of the silicon substrate and the discontinuous dielectric constant distribution [26]. From Fig. 3(b), the applied electric field in the EO polymer sandwiched by the TMOS side claddings can be estimated to be about 133.9 V/µm. ...
Efficient electro-optic (EO) modulation can be generated in the hybrid silicon modulator with EO polymer in the form of an in-plane coplanar waveguide and electrode structure. Strong confinement of the optical field in the hybrid structure is critical to performing efficient electric poling and modulation of the EO polymer. The waveguide consists of silica-based side claddings and an EO core for increasing the integral of the optical field and the overlap interaction between the optical field and the modulated electric field within the EO polymer. We discuss in detail the volume resistivity dependence of the efficiency of electric poling and modulation for various side-cladding materials. In a Mach-Zehnder interferometer modulator, the measured half-wave-voltage length product (VπL) is 1.9 V·cm at an optical communication wavelength of 1,550 nm under the TE optical mode operation. The high-speed signaling of the device is demonstrated by generating on-off-keying transmission at signal rates up to 52 Gbit/s with a Q factor of 6.1 at a drive voltage of 2.0 Vpp.
