Electro-optic Waveguide Modulators Research Articles

Ultra-fast perovskite electro-optic modulator and multi-band transmission up to 300 Gbit s−1

The gap between the performance of optoelectronic components and the demands of fiber-optic communications has narrowed significantly in recent decades. Yet, the expansion of data communications traffic remains substantial, with fiber-link speeds increases anticipated in the near future. Here, we demonstrate an ultra-high-speed electro-optic waveguide modulator constructed using a thin film of lanthanum-modified lead zirconate titanate with a ferroelectric phase exhibiting a strong Pockels effect. The modulator has a wide optical window; thus, the modulation was demonstrated for 1550 and 1310 nm wavelengths. This device showed electro-optical intensity signaling with line rates of 172 Gbit s−1, in conjunction with on–off keying modulation; this performance could be increased to 304 Gbit s−1 using four-level pulse modulation. The signaling performance of this modulator was found to be robust, with stable performance at temperatures as high as 100 °C. This technology is expected to have applications in a wide range of classical optoelectronic devices and in quantum science and technology.

Synthesis, electro‐optic properties, and performance of novel fluorinated polyurethaneimide

AbstractUrethane imide anhydride oligomers with terminal groups as anhydride groups were designed and synthesized using second‐order nonlinear optical chromophore molecule, bisphenol AF‐type diethylidene dianhydride, and toluene diisocyanate as monomers. Polyurethaneimide (PUI) second‐order nonlinear optical polymers with the structure of imide and amino ester chain segments were then synthesized by the polycondensation reaction between urethane imide anhydride oligomers and aromatic diamine monomers. The glass transition temperature (Tg) of PUI reached 186°C, and the 5% heat‐loss decomposition temperature was 320°C. The corona‐polarized PUI had an electro‐optic (EO) coefficient (γ33) of 82 pm/V tested by the reflection method. The loss of light transmission of the polymer waveguide prepared with PUI as electro‐optical material was 1.13 dB/cm at 1550 nm. Mach–Zehnder type polymer waveguide electro‐optical modulators have been prepared based on the properties of the electro‐optic material PUI. The fabricated polymer EO modulators had favorable electro‐optic modulation response performance for low‐frequency electrical signals. The good modulation characteristics of the manufactured electro‐optical modulators proved that the synthesized PUI was a waveguide polymer material with good comprehensive performance.Highlights Electro‐optic fluorinated polyurethaneimide was synthesized. Polyurethaneimide as core material, polymer waveguide EO modulators were fabricated. The prepared modulators had good electro‐optic modulation performance.

Frequency-multiplexed on-demand storage in five modes of atomic frequency comb through simultaneous application of control pulses.

In quantum communication with quantum repeaters, multiplexed quantum memory is expected to enhance communication rates. When using an atomic frequency comb (AFC) for on-demand storage, the frequency mode number is often limited by the optical power of the control pulses. Here, using a space-coupled waveguide electro-optic modulator, we increased the output power, allowing us to apply control pulses to multiple modes simultaneously. Further, through enhancement of an experimental setup that increases power density, we increased the number of modes. Consequently, we pioneered, to the best of our knowledge, on-demand storage using five modes of AFC. This technology is a significant achievement toward frequency-multiplexed on-demand quantum memory.

Synthesis and Characterization of Electro-Optic Polyurethaneimide-Polyimide Copolymers

Polyurethaneimide prepolymer was synthesized using the synthesized chromophore C containing tricyanofuran, hexafluorodianhydride and phenyl diisocyanate as monomers. Polyimide prepolymers were synthesized using fluorinated aromatic diether dianhydride and fluorinated aromatic diamine as monomers. Polyurethaneimide-polyimide (PUI-FPI) copolymers were then synthesized by a polycondensation reaction of the polyimide and polyurethaneimide prepolymers. The electro-optic (EO) PUI-FPI copolymers had a special segment structure and concentrate the advantages of polyurethaneimide and polyimide. The copolymers exhibited good film-forming properties, high glass transition temperature (Tg =196 °C), and high thermal stability (Td up to 358 °C). The copolymers possessed a high EO coefficient (γ33 =72 pm/V) at the 1550 nm wavelength, good long-term electro-poled orientation stability, and low optical propagation loss (1.2–1.4 dB/cm) at 1550 nm. Mach-Zehnder interferometric electro-optic modulators were designed and fabricated using the synthesized copolymer as the waveguide material. The prepared polymer optical waveguide EO modulators showed a good low-frequency electro-optic modulation response. The results showed that the synthesized polyurethaneimide-polyimide copolymers meeted the performance requirements for the preparation of polymeric optical waveguide devices and were suitable as polymeric electro-optic waveguide materials.

An improved device and demodulation method for fiber-optic distributed acoustic sensor based on homodyne detection

An improved fiber-optic distributed acoustic sensor (DAS) using a LiNbO3 straight through waveguide electro-optic phase modulator and a novel phase demodulation method based on homodyne detection is proposed in this paper. The principles of the phase-sensitive optical time domain reflectometer (Φ-OTDR) system and the multi-point disturbances phase demodulation algorithm are described in detail. The system structure can solve the problems of large size, difficult integration, low modulation frequency and unstable performance of piezoelectric transducer (PZT), which exists in the traditional homodyne detection system based on Michelson interferometer (MI). Experiments show that it can realize the location and identification of multi-point disturbances, and the acoustic signal can be demodulated accurately. The detectable acoustic frequency depends no longer on the phase modulation frequency. The signal-to-noise ratio (SNR) is above 20 dB, the noise level (NL) is less than 4 × 10−3 rad/√Hz, and the spatial resolution is about 10 m at 5 km sensing fiber. Compared with the heterodyne detection system and traditional homodyne detection system, the system has the advantages of lower cost, higher detection frequency, more stable performance and easier to integrate, which can be applied in some specific fields, such as oil and gas exploration, pipeline detection, border security and so on.

Fast polarization control for optical frequency combs.

Polarization of an optical frequency comb is electrically controlled using a waveguide electro-optic phase modulator (WG-EOM). Owing to the low operation voltage and wide electric bandwidth of the WG-EOM, fast polarization control is possible. It is found that birefringence of the WG-EOM and polarization-maintaining optical fibers causes polarization-dependent pulse separation, which makes polarization control of the optical frequency comb impossible. Therefore, compensation of the birefringence is required for polarization control. In the experiment, a delay line in free space is used for birefringence compensation, and pulse-to-pulse polarization control of an optical frequency comb (with a repetition rate of 100 MHz) is demonstrated.

All-dielectric graphene-induced waveguide electro-optic modulators with offset nanowires

All-dielectric waveguide modulators nowadays are critical for on-chip photonic circuit’s integration. We propose and theoretically demonstrate a graphene-based all-dielectric waveguide modulator with offset nanowires. The displacement between the nanowires causes the electric field parallel to the graphene to increase, thereby realizing an enhanced field modulation effect. We obtain the best modulation performance by optimizing the structural parameters and changing the offset distance of the nanowires. Analysis of the simulation results indicate that the structure offers a high modulation depth (>0.13 dB / μm) covering the S , C, and L bands. Benefitting from the strong subwavelength confinement and excellent broadband modulation performance, the proposed optical waveguide modulators offer a significant potential to realize various long-wave integrated modulators, interconnects, and optoelectronic devices.

Calculation of Transmission Characteristics of Shielded Microstrip Lines Filled with Anisotropic Left-Handed and Right-Handed Materials

In this paper, the edge-based finite element formula for calculating the transmission characteristics of shielded microstrip lines filled with anisotropic materials with magnetic field as working variable is derived in detail. The filling materials include anisotropic left-handed materials and anisotropic right-handed materials, and the transmission characteristics include dominant mode cutoff wavelength and electric field structure. We mainly take Rectangular-shaped, V-shaped and Trapezoidal-shaped shielded microstrip lines as examples to calculate the transmission characteristics. The formulas and calculation examples derived in this paper have strong guiding significance for the application of anisotropic left-handed and right-handed materials in inhomogeneous transmission lines, which will further expand the use of shielded microstrip lines in optical devices such as electro-optic waveguide modulators.

High electro-optic coefficient lead zirconate titanate films toward low-power and compact modulators

Developing strong electro-optic (EO) effect materials and devices is vital for high-speed optical communications and integrated photonics. In this work, we explored a chemical solution deposition technique to grow pure perovskite lead zirconate titanate (PZT) films on sapphire substrates. The grown PZT films demonstrated a preferential orientation and a broadband optical transmission window ranging from 600 to 2500 nm. Based on the high-quality film, we subsequently designed and fabricated a PZT Mach-Zehnder interference waveguide EO modulator. The measured half-wave voltage Vπ is 3.6 V at the wavelength of 1550 nm, corresponding to an in-device EO coefficient as high as ∼133 pm/V. The response of the PZT modulator from 6 to 12 GHz has been measured. We foresee that our work may pave the way towards power-efficient, ultra-compact integrated devices, including modulators, switches and sensors.

All-Dielectric Graphene-induced T-Slot Waveguide Electro-Optic Modulator With Polarization-Independent Operation

Developing efficient techniques to realize polarization-independent modulators nowadays is still important for on-chip photonic circuits. Here, we propose and theoretically demonstrate a graphene-based T-slot waveguide modulator, which simultaneously supports the TE and TM polarized modes, offering a greater possibility to achieve the polarization-independent modulation. The modulation performance is comprehensively studied in terms of attenuation loss, insertion loss, modulation depth, normalized mode area, bandwidth and power consumption. Optimizations of key characteristic parameters illustrate that the modulator not only offers a mode confinement beyond the diffraction limit (<; λ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /12 and <; λ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /8 for TM and TE modes, respectively), but also exhibits an outstanding performance with a modulation depth (MD) of >0.35 dB/μm, a insertion loss (IL) of <; 0.1 dB/μm and a MD discrepancy of <; 0.012 dB/μm for both polarized modes covering the whole S, C and L bands. Particularly, the modulator possesses a compact footprint of 11.6 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , a 3-dB modulation bandwidth of 50 GHz and a power consumption per bit of 2.07 pJ/bit based on theoretical predictions. The polarization-independent operation is also quite robust against the possible fabrication perturbations. Our work may inspire new potential for developing the integrated modulators and opto-electronic interconnects in the advanced polarization-diversity circuits.

Ultracompact electro-optic waveguide modulator based on a graphene-covered λ/1000 plasmonic nanogap.

The extreme field confinement and electro-optic tunability of plasmons in graphene make it an ideal platform for compact waveguide modulators, with device footprints aggressively scaling orders of magnitude below the diffraction limit. The miniaturization of modulators based on graphene plasmon resonances is however inherently constrained by the plasmon wavelength, while their performance is bounded by material loss in graphene. In this report, we propose to overcome these limitations using a graphene-covered λ/1000 plasmonic nanogap waveguide that concentrates light on length scales more than an order of magnitude smaller than the graphene plasmon wavelength. The modulation mechanism relies on interference between the non-resonant background transmission and the transmission mediated by the gate-tunable nanogap mode, enabling modulation depths over 20 dB. Since the operation of the device does not rely on graphene plasmons, the switching behavior is robust against low graphene carrier mobility even under 1000 cm2/Vs, which is desirable for practical applications.

One-dimensional photonic crystal waveguide based on SOI platform for transverse magnetic polarization-maintaining devices

In this letter, a TM-polarization C-band pass one-dimensional photonic crystal strip waveguide (1D-PCSW) is presented. The waveguide structure is based on a silicon-on-insulator platform which is easy to realize using standard CMOS technology. The numerical study is conducted via 3D-finite element method (FEM). The transmittance and polarization extinction ratio (PER) is enhanced by optimizing the geometric parameters of the device. As a result, a TM polarized light can travel in the waveguide with ~2 dB loss for all C-band telecommunication wavelength window whereas the TE polarized light suffers a high transmission loss of &gt;30 dB. As a result, a PER of ~28.5 dB can be obtained for the whole C-band wavelengths range. The total length of the proposed device is around 8.4 µm long including 1 µm silicon strip waveguide segment on both ends. Based on our study presented in this paper, several photonic devices can be realized where strict polarization filtering is required. Full Text: PDF ReferencesB. Wang, S. Blaize, R.S-Montiel, "Nanoscale plasmonic TM-pass polarizer integrated on silicon photonics", Nanoscale, 11, 20685 (2019). CrossRef D. Dai, J.E. Bowers, "Silicon-based on-chip multiplexing technologies and devices for Peta-bit optical interconnects", Nanophotonics, 3, 283 (2014). CrossRef M.A. Butt, S.N. Khonina, N.L. Kazanskiy, "Optical elements based on silicon photonics", Computer Optics, 43, 1079 (2019). CrossRef M.A. Butt, S.N. Khonina, N.L. Kazanskiy, "Compact design of a polarization beam splitter based on silicon-on-insulator platform", Laser Physics, 28, 116202 (2018). CrossRef M.A. Butt, S.N. Khonina, N.L. Kazanskiy, "A T-shaped 1 × 8 balanced optical power splitter based on 90° bend asymmetric vertical slot waveguides", Laser Physics, 29, 046207 (2019). CrossRef Q. Wang, S.-T. Ho, "Ultracompact TM-Pass Silicon Nanophotonic Waveguide Polarizer and Design", IEEE Photonics J., 2, 49 (2010). CrossRef C.-H. Chen, L. Pang, C.-H. Tsai, U. Levy, Y. Fainman, "Compact and integrated TM-pass waveguide polarizer", Opt. Express, 13, 5347 (2005). CrossRef S. Yuan, Y. Wang, Q. Huang, J. Xia, J. Yu, "Ultracompact TM-pass/TE-reflected integrated polarizer based on a hybrid plasmonic waveguide for silicon photonics", in 11th International Conference on Group IV Photonics (GFP) (IEEE, 2014), pp. 183-184. CrossRef X. Guan, P. Chen, S. Chen, P. Xu, Y. Shi, D. Dai, "Low-loss ultracompact transverse-magnetic-pass polarizer with a silicon subwavelength grating waveguide", Opt. Lett., 39, 4514 (2014). CrossRef A.E.- S. Abd-Elkader, M.F. O. Hameed, N.F. Areed, H.E.-D. Mostafa, and S.S. Obayya, "Ultracompact AZO-based TE-pass and TM-pass hybrid plasmonic polarizers", J.Opt. Soc. Am. B., 36, 652 (2019). CrossRef J. Li et al., "Photonic Crystal Waveguide Electro-Optic Modulator With a Wide Bandwidth", Journal of Lightwave Technology, 31, 1601-1607 (2013). CrossRef N. Skivesen et al., "Photonic-crystal waveguide biosensor", Optics Express, 15, 3169-3176 (2007). CrossRef S. Lin, J. Hu, L. Kimerling, K. Crozier, "Design of nanoslotted photonic crystal waveguide cavities for single nanoparticle trapping and detection", Optics Letters, 34, 3451-3453 (2009). CrossRef T. Liu, A.R. Zakharian, M. Fallahi, J.V. Moloney, M. Mansuripur, "Design of a compact photonic-crystal-based polarizing beam splitter", IEEE Photonics Technology Letters, 17, 1435-1437 (2005). CrossRef R. K. Sinha, Y. Kalra, "Design of optical waveguide polarizer using photonic band gap", Optics Express, 14, 10790 (2006). CrossRef

Observation of a comb of squeezed states with a strong squeezing factor by a bichromatic local oscillator.

We demonstrate the experimental detection of an optical squeezing covering several higher resonances of the optical parametric amplifier (OPA) by adopting a bichromatic local oscillator (BLO). The BLO is generated from a waveguide electro-optic phase modulator (WGM) and subsequent optical mode cleaner (OMC), without the need of additional power balance and phase control. The WGM is used for generating the frequency-shifted sideband beams with equal power and certain phase difference, and the OMC is used for filtering the unwanted optical modes. Among a measurement frequency range from 0 to 16.64 GHz, the maximum squeezing factors are superior to 10 dB below the shot noise limit for the first three discrete odd-order resonances of the OPA.

Study of the stability of the fiber-optic current sensor

Optical fiber sensors are of particular interest for applications in the high-voltage environments of the electric power industry due to their characteristic properties including dielectric nature, immunity to electro-magnetic interference, and small size and weight. We have studied current sensor that employs the Faraday effect in the spun fiber and signal processing based on the additional harmonic modulation of the self-consistent polarization interferometer. We replaced the traditional PZT transducer with the LiNbO3 waveguide electro-optical modulator that allowed to increase significantly the modulation frequency and to reduce the length of the fiber delay line. Original error compensation methods allowed us to achieve the accuracy of ±0.2% in amplitude in the temperature range of about 50 °C.

Steady-State Analysis of the Effects of Residual Amplitude Modulation of InP-Based Integrated Phase Modulators in Pound–Drever–Hall Frequency Stabilization

Residual amplitude modulation of the phase modulator deployed in Pound-Drever-Hall frequency stabilization is an effect known to cause instabilities to the absolute wavelength of the stabilized laser. We present measurements and analysis of the residual amplitude modulation in an InP-based waveguide electro-optic phase modulator. The modulator is monolithically integrated in the output waveguide of a tuneable laser. The effects on the frequency stabilization of such a laser system to a reference etalon using a Pound-Drever-Hall frequency stabilization scheme are quantified. Frequency offset values in the stabilization point from the reference Fabry-Perot etalon resonance caused by the amplitude modulation are predicted and optimum operating points to minimize residual amplitude modulation are discussed. By operating an electro-refractive phase modulator at the proper bias point we show that frequency offsets corresponding to less than 3×10 ^{-3}$ of the reference cavity full-width half-maximum can be achieved.

Design of graphene-on-germanium waveguide electro-optic modulators at the 2μm wavelength

The spectral region around 2μm wavelengths is of special significance for applications in optical communications, which is facing a capacity crunch at the telecommunication band. Development of CMOS-compatible on-chip photonic and optoelectronic devices operating in this spectral region is highly demanded but still at its infancy. In this paper, we present a design of graphene-on-germanium slot waveguides at the wavelength of 2μm. Due to the optical-field enhancement and poor mode confinement, light-matter interactions are enhanced in the graphene-on-germanium slot waveguide. Moreover, the influence of the refractive index contrast and the number of integrated graphene layers on the optical absorption enhancement of the slot waveguide is studied. Based on the graphene-on-slot waveguide configuration, energy-efficient and compact Mach-Zehnder interferometer and microring resonator phase modulators are designed. Our study paves the way for the development of on-chip electro-optic modulators at 2μm wavelengths.

All-in-fiber SESAM based comb oscillator with an intra-cavity electro-optic modulator for coherent high bandwidth stabilization.

We demonstrate the stabilization of an all-in-fiber polarization maintaining semi-conductor saturable absorber mirror (SESAM) mode locked frequency comb oscillator with an intra-cavity waveguide electro-optic phase modulator (EOM) to a narrow linewidth HeNe laser over 46 hours. The high feedback bandwidth of the EOM allows a coherent optical lock with an in-loop integrated phase noise of 1.12 rad (integrated from 10 Hz to 3 MHz) from the carrier signal. No piezo fiber stretcher was required to guarantee long-term stabilization, preventing mechanical degradation of the optical fibers and enabling a long lifetime of the oscillator. As an application a hybrid stabilization scheme is presented, where a comb tooth is phase locked to a longitudinal mode of the large ring laser "G" located at the Geodatic Observatory Wettzell. The hybrid stabilization scheme describes the optical lock of the frequency comb to the G laser and the simultaneous compensation of the ring laser frequency drift by comparing the comb repetition rate against an active H-maser reference. In this context the ring laser reached a fractional Allan deviation of 5 · 10-16 at an integration time of 16384 s.

Compact Amplitude Electro-Optic Modulator Based on Chromophore-Containing Polyimides

This paper describes the development and investigation of compact waveguide electrooptic modulators using original synthesized chromophore-containing polyimides with covalently attached commercial DR-13 dye. Fully polymer planar electro-optic structures with phase-polarization and amplitude modulators in the form of a Mach–Zehnder interferometer were developed and implemented. The characteristics of the developed modulators at a wavelength of 1.3 μm were investigated, and a half-wave voltage of 24 V was achieved with a 1.3 cm length of the active part of the modulator.

All-organic electro-optic waveguide modulator comprising SU-8 and nonlinear optical polymer.

In this paper we describe the principles of operation as well as the fabrication and testing steps of an all-organic waveguide modulator. The modulator comprises an SU-8 core and an electro-optic host-guest polymer cladding. The polymer properties are tuned in order to achieve single mode operation. We used direct-write laser lithography in two steps for the preparation of the devices. The electro-optic coefficient of the polymer is estimated from observing the modulation of the device operated in push-pull mode.

Transparent conducting oxide electro-optic modulators on silicon platforms: A comprehensive study based on the drift-diffusion semiconductor model

Electro-optic waveguide modulators exploiting the carrier-induced epsilon-near-zero effect in transparent conducting oxides are comprehensively studied and evaluated using a rigorous multi-physics modeling framework. The examined amplitude modulators integrate indium tin oxide with two representative examples of the silicon-on-insulator technology, the silicon-rib and silicon-slot platform, with the latter design exhibiting superior performance, featuring μm modulation lengths, switching speeds exceeding 100 GHz, and a sub-pJ per bit of energy consumption. The effect of free carriers is rigorously introduced by combining the drift-diffusion model for the description of the carrier dynamics with near-infrared carrier-dependent permittivity models, leading to a seamless and physically consistent integration of solid-state physics and Maxwell wave theory on a unified finite-element platform.