Organic electro-optic polymer materials and organic-based hybrid electro-optic modulators

High performance electro-optic modulator,as the key device of integrated ultra-wideband optical systems,have be-come the focus of research.Meanwhile,the organic-based hybrid electro-optic modulators,which make full use of the advant-ages of organic electro-optic(OEO)materials(e.g.high electro-optic coefficient,fast response speed,high bandwidth,easy pro-cessing/integration and low cost)have attracted considerable attention.In this paper,we introduce a series of high-perform-ance OEO materials that exhibit good properties in electro-optic activity and thermal stability.In addition,the recent progress of organic-based hybrid electro-optic devices is reviewed,including photonic crystal-organic hybrid(PCOH),silicon-organic hy-brid(SOH)and plasmonic-organic hybrid(POH)modulators.A high-performance integrated optical platform based on OEO ma-terials is a promising solution for growing high speeds and low power consumption in compact sizes.

Polymer Electro-optic Modulator Linear Bias Using the Thermo-optic Effect

A quasi-rectangular waveguide polymer MacH^(-)Zehnder (M-Z) electro-optic (EO) modulator based on an organic/inorganic hybrid material with thermal bias control is fabricated and demonstrated.Linear bias for the modulator is obtained through thermo-optic effect.The optical output is adjusted by changing phase difference between the two arms of the M-Z interferometer.A power consumption of 16.1 m W for π phase change is observed owing to the application of silica cladding.This approach is proved to be effective to suppress direct current drift in polymer EO modulators.

Waveguide electro-optic modulators based on self-assembled material systems

Fabrication and characterization of electro-optic modulators based on the novel organic electro-optic materials composed of self-assembled superlattices (SAS) were presented, both wet-dipping self-assembly and vapor phase deposition approaches were discussed. Prototype waveguide electro-optic modulators were fabricated using SAS films integrated with low-loss polymeric materials functioning as partial guiding and cladding layers.Promising electro-optic thin film materials including DTPT and PEPCOOH grown from the vapor phase were used for fabrication and test of electro-optic prototype modulators. Finally,the EO coefficient of tens of pm/V was obtained,which can sufficiently support high-speed and small size EO modulators.

Recent Progress in Silicon Electro-optic Modulators for High Speed Applications

Silicon-based high-speed electro-optical modulator is the key component of silicon photonics for future communiction and interconnection systems. In this paper, introduced are the optical mudulation mechanisms in silicon, reviewed are some recent progresses in high-speed silicon modulators, and analyzed are advantages and shortages of the silicon modulators of different types.

Simulation design of thin film lithium niobate electro-optic modulator with bimetallic layer electrodes

Thin-film lithium niobate electro-optical modulator will become the key device in the future optical communication,which has the advantages of high modulation rate,low half-wave voltage,large bandwidth,and easy integration compared with conventional bulk lithium niobate modulator.However,because the electrode gap of the lithium niobate film modulator is very narrow,when the microwave frequency gets higher,it leads to higher microwave loss,and the electro-optical performance of the modulator will be greatly reduced.Here,we propose a thin film lithium niobate electro-optic modulator with a bimetallic layer electrode structure to achieve microwave loss less than 8 dB/cm in the range of 200 GHz,exhibiting a voltage-length product of 1.1 V·cm and a 3 dB electro-optic bandwidth greater than 160 GHz.High-speed data transmission test has been performed,showing good performance.

Low-loss and broadband complementary dual-output electro-optic modulator based on thin-film lithium niobate

Broadband,low-drive voltage electro-optic modulators are crucial optoelectronic components in the new-generation microwave photonic links and broadband optical interconnect network applications.In this paper,we fabricate a low-loss thinfilm lithium niobate complementary dual-output electro-optic modulator chip with a 3 dB electro-optic bandwidth of 59 GHz and a half-wave voltage(Vπ)of 2.5 V.The insert-loss of the packaged modulator is 4.2 dB after coupling with polarizationmaintaining fiber.The complementary dual-output modulator also shows a common-mode rejection ratio of 18 dB and a signal enhancement of 6.2 dB when adapted in microwave photonic links,comparable to commercial bulk lithium niobate devices.

Wavelength injection locking actively Q-switched random fiber laser based on random phase-shifted fiber Bragg grating and electro-optic modulator

In this paper, an actively Q-switched wavelength injection locking random fiber laser(RFL) based on random phase-shifted fiber Bragg grating(RPS-FBG) is proposed, and the performance of the laser is verified by experiments. Within the reflection bandwidth range of RPS-FBG, spanning from 1 549.2 nm to 1 549.9 nm, different laser modes with stable central wavelength and peak power can be selectively chosen by varying the injected light wavelength. The power fluctuation within 1 h is less than 0.1 d Bm, and the central wavelength drift is less than 0.02 nm. When the pump power increases from 90 mW to 300 mW, the pulse width decreases from 3.2 μs to 1.5 μs, and the pulse repetition frequency is 20 kHz. The RFL can reach a stable locking state at the lowest pump power of 100 mW and the lowest injection power of 3 d Bm. When the wavelength is locked, the output pulse is a single pulse. On the contrary, the unlocked output pulse is multi-pulse. The laser has the characteristics of high wavelength tunability in the reflection range of RPS-FBG and it can be an ideal light source in the fields of laser imaging and pulse coding.

Mach-Zehnder Electro-Optic Polymer Modulator with C orona Poled Core Layer

A Mach-Zehnder(MZ) electro-optic(EO) modulator are real iz ed,with three optical layers as polymer materials.The functional layer is the co rona poled crosslinkable polyurethane.The ridge waveguide is fabricated by using the spin-coating,poling,photolithography and oxygen reactive ion etching(RIE) techniques.The mode and the modulation properties of these devices are demonstra ted in a micron control system,while the light source works at the wavelength of 1 31 or 1 55 micron.

A High-Performance Silicon Electro-Optic Phase Modulator with a Triple MOS Capacitor

We propose and analyze a novel Si-based electro-optic modulator with an improved metal-oxide-semiconductor （MOS） capacitor configuration integrated into silicon-on-insulator （SOl）. Three gate-oxide layers embedded in the silicon waveguide constitute a triple MOS capacitor structure, which boosts the modulation efficiency compared with a single MOS capacitor. The simulation results demonstrate that the Vπ Lπ product is 2. 4V · cm. The rise time and fall time of the proposed device are calculated to be 80 and 40ps from the transient response curve, respectively,indicating a bandwidth of 8GHz. The phase shift efficiency and bandwidth can be enhanced by rib width scaling.

Monolithic thin film lithium niobate electro-optic modulator with over 110 GHz bandwidth

High-performance thin film lithium niobate(LN) electro-optic modulators with low cost are in demand. Based on photolithography and wet etching, we experimentally demonstrate a thin film LN Mach–Zehnder modulator with a 3 d B bandwidth exceeding 110 GHz, which shows the potential of boosting the throughput and reducing cost. The fabricated modulator also exhibits a comparable low half-wave voltage-length product of ~2.37 V · cm, a high extinction ratio of >23 d B, and the propagation loss of optical waveguides of ~0.2 d B/cm. Besides, six-level pulse amplitude modulation up to 250 Gb/s is successfully achieved.

The effect of conductor loss on half-wave voltage and modulation bandwidth of electro-optic modulators

In this paper, we theoretically deduce the expressions of half-wave voltage and 3-dB modulation bandwidth in which conductor loss is taken into account. The results suggest that it will affect the theoretical values of half-wave voltage and bandwidth as well as the optimized electrode's dimension whether considering the conductor loss or not. As an example, we present a Mach-Zehnder (MZ) type polymer waveguide amplitude modulator. The half-wave voltage increases by 1 V and the 3-dB bandwidth decreases by 30% when the conductor loss is taken into account. Besides, the effects of impedance mismatching and velocity mismatching between microwave and light wave on the half-wave voltage, and 3-dB bandwidth are discussed.

Design optimization of microwave properties for polymer electro-optic modulator using full vectorial finite element method

In this paper, a polymer electro-optic mod- ulator has been designed and optimized using the full vectorial finite element method. For this purpose, the effects of magnesium oxide （MgO） and down cladding thicknesses, distance between two ground electrodes, hot electrode and modulator widths modulator on the key modulator parameters, such as microwave effective index r/m, the characteristic impedance Zc and the microwave losses a are presented. After selecting optimal dimensions of polymer electro-optic modulator, frequency dependent aforementioned parameters and the half-wave voltage- length product （VπL） parameter of polymer electro-optic modulator are extracted and as a consequence, an optimized design is reported. Finally, the optical and electrical modulation responses of polymer electro-optic modulator are calculated. The optimized polymer electro- optic modulator exhibits 3-dB electrical bandwidth of 260 GHz and VπL about 2.8 V- cm in this frequency.

Ridge Waveguide Electro-Optic Polymer Modulator with a New Kind of Corona Poled Crosslinkable Polyurethane

A polymer electro optic modulator has been fabricated with the functional layer acting as a kind of corona poled crosslinkable polyurethane. The three optical layers, namely waveguide, photolithography and oxygen are fabricated by spin coating. With the Reactive Ion Etching method, the ridge of the waveguide is constructed. With light at 1 31μm being fiber coupled to waveguide, the mode and the modulation properties of these devices are demonstrated in a micron control system.

Structure Design of Polymer Electro-Optic Modulator with Ultra- Broadband

Using finite element method, lots of calculating focusing on polymer electro-optic modulators with ultra-broadband were done, a few structures were analyzed. Coplanar waveguide electrode system was advanced, a few real examples was given.

Low-power electro-optic phase modulator based on multilayer graphene/silicon nitride waveguide

Electro-optic modulator is a key component for on-chip optical signal processing.An electro-optic phase modulator based on multilayer graphene embedded in silicon nitride waveguide is demonstrated to fulfill low-power operation.Finite element method is adopted to investigate the interaction enhancement between the graphene flake and the optical mode.The impact of multilayer graphene on the performance of phase modulator is studied comprehensively.Simulation results show that the modulation efficiency improves with the increment of graphene layer number,as well as the modulation length.The 3-dB bandwidth of around 48 GHz is independent of graphene layer number and length.Compared to modulator with two-or four-layer graphene,the six-layer graphene/silicon nitride waveguide modulator can realizeπphase shift at a low-power consumption of 14 fJ/bit when the modulation length is 240μm.

Influence of substrate effect on near-field radiative modulator based on biaxial hyperbolic materials

Relative rotation between the emitter and receiver could effectively modulate the near-field radiative heat transfer(NFRHT)in anisotropic media.Due to the strong in-plane anisotropy,natural hyperbolic materials can be used to construct near-field radiative modulators with excellent modulation effects.However,in practical applications,natural hyperbolic materials need to be deposited on the substrate,and the influence of substrate on modulation effect has not been studied yet.In this work,we investigate the influence of substrate effect on near-field radiative modulator based onα-MoO_(3).The results show that compared to the situation without a substrate,the presence of both lossless and lossy substrate will reduce the modulation contrast(MC)for different film thicknesses.When the real or imaginary component of the substrate permittivity increases,the mismatch of hyperbolic phonon polaritons(HPPs)weakens,resulting in a reduction in MC.By reducing the real and imaginary components of substrate permittivity,the MC can be significantly improved,reaching 4.64 forε_(s)=3 at t=10 nm.This work indicates that choosing a substrate with a smaller permittivity helps to achieve a better modulation effect,and provides guidance for the application of natural hyperbolic materials in the near-field radiative modulator.

Calcium-sensitive protein MLC1 as a possible modulator of the astrocyte functional state

Astrocytes,the main population of glial cells in the central nervous system(CNS),exert essential tasks for the control of brain tissue homeostasis,supporting neuron and other glial cell activity from the developmental stage to adult life.To maintain the optimal functionality of the brain,astroglial cells are particularly committed to reacting to every change in tissue homeostatic conditions,from mild modifications of the physiological environment,a process called astrocyte activation,to the more severe alterations occurring in pathological situations causing astrocyte reactivity or reactive astrogliosis(Escartin et al.,2021).During these reactive states,astrocytes mount an active,progressive response encompassing morphological,molecular,and interactional remodeling,leading to the acquisition of new functions and the loss of others,whose intensity,duration,and reversibility are dependent on the nature of the stimulus and regulated in a context-specific manner.

Neuropeptide cholecystokinin:a key neuromodulator for hippocampal functions

Spatial memory is crucial for survival within external surroundings and wild environments.The hippocampus,a critical hub for spatial learning and memory formation,has received extensive investigations on how neuromodulators shape its functions(Teixeira et al.,2018;Zhang et al.,2024).However,the landscape of neuromodulations in the hippocampal system remains poorly understood because most studies focus on classical monoamine neuromodulators,such as acetylcholine,serotonin,dopamine,and noradrenaline.The neuropeptides,comprising the most abundant neuromodulators in the central nervous system,play a pivotal role in neural information processing in the hippocampal system.Cholecystokinin(CCK),one of the most abundant neuropeptides,has been implicated in regulating various physiological and neurobiological statuses(Chen et al.,2019).CCK-A receptor(CCK-AR)and CCK-B receptors(CCK-BR)are two key receptors mediating the biological functions of CCK,both of which belong to class-A sevenfold transmembrane G protein-coupled receptors(Nishimura et al.,2015).CCK-AR preferentially reacts to sulfated CCK,whereas CCK-BR binds both CCK and gastrin with similar affinities(Ding et al.,2022).The expression patterns of CCK-AR and CCK-BR are distinct,implying that CCK has various functions in target regions.For instance,CCK-AR is widely expressed in the GI and brain subregions and is hence implicated in the control of digestive function and satiety regulation.Conversely,CCK-BR is abundantly and widely distributed in the central nervous system,which majorly regulates anxiety,learning,and memory(Ding et al.,2022).However,the roles of endogenous CCK and CCK receptors in regulating hippocampal function at electrophysiological and behavioral levels have received less attention.

Exploring the modulatory role of bovine lactoferrin on the microbiome and the immune response in healthy and Shiga toxin‑producing E.coli challenged weaned piglets

Background Post-weaned piglets suffer from F18+Escherichia coli(E.coli)infections resulting in post-weaning diar-rhoea or oedema disease.Frequently used management strategies,including colistin and zinc oxide,have contrib-uted to the emergence and spread of antimicrobial resistance.Novel antimicrobials capable of directly interacting with pathogens and modulating the host immune responses are being investigated.Lactoferrin has shown promising results against porcine enterotoxigenic E.coli strains,both in vitro and in vivo.Results We investigated the influence of bovine lactoferrin(bLF)on the microbiome of healthy and infected weaned piglets.Additionally,we assessed whether bLF influenced the immune responses upon Shiga toxin-producing E.coli(STEC)infection.Therefore,2 in vivo trials were conducted:a microbiome trial and a challenge infection trial,using an F18+STEC strain.BLF did not affect theα-andβ-diversity.However,bLF groups showed a higher relative abundance(RA)for the Actinobacteria phylum and the Bifidobacterium genus in the ileal mucosa.When analysing the immune response upon infection,the STEC group exhibited a significant increase in F18-specific IgG serum levels,whereas this response was absent in the bLF group.Conclusion Taken together,the oral administration of bLF did not have a notable impact on theα-andβ-diversity of the gut microbiome in weaned piglets.Nevertheless,it did increase the RA of the Actinobacteria phylum and Bifi-dobacterium genus,which have previously been shown to play an important role in maintaining gut homeostasis.Furthermore,bLF administration during STEC infection resulted in the absence of F18-specific serum IgG responses.

Light-field modulation and optimization near metal nanostructures utilizing spatial light modulators

Plasmonic modes within metal nanostructures play a pivotal role in various nanophotonic applications.However,a significant challenge arises from the fixed shapes of nanostructures post-fabrication,resulting in limited modes under ordinary illumination.A promising solution lies in far-field control facilitated by spatial light modulators(SLMs),which enable on-site,real-time,and non-destructive manipulation of plasmon excitation.Through the robust modulation of the incident light using SLMs,this approach enables the generation,optimization,and dynamic control of surface plasmon polariton(SPP)and localized surface plasmon(LSP)modes.The versatility of this technique introduces a rich array of tunable degrees of freedom to plasmon-enhanced spectroscopy,offering novel approaches for signal optimization and functional expansion in this field.This paper provides a comprehensive review of the generation and modulation of SPP and LSP modes through far-field control with SLMs and highlights the diverse applications of this optical technology in plasmon-enhanced spectroscopy.