Synthesis and characterization of electro-optic waveguide material polyurethane-imides

In an on-chip silicon-organic hybrid electro-optic (EO) modulator, the mode overlap with EO materials, in-device effective r33, and propagation loss are among the most critical factors that determine the performance of the modulator. Various waveguide structures have been proposed to optimize these factors, yet there is a lack of comprehensive consideration on all of them. In this Letter, a one-dimensional (1D) photonic crystal (PC) slot waveguide structure is proposed that takes all these factors into consideration. The proposed structure takes advantage of the strong mode confinement within a low-index region in a conventional slot waveguide and the slow-light enhancement from the 1D PC structure. Its simple geometry makes it robust to resist fabrication imperfections and helps reduce the propagation loss. Using it as a phase shifter in a Mach-Zehnder interferometer structure, an integrated silicon-organic hybrid EO modulator was experimentally demonstrated. The observed effective EO coefficient is as high as 490 pm/V. The measured half-wave voltage and length product is less than 1 V·cm and can be further improved. A potential bandwidth of 61 GHz can be achieved and further improved by tailoring the doping profile. The proposed structure offers a competitive novel phase-shifter design, which is simple, highly efficient, and with low optical loss, for on-chip silicon-organic hybrid EO modulators.

The novel electro-optic (EO) polymers of fluorinated cross-linkable polyurethane-imides (CLPUI) were designed and synthesized by polycondensation of azo chromophore C1 and C2, diisocyanate MDI, and aromatic dianhydride 6FDA. Molecular structural characterization for the resulting polymers was achieved by 1HNMR, FT-IR, elemental analysis, and gel permeation chromatography. The polymers exhibit good film-forming properties, high glass transition temperature (Tg) in the range of 193–200 °C, and thermal stability up to 290 °C. The polymers that possess a high EO coefficient (\(\gamma_{33}\) = 48 and 56 pm/V) at 1550 nm for poled polymer thin films were measured by the simple reflection technique. Excellent temporal stability and low optical losses in the range of 1.1–1.7 dB/cm at 1550 nm were observed for these polymers. Using the synthesized side-chain electro-optic CLPUI as the active core material and of a fluorinated polyimide as cladding material, we have designed and successfully fabricated the high-performance polymer waveguide Mach–Zehnder EO modulators.

Optimizing low half-wave voltage electro-optic polymer modulator for optical waveguide sensor

An all-fiber structured electro-absorption (EA) modulator based on quadri-layer graphene is proposed. The quadri-layer graphene is directly built into the core of the fiber to ensure the coupling efficiency. Mode analysis is used to reveal the light modulation mechanism under the anisotropic graphene modeling, which is merely conducted in previous studies. Compared with conventional semiconductor EA modulators, it exhibits an excellent performance with the advantages such as small footprint (12.9 µm), high modulation depth (0.233 dB/ µm), small voltage swing (0.2 V), low energy consumption and broad operation bandwidth. In addition, the proposed modulator features simple structure, low optical propagation and coupling loss, and good integrated compatibility as the fiber modulator. All these edges prospect the great potentiality in future high-speed optic fiber communications, optical signal processing, and all-fiber systems.

Electro-optic (EO) modulator is a device used primarily in optical communication systems to provide an external optical high-speed bandwidth modulation. Instead, the EO modulator can also be employed as sensing instrument with some modification. In this paper, we demonstrate the performance study of a polymer EO phase modulator compared with the commonly used waveguide material LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> to obtain better low insertion loss and length extension. Both parameters are substantial for biosensing applications such as biomedical equipment to detect human body response.

Microwave wireless and optical fiber technologies are widely used for several applications in communication, sensing, imaging, and so on. We propose an electro-optic (EO) modulator with a planar stripline feed to a gap-embedded patch-antenna for hybrid uplinks to an optical fiber and microwave wireless networks. The proposed device is designed on an EO crystal with simple and compact structure. The gap-embedded patch-antenna on the EO modulator can be operated for optical modulation to the optical fiber network. The proposed device can be also operated for microwave transmission to the air or wireless networks. Characteristic and analysis of the designed device for optical modulation and wireless microwave transmission are reported and discussed.

Electro-optic (EO) modulation is of interest to impart information onto an optical carrier. Inorganic crystals-most notably LiNbO3 and BaTiO3-exhibit EO modulation and good stability, but are difficult to integrate with silicon photonic technology. Solution-processed organic EO materials are readily integrated but suffer from thermal degradation at the temperatures required in operating conditions for accelerated reliability studies. Hybrid organic-inorganic metal halide perovskites have the potential to overcome these limitations; however, these have so far relied on heavy metals such as lead and cadmium. Here, we report linear EO modulation using metal-free perovskites, which maintain the crystalline features of the inorganic EO materials and incorporate the flexible functionality of organic EO chromophores. We find that, by introducing a deficiency of cations, we reduce the symmetry in the perovskite crystal and produce thereby an increased EO response. The best-engineered perovskites reported herein showcase an EO coefficient of 14 pm V-1 at a modulation frequency of 80 kHz, an order of magnitude higher than in the nondefective materials. We observe split peaks in the X-ray diffraction and neutron diffraction patterns of the defective sample, indicating that the crystalline structure has been distorted and the symmetry reduced. Density functional theory (DFT) studies link this decreased symmetry to NH4+ deficiencies. This demonstration of EO from metal-free perovskites highlights their potential in next-generation optical information transmission.

Electro-optic (EO) modulators play a critical role in converting electrical signals into optical signals. With the growing demand for higher data traffic and broader network bandwidth, there is an increasing need for high-performance, highly integrated EO modulators. Thin-film lithium niobate (TFLN) modulators have emerged as a promising solution for next-generation integrated photonic circuits due to their low power consumption, wide bandwidth, compact footprint, and well-established fabrication process. Our research proposes a Mach–Zehnder modulator (MZM) based on silicon-based TFLN, aiming to achieve a balance between low half-wave voltage product (V π ·L), low optical loss, and high bandwidth. Through systematic design of the waveguide geometry and cladding structure, we demonstrate a modulator with a V π ·L of 0.69 V·cm, a propagation loss of 0.578 dB cm −1 , and a 3-dB bandwidth exceeding 110 GHz at 1550 nm.

A large band gap, high refractive index, and a non-zero electro-optic coefficient distinguish aluminum nitride as a wave-guiding material, particularly for photonic integrated circuits in the visible to ultraviolet wavelength range. However, the electro-optic coefficient is modest, typically requiring over 100 V to switch a Mach–Zehnder style modulator (V π L π &gt;200 Vcm). This paper demonstrates the combined use of thermo-optic and electro-optic tuning, using the same electrodes simultaneously for both types of tuning. This combination tuner achieves the tuning bandwidth of a purely electro-optic approach with the tuning range of a purely thermo-optic approach while adding no additional nanofabrication steps. The only additional complexity is in the off-chip control electronics. To demonstrate the benefit of a combination tuner approach, we present two sample applications of its use with an aluminum nitride micro-ring modulator: data transfer through electro-optic modulation and stabilizing the transmission intensity against environmental perturbations.

Lithium niobate on insulator (LNOI) is a promising material platform for applications in integrated quantum photonics. A low optical loss is crucial for preserving fragile quantum states. Therefore, in this study, we have fabricated LNOI rib waveguides with a low optical propagation loss of 0.16 dB/cm by optimizing the etching conditions for various parameters. The symmetry and smoothness of the waveguides on ‐cut LNOI are improved by employing a shallow etching process. The proposed method is expected to facilitate the development of on‐chip quantum photonic devices based on LNOI.

For the polarization switching (PS) and the nonlinear dynamic behaviors (NDBs) of the optically injected laser system composed of master vertical-cavity surface-emitting laser (M-VCSEL) and slave vertical-cavity surface-emitting laser (S-VCSEL), we put forward a novel manipulation scheme and explore their control law by means of electro-optic (EO) modulation with quasi-phase matched technology in periodically poled LiNbO3. It is found that the PS of the S-VCSEL subjected to parallel or orthogonal optical injection undergoes a change of periodic oscillation with the applied transverse electric field. The envelope trajectory of the oscillation peak appears to be a cosine curve, and that of the oscillation wave trough becomes a sine curve. Besides, the PS of the S-VCSEL only depends on the applied transverse electric field and the bias current of the M-VCSEL, and is independent of the bias current of the S-VCSEL. When the bias current of the M-VCSEL takes a different value, the PS of the S-VCSEL shows a different evolution law in one period of the applied electric field. For a certain fixed bias current of the M-VCSEL, the optically injected S-VCSEL can emit an arbitrary polarization mode and its NDBs experience different evolutions when the light from the M-VCSEL goes through EO intensity modulation. If the output light of the M-VCSEL is subjected to EO intensity modulation and EO phase modulation simultaneously, while the bias current of the S-VCSEL is fixed at 1.06, that of the M-VCSEL is fixed at 1.18, and the optical injection strength is set at 5 ns-1, then the output polarization of the S-VCSEL is in turn switched from the y-LP to the left-handed elliptic polarization (EP), then the right-handed EP circular polarization, and lastly the left-handed EP. And its NDB shows in turn a single period, four doubled periods, chaos, four doubled periods, and chaos with the increase of the applied electric field.

A deoxyribonucleic acid (DNA) biopolymer has been studied for use as a conductive cladding layer in polymer electro-optic (EO) waveguide modulators due to its low optical loss and high electrical conductivity relative to its inorganic polymer counterparts. Electric field contact poling measurements using a DNA biopolymer cladding layer with an amorphous polycarbonate/chromophore (APC/CLD1) guest-host system core layer have been made and compared to a UV15 cladding layer. Using the EO coefficient of APC/CLD1 with no cladding layer as a baseline, the DNA biopolymer cladding layer yielded relative poling efficiencies of 96% while the UV15 poling efficiencies were only 51%.

We have synthesized and evaluated nonlinear optical (NLO) properties of azo dye attached novel NLO polymers with high optical nonlinearity and/or high thermal stability. An azo-dye attached NLO polymer with a furan derivative as an acceptor was synthesized. The second order NLO susceptibility (χ(2) 33) at 1.3 μm fundamental wavelength was more than two times larger than that of the NLO polymer with dicyanovinyl (DCV) acceptor and the same azobenzene structure. A χ (2) 33 of 43pm/V was obtained. Polymethacrylic acid reacted with a typical azo dye, Disperse Red 1 dye (DR-1), in its side-chain was also synthesized using a new approach, i.e., via intermediate reaction of the acid and N,N'- dicyclohexylcarbodiimide. Glass transition temperatures Tg of 170°C were obtained for the dye attached polymethacrylic acid with the DR- 1 contents of 29 mol%. A χ (2) 33 of 53pm/V at 1.3 μm was obtained. This polymer can be further improved to have more stablility by heat treatment. Through this treatment, the methacryl imide structure was formed and the polymer has Tg of 165°C. This imidized polymer exhibited a χ (2) 33 of 45 pm/V at 1.3 μm and maintained about 90% of its initial value after 230 hours or more at 100°C. Novel NLO polyarylethers where electron-withdrawing groups for NLO activity were introduced into the polymers by post-functionalization were developed. These NLO polyarylethers have high Tgs, typically higher than 200°C. A 100 mol% DR-1 dye containing NLO polymer with the fluorene structure has very low optical propagation loss of 0.42dB/cm at 1.3 μm wavelength and shows low polarized light dependence of the refractive indices. The polymer has χ (2) 33 of about 57pm/V at 1.3|um fundamental wavelength and the nonlinearity was maintained at 100°C for more than 200 hrs Key words: second order nonlinear optics, nonlinear optical polymers, thermal stability, furan derivative, polymethacrylic acid, azo dye, imidization, polyarylether

The thin-film lithium niobate (TFLN)-based electro-optic (EO) modulator is one of the most important devices for optical communications in terms of the advantages of low voltages and large bandwidth. However, the large size of devices limits their applicability in large-scale integrated optical systems, posing a key challenge in maintaining performance advantages under restricted design space. In this paper, we propose a novel TFLN modulator on a quartz substrate incorporating barium titanate (BaTiO3, BTO) as the cladding material. The device is designed with silicon–lithium niobate (Si-LN) hybrid waveguides for operation at a wavelength of 1.55 µm. After theoretical analysis and parameter optimization, the proposed 10 mm long modulator demonstrates high-efficiency modulation, featuring a low half-wave voltage-length product of 1.39 V·cm, a broad 3 dB EO bandwidth of 152 GHz, and low optical loss. This theoretical model provides a novel design solution for TFLN modulators on quartz substrates. Moreover, it is a promising solution for enhancing the integration of photonic devices on the TFLN platform.

Simulations for dual-rail driven electro-optic modulators of BaTiO3 crystal thin-film waveguides