Integrated Optical Devices Research Articles

Highly Reversible Tuning of Light‐Matter Interactions in Van der Waals Materials Coupled with Hydrogel‐Assisted Optical Cavity

AbstractControlling light‐matter interactions via cavity systems manifested by Rabi splitting is paramount important for nanophotonics. However, achieving conveniently accessible and active tuning of light‐matter interactions remains a formidable challenge. Traditional approaches often necessitate either sophisticated design or meticulous nanofabrication to address this issue. Here, a handy strategy is experimentally demonstrated to build an adjustable coupling system featuring reversibly modulated responses based on dielectric‐hydrogel‐metal resonators. By controlling the top tungsten disulfide layer thickness, the flexible manipulation of weak‐intermediate‐strong transitions in exciton‐cavity interactions is revealed on a large‐scale hydrogel membrane without nanopositioning or lithography. Crucially, by leveraging the inflation sensitivity of the hydrogel, the coupling strength can be reversibly tailored with excellent reproducibility by modulating the resonator's dry/immersed states. The combined merits of captivating design and daily stimulus render the novel hydrogel‐based nanocavities as a groundbreaking step toward the development of active and practical integrated optical devices, such as polariton lasing, switches, and sensors.

Isolation of Single Donors in ZnO.

The shallow donor in zinc oxide (ZnO) is a promising semiconductor spin qubit with optical access. Single indium donors are isolated in a commercial ZnO substrate using plasma focused ion beam (PFIB) milling. Quantum emitters are identified optically by spatial and frequency filtering. The indium donor assignment is based on the optical bound exciton transition energy and magnetic dependence. The emission stability of these single donors in terms of both intensity and frequency, alongside their transition linewidths less than twice the lifetime limit, highlight the promise of single In donors as optically accessible spin qubits. The optical stability of single donors after FIB fabrication is promising for optical device integration required for scalable quantum technologies based on single donors in direct band gap semiconductors.

Design of high-efficiency InP/InGaAsP diluted waveguide for edge couplers

To transition integrated optical communication devices from laboratory settings to practical applications, efficient coupling between optical fibers and chip waveguides remains pivotal. This paper presents a systematic design of a diluted waveguide, a key component in the edge couplers of photonic integrated circuits. The primary purpose of the diluted waveguide lies in facilitating superior edge coupling with fiber waveguides, thereby seamlessly integrating external light sources into the waveguide structure. To commence, we employ the transfer matrix and effective refractive index techniques to simplify the 3-dimensional diluted waveguide into 2-dimensional multi-layer slab waveguides. By computing the field distribution of the fundamental mode within the diluted waveguide, the fiber-to-waveguide coupling efficiency can be derived using a simplified overlap equation and optimized diluted waveguide structure through particle swarm optimization algorithms. Consequently, we achieve a remarkable fiber-to-waveguide coupling efficiency exceeding 95% for TE-mode and 92% for TM-mode, with a polarization dependent loss (PDL) of merely 0.13 dB. Interestingly, the optimized diluted waveguide exhibits quasi-single mode behavior, as the fundamental mode containing 98% of the total energy propagates within it. Additionally, the diluted waveguide edge coupler demonstrates favorable alignment tolerance, with 1-dB excess losses of ±2.3 μm and (−2.5, +3) μm along the horizontal and vertical directions, respectively. Notably, our approach offers a versatile methodology for designing multi-layer waveguides across various materials. This method has the potential to be universally applied.

An integrated magnetic separation enzyme-linked colorimetric sensing platform for field detection of Escherichia coli O157: H7 in food.

Anintelligent colorimetric sensing platform integrated with in situ immunomagnetic separation function was developed for ultrasensitive detection of Escherichia coli O157: H7 (E. coli O157: H7) in food. Captured antibody modified magnetic nanoparticles (cMNPs) and detection antibody/horseradish peroxidase (HRP) co-functionalized AuNPs (dHAuNPs) were firstly synthesized for targeted enrichment and colorimetric assay of E. coli O157: H7, in which remarkable signal amplification was realized by loading large amounts of HRP on the surface of AuNPs. Coupling with the optical collimation attachments and embedded magnetic separation module, a highly integrated optical device was constructed, by which in situ magnetic separation and high-quality imaging of 96-well microplates containing E. coli O157: H7 was achieved with a smartphone. The concentration of E. coli O157: H7 could be achieved in one-step by performing digital image colorimetric analysis of the obtained image with acustom-designed app. This biosensor possesses high sensitivity (1.63 CFU/mL), short detecting time (3h), and good anti-interference performance even in real-sample testing. Overall, the developed method is expected to be a novel field detection platform for foodborne pathogens in water and food as well as for the diagnosis of infections due to its portability, ease of operation, and high feasibility.

Single layer dual hollow core antiresonant fiber based polarization beam splitters

To confront the growing challenges of integrated photonics, optical devices need to be compact in size to integrate them in communication networks where a polarization beam splitter device may play a crucial role. In this regard, hollow core antiresonant fibers have garnered significant attention as a versatile platform, for achieving efficient polarization splitting, owing to their promising characteristics. In this article, traditional and available multilayer complex cladding geometry, in dual hollow core antiresonant fiber, is simplified to single layer arrangement and created efficient polarization beam splitters device. First, we introduced a splitter with single layer cladding geometry that simultaneously presents a short device length of 2.24 cm and an ultra-wide bandwidth of 415 nm, with an extinction ratio exceeding 20 dB. This bandwidth also encompasses widely used communication wavelengths of 1.31μm and 1.55μm. Moreover, a careful investigation of geometrical dimensions, nesting, and conjoined tubes inclusion suggests that the device structure having two horizontal nested elements has an excellent splitting performance with a concise splitter length of 2.06 cm and an ultra-wide bandwidth of 465 nm, covering most telecom bands. Notably, the splitters have the highest extinction ratio of around 140 dB at 1.55μm, along with an effective single mode performance. Therefore, the claimed single layer polarization splitters might be an attractive candidate for the integration of optical devices in communication systems.

High-speed carbon nanotube photodetector based on a planarized silicon waveguide

The integration of silicon waveguides with low-dimensional materials with excellent optoelectronic properties can enable compact and highly integrated optical devices with multiple advantages for multiple fields. A carbon nanotube (CNT) photodetector integrated on the silicon waveguide has the potential to meet on-chip high-speed optical interconnection systems, based on the outstanding properties of CNTs such as picosecond-level intrinsic photoresponse time, high charge carrier mobility, broad spectral response, high absorption coefficient, and so on. However, the thermal stability of the device may be compromised due to the local suspension in the channel for the height difference between the WG and the substrate. Here, we report a low-cost and low-optical-loss method to achieve the planarized silicon waveguide. After that, the CNT photodetectors integrated on the original and planarized waveguide with asymmetric palladium (Pd)-hafnium (Hf) metal contacts are fabricated. The influence of this planarization method on the performance of devices is analyzed via comparing the dark leakage current, the leakage current rectification ratio (CRR), the series resistances (R S ), and the photoelectric response. Finally, a CNT photodetector based on the planarized waveguide with a photocurrent (Iph) ∼510.84nA, a photoresponsivity (R I ) ∼51.04mA/W, the dark current ∼0.389µA, as well as a 3 dB bandwidth ∼34GHz at the large reverse voltage −3V is shown.

End-to-end optimization of single-shot monocular metasurface camera for RGBD imaging

RGBD cameras that capture color and depth information have a wide range of applications such as robotics, autonomous driving, and cons umer electronics. Traditional RGBD imaging usually requires multi-cameras or extra active illumination which inevitably leads to bulky or complex imaging systems, hindering the growing demand for compact integrated optical devices. Optical metasurface have emerged as a powerful substitute to the traditional diffractive optical element due to the superior dispersion manipulation and extremely compact size. However, it is still a great challenge to realize a single-shot monocular metasurface camera, due to the strong and unignorable wavelength-dependent aberrations. In this work, we demonstrate an end-to-end compact single-shot monocular metasurface camera for RGBD imaging. By utilizing end-to-end joint optimization framework to learn metasurface physical structure in conjunction with deep neural networks reconstruction algorithm, the multidimensional light field information RGBD of a scene in a single shot can be reconstructed within a depth range of 0.5 m. Compared with traditional lens-based RGBD imaging, our proposed metasurface-based imaging achieves an improvement of about 2 dB in chromatic imaging and a 4 times increase in depth estimation accuracy. Our proposed scheme could facilitate the further development of the intelligent computational meta-optics in diverse fields ranging from machine vision to biomedical imaging.

Compact, remote optical waveguide magnetic field sensing using double-pass Faraday rotation-induced optical attenuation

Compact, magnetic field, B sensing is proposed and demonstrated by combining the two Faraday rotation elements and beam displacement crystals within a micro-optical fiber circulator with a fiber reflector and ferromagnets to allow high contrast attenuation in an optical fiber arm. Low optical noise sensing is measured at λ=1550nm as a change in attenuation, α, of optical light propagating through the optical noise sensing rotators and back. The circulator’s double-pass configuration, using a gold mirror as a reflector, achieves a magnetic field sensitivity s=Δα/ΔB=(0.26±0.02)dB/mT with a resolution of ΔB=0.01mT, over a detection range B=0−89mT. The circulator as a platform provides direct connectivity to the Internet, allowing remote sensing to occur. The method described here is amenable to multisensor combinations, including with other sensor technologies, particularly in future integrated waveguide Faraday optical circuits and devices, extending its utility beyond point magnetic field sensing applications.

Transmissible topological edge states based on Su-Schrieffer-Heeger photonic crystals with defect cavities.

Topological photonic crystals have great potential in the application of on-chip integrated optical communication devices. Here, we successfully construct the on-chip transmissible topological edge states using one-dimensional Su-Schrieffer-Heeger (SSH) photonic crystals with defect cavities on silicon-on-insulator slab. Different coupling strengths between the lateral modes and diagonal modes in photonic crystal defect cavities are used to construct the SSH model. Furthermore, two photonic SSH-cavity configurations, called α and β configurations, are designed to demonstrate the topological edge states. Leveraging the capabilities of photonic crystal transverse electric modes with on-chip transmission, we introduced a waveguide to excite a boundary defect cavity and found that the transmission peak of light, corresponding to the topological edge state, can be received in another boundary defect cavity, which is caused by the tunnel effect. Moreover, the position of this peak experiences a blue shift as the defect cavity size increases. Therefore, by tuning the size of the SSH defect cavity, on-chip wavelength division multiplexing function can be achieved, which is demonstrated in experiments. The ultrafast response time of one operation can be less than 20 fs. This work harmonizes the simplicity of one-dimensional SSH model with the transmissibility of two-dimensional photonic crystals, realizing transmissible on-chip zero-dimensional topological edge states. Since transmission peaks are highly sensitive to defect cavity size, this configuration can also serve as a wavelength sensor and a reconfigurable optical device, which is of substantial practical value to on-chip applications of topological photonics.

High‐Efficiency Pancharatnam–Berry Metasurface‐Based Surface Plasma Coupler

To excite surface plasmon polaritons (SPPs) in an ultrathin way, metasurface‐based SPP couplers are widely used for converting propagating waves into driven waves bounded on their surfaces. Among them, the Pancharatnam–Berry (PB) metasurface coupler has a strong ability to control spin‐polarized waves, but is still limited by its coupling efficiency. Herein, a PB metasurface‐based SPP coupler that can support efficient circular‐polarization conversion with both the transverse magnetic and transverse electric modes of the SPP is proposed. The coupler is composed of an upper transmissive PB gradient metasurface and a lower eigenmode board to transform a circularly polarized plane wave into left‐handed circularly polarized and right‐handed circularly polarized surface waves that propagate in opposite directions. In the experimental results, it is indicated that the directionality factor of the tested SPP coupler is 28.6. The proposed PB metasurface coupler may pave the way for future integrated optical devices with high efficiency and excellent polarization‐split properties.

Planar and ridge waveguides prepared by ion implantation and femtosecond laser ablation in Er3+-doped germanate glasses

The work reports the hydrogen-ion implantation and femtosecond laser ablation in the Er3+-doped germanate glass to make planar and ridge optical waveguides. The energy is 400 keV and the dose is 6 × 1016 ion/cm2 for the ion implantation. The pulse energy is 3 μJ and the scanning speed is 50 μm/s for the femtosecond laser ablation. A microscope is used to observe the cross-section morphologies of the planar and ridge waveguides. A measurement of the near-field intensity distribution at 632.8 nm is performed by the end-face coupling system. The effective refractive indices of the propagation modes are recorded by the m-line technique. It’s the first time that a ridge waveguide is fabricated in the Er3+-doped germanate glass by the proton implantation and femtosecond laser ablation, which is with potential application as new integrated optical devices.

Hybrid Silicon Nitride Photonic Integrated Circuits Covered by Single-Walled Carbon Nanotube Films.

The integration of low-dimensional materials with optical waveguides presents promising opportunities for enhancing light manipulation in passive photonic circuits. In this study, we investigate the potential of aerosol-synthesized single-walled carbon nanotube (SWCNT) films for silicon nitride photonic circuits as a basis for developing integrated optics devices. Specifically, by measuring the optical response of SWCNT-covered waveguides, we retrieve the main SWCNT film parameters, such as absorption, nonlinear refractive, and thermo-optic coefficients, and we demonstrate the enhancement of all-optical wavelength conversion and the photoresponse with a 1.2 GHz bandwidth.

High-performance plasmonic band-pass / band-stop / cut-off filter using elliptical and rectangular ring resonators

A plasmonic filter including Metal-Insulator-Metal waveguides (MIM) with an elliptical ring resonator is proposed. Using the Finite Difference Time Domain (FDTD) method, we analyze the amount of transmittance in the structure. The results show the creation of five resonance modes with narrow FWHM and suitable transmittance at the resonance points of the spectrum. The resonance wavelength and transmittance at the resonance points are tuned by changing the device geometry. In this structure, preventing the transmittance of the spectrum creates a band-gap between the wavelengths 919 nm–1388 nm, which by changing the size of the structure, the band-gap width changes. This filter also cuts off the transmission of wavelengths greater than 1707 nm. By adding a rectangular ring resonator outside the elliptical ring resonator, the performance of the device was improved and the transmittance included very narrow resonance modes. Due to the number of resonance modes and their narrow FWHM, the introduced structures can be used as devices for filtering several wavelengths, which significantly reduces costs and enhances economic efficiency for the production of plasmonic band-pass filters. Also, this structure can be used as band-stop and cut-off filters. This multiplicity of functions makes it cost-effective to use the proposed device for making integrated optics devices.

Tunable Magnetic and Optical Anisotropy in ZrO2‐Co Vertically Aligned Nanocomposites

AbstractMetamaterials have gained great research interest in recent years owing to their potential for property tunability, multifunctionality, and property coupling. As a new group of self‐assembled thin films, vertically aligned nanocomposite (VAN)‐based hybrid metamaterials have been demonstrated with significant anisotropic physical properties and a broad range of property tailorability, such as optical anisotropy, magnetic anisotropy, hyperbolic dispersion, and enhanced second harmonic generation properties. Herein, self‐assembled ZrO2‐Co nanocomposite films, with high epitaxial quality and ultra‐fine vertically aligned Co nanopillars (with an average diameter of ≈2 nm) embedded in a ZrO2 matrix, are fabricated using a pulsed laser deposition (PLD) method. The Co pillar density can be effectively tuned by varying the Co concentration in the target, which results in tunable optical properties and magnetic properties. Specifically, a high saturation magnetization of 100 emu cm−3, strong out‐of‐plane magnetic anisotropy and tailorable magnetization properties are achieved via tuning the Co nanopillar density. Coupled with hyperbolic dispersion of dielectric constant from 950 to 1500 nm in wavelength, plasmonic Co metal nanopillars, and the unique dielectric ZrO2 matrix, this new nanoscale hybrid metamaterial shows great potential for future integrated optical and magnetic device designs.

Modeling and simulation of erbium-ytterbium co-doped optical waveguide amplifiers with dual-wavelength pumping at 980 nm and 1480 nm

With the rapid development of silicon photonic chips and integrated photonic circuits, erbium-doped optical waveguide amplifiers have received more and more attention in order to compensate for the transmission and coupling losses caused by the integration of optical devices on a chip. Pumping wavelength and pumping efficiency directly affect the gain and noise figure of the amplifier. In this paper, we propose an innovative dual-wavelength pumping method based on an erbium-ytterbium co-doped optical waveguide amplifier with simultaneous pumping at 980 nm and 1480 nm. A relaxation method based on the fourth-order Range-Kutta method is used to solve the rate and propagation equations and simulate the gain characteristics of the dual-wavelength pumping method for different ytterbium-erbium ion concentration ratios, erbium ion concentrations and ratio K between the 980 nm and total pump power. From the simulation results, it can be seen that the gain of the dual-wavelength pumping method is higher than that of the single-wavelength pumping methods when the erbium ion concentration exceeds 3 × 1026 m−3. At higher erbium ion concentrations, the dual-wavelength pumping method can provide higher gain for optical waveguide amplifiers, and may be able to become a new choice of pumping method for optical waveguide amplifiers.

Generation of Vector Vortex Beams Based on the Optical Integration of Dynamic Phase and Geometric Phase

The phase and polarization of electromagnetic waves can be conveniently manipulated by the dynamic phase and geometric phase elements. Here, we propose a compact optical integration of dynamic phase and geometric phase to generate arbitrary vector vortex beams on a hybrid-order Poincaré sphere. Two different technologies have been applied to integrate dynamic and geometric phase elements into a single glass plate to modulate the phase and polarization of light simultaneously. A spiral phase structure is made on one side of a glass substrate with optical lithography and a geometric phase metasurface structure is designed on the other side by femtosecond laser writing. The vector polarization is realized by the metasurface structure, while the vortex phase is generated by the spiral phase plate. Therefore, any desirable vector vortex beams on the hybrid-order Poincaré sphere can be generated. We believe that our scheme may have potential applications in future integrated optical devices for the generation of vector vortex beams due to its the high transmission efficiency and conversion efficiency.

Systematic study of InP/InGaAsP heated plasma etching and roughness improvement for integrated optical devices

Indium Phosphide (InP) is one of the most widely commercialized III–V semiconductor materials for making efficient lasers operating in the O-band and C-band. It is also gaining significant attention as a material platform for passive integrated optical devices operating in the telecommunication wavelength range for optical communication networks and sensing. Fabrication of such devices requires a process of lithography for pattern writing followed by plasma etching for transferring the pattern into the semiconductor material. InP is one of the most difficult materials to etch due to the fact that the etching by-products (InClx) are not volatile at temperatures less than 150 °C. There have been some studies showing InP etching at lower temperatures and room temperatures. However, after carefully studying these processes using multiple plasma etching tools, we found that the claimed processes are not repeatable because of the low volatility of the by-products at room temperature. In this work, we demonstrate a systematic study of etching InP using methane-hydrogen-based chemistry at low temperatures (60 °C) and chlorine-based chemistry at high temperatures (190 °C).

Формирование периодических двухфазных структур на поверхности аморфных пленок Ge-=SUB=-2-=/SUB=-Sb-=SUB=-2-=/SUB=-Te-=SUB=-5-=/SUB=- при воздействии ультракоротких лазерных импульсов различной длительности и частоты следования

Phase change memory materials due to their high susceptibility to low-intensity light fields are extremely attractive for active microphotonics and integrated optics devices. As a result of fast phase switching, these materials change the refractive index in a wide spectral range, which has found application in information storage systems. In this work, we studied the formation of two-phase periodic structures consisting of alternating lines of amorphous and crystalline phases on the surface of thin-film Ge2Sb2Te5 phase-change memory materials exposed to ultrashort laser pulses. Periodic structures were formed at a wavelength of 1030 nm at different durations and repetition rates of light pulses. It has been established that the ordering of two-phase structures obtained at a constant energy fluence remains practically unchanged with an increase in the repetition rate from 10 kHz to 1 MHz, but a change in the pulse duration from 180 fs to 10 ps leads to a violation of the periodic structure due to the formation of extended continuously crystallized regions.

Smart Metasurface for Active and Passive Cooperative Manipulation of Electromagnetic Waves.

Integrating active and passive manipulation of electromagnetic (EM) waves has significant advantages for the caliber synthesis of microwave and optical integrated devices. In previous schemes, most reported designs focus only on active ways of manipulating self-radiating EM waves, such as antennas and lasers, or passive ways of manipulating external incident EM waves, such as lenses and photonic crystals. Here, we proposed a paradigm that integrates active and passive manipulation of EM waves in a reconfigurable way. As demonstrated, circularly polarized, linearly polarized, and elliptically polarized waves with customized beams are achieved in passive operation by merging Pancharatnam-Berry phases and dynamic phases, while the radiating EM waves with a customized gain are achieved by coupling the coding elements with the radiation structure in the active manipulation. Either active or passive manipulation is determined by the sensed signals and operating state to reduce detectability. Encouragingly, the proposed strategy will excite new sensing and communication opportunities, enabling advanced conceptions for next-generation compact EM devices.

Modal analysis of silicon-on-insulator based rib waveguide using fully vectorial finite-difference mode solver

In order to interface optical integrated devices with external sources, an understanding of the modal characteristics of the optical waveguide is essential. The finite difference approach is utilized in this work to analyse a rib waveguide based on a silicon-on-insulator platform. A silicon device layer with thickness of 220 nm and a buried oxide with thickness of 2000 nm are considered. It is important to study the modal field distribution and parameters of the waveguide. The simulation results on the behaviour of modal parameters show that both effective refractive index and group index decrease with wavelength. The effective refractive index of the guided mode increases with rib width and slab thickness. It is also observed that energy is more confined in a deeply etched waveguide than in a shallow etched waveguide. Additionally, it is noted that the effective mode area and full-width half maximum increase with rib width and slab thickness.