Hybrid Optical Device Research Articles

Polymer and Hybrid Optical Devices Manipulated by the Thermo-Optic Effect.

The thermo-optic effect is a crucial driving mechanism for optical devices. The application of the thermo-optic effect in integrated photonics has received extensive investigation, with continuous progress in the performance and fabrication processes of thermo-optic devices. Due to the high thermo-optic coefficient, polymers have become an excellent candidate for the preparation of high-performance thermo-optic devices. Firstly, this review briefly introduces the principle of the thermo-optic effect and the materials commonly used. In the third section, a brief introduction to the waveguide structure of thermo-optic devices is provided. In addition, three kinds of thermo-optic devices based on polymers, including an optical switch, a variable optical attenuator, and a temperature sensor, are reviewed. In the fourth section, the typical fabrication processes for waveguide devices based on polymers are introduced. Finally, thermo-optic devices play important roles in various applications. Nevertheless, the large-scale integrated applications of polymer-based thermo-optic devices are still worth investigating. Therefore, we propose a future direction for the development of polymers.

An efficacious hybrid interferometer based on a Vernier-like effect for dual parameter sensing

ObjectiveAn efficacious hybrid optical device based on a Vernier-like effect for dual parameter sensing is proposed. The device may find potential applications for simultaneous strain and temperature monitoring for many industries such as, environmental, biotechnology, and chemical engineering. MethodThe device configuration is composed of a Michelson interferometer (MI) cascaded with a Fabry-Perot interferometer (FPI). In the manufacturing, cascaded formation of single-mode fiber (SMF), a small segment of multi-mode fiber (MMF), double side hole fiber-1 (DSHF-1), hollow Core fiber (HCF), and an infinitely extended double side hole fiber-2 (DSHF-2) are spliced together. A series of experiment demonstrates that the proposed interferometer generates an efficacious Vernier-like effect with a slight differential factor of MI and FPI spectral interferences, and this hybrid device is fully capable of measuring strain and temperature simultaneously. ResultsThe device is easy to fabricate and is made entirely by using ordinary laboratory equipment. The device is composed of unmodified optical fibers, which guarantees the robustness of the device. The experimental demonstration shows that the maximal strain sensitivity of the device is obtained as ~8.77 pm/µε with high resolution tracing steps, whereas temperature sensitivity is achieved as ~213 pm/°C.

Rapid fabrication of sub-micron scale functional optical microstructures on the optical fiber end faces by DMD-based lithography.

The rapid development of optical fiber application systems puts forward higher requirements for the miniaturization and integration of optical fiber devices. One promising solution is to integrate diffractive optical microstructures on the end faces of optical fibers. However, rapid microfabrication on such tiny and irregular substrates is a challenge. In recent years, Femtosecond laser polymerization technology has become an effective solution to the challenge, which can be flexibly applied for the fabrication of complex 3D microstructures with ultra-high resolution. When the demand for the lithography resolution is not very high, other microfabrication methods with a lower technical threshold may be developed for achieving a balance between fabrication precision, cost and efficiency. In this paper, we report a Digital Micromirror Device (DMD) based lithography method dedicated to the fabrication of functional optical microstructures on the optical fiber end faces. Especially, it's also applicable to single-mode fibers (SMFs). By the projection via a 40x objective lens, the fabrication resolution of 0.405 μm was achieved within an exposure area of 209.92 μm × 157.44 μm. We evaluated the microfabrication results by the photomicrographs and the optical diffraction modulation effects of the functional optical microstructures. This method provides a new idea for fabricating both hybrid optical fiber devices and SMF devices, and it may be an alternative method for resolving the conflict between the precision, the cost and the efficiency.

Integration of Fluorescent, NV-Rich Nanodiamond Particles with AFM Cantilevers by Focused Ion Beam for Hybrid Optical and Micromechanical Devices

In this paper, a novel fabrication technology of atomic force microscopy (AFM) probes integrating cantilever tips with an NV-rich diamond particle is presented. Nanomanipulation techniques combined with the focused electron beam-induced deposition (FEBID) procedure were applied to position the NV-rich diamond particle on an AFM cantilever tip. Ultrasonic treatment of nanodiamond suspension was applied to reduce the size of diamond particles for proper geometry and symmetry. The fabricated AFM probes were tested utilizing measurements of the electrical resistance at highly oriented pyrolytic graphite (HOPG) and compared with a standard AFM cantilever performance. The results showed novel perspectives arising from combining the functionalities of a scanning AFM with optically detected magnetic resonance (ODMR). In particular, it offers enhanced magnetometric sensitivity and the nanometric resolution.

Vertical mode transition in hybrid lithium niobate and silicon nitride-based photonic integrated circuit structures.

This Letter presents an optical mode transition structure for use in Si3N4/LiNbO3-based hybrid photonics. A gradual modal transition from a Si3N4 waveguide to a hybrid Si3N4/LiNbO3 waveguide is achieved by etching a terrace structure into the sub-micrometer thick LiNbO3 film. The etched film is then bonded to predefined low pressure chemical vapor deposition Si3N4 waveguides. Herein we analyze hybrid optical devices both with and without the aforementioned mode transition terrace structure. Experimental and simulated results indicate that inclusion of the terrace significantly improves mode transition compared to an abrupt transition, i.e., a 1.78 dB lower mode transition loss compared to the abrupt transition. The proposed transition structure is also applied to the design of hybrid Si3N4-LiNbO3 micro-ring resonators. A high-quality factor (Q) resonator is demonstrated with the terrace transition which mitigates undesired resonances.

Hybrid light-emitting polymer/SiN_x platform for photonic integration

Organic semiconductors have potentials for a broad range of applications; however, it is difficult to be integrated with traditional inorganic material to meet the need of further application. Based on low-temperature silicon nitride (SiNx) deposition technique, here we demonstrate a hybrid structure fabricated by directly depositing high-quality SiNx on organic polymer film Poly[2-(2',5'-bis(2"-ethylhexyloxy)- phenyl) -1,4-phenylene vinylene] (BEHP-PPV). Stacked BEHP-PPV/SiNx hybrid structures with different periods are obtained and their optical properties are systematically characterized. Moreover, a group of BEHP/PPV embedded SiNx micro-disk is fabricated and amplification of spontaneous emission (ASE) is observed under optical pumping, further confirming that the gain properties of BEHP/PPV are well preserved. Our technique offers a platform to fabricate organic/inorganic hybrid optical devices compatible with integrated components.

Hybrid nanodiamond and titanium dioxide nanobeam cavity design

Titanium dioxide is an emerging optical material, with a relatively high refractive index (n ∼ 2), which allows for high confinement of the electromagnetic field. Extensive research has been conducted on the negatively charged nitrogen vacancy centre in diamond due to its robust electronic and optical properties. In particular, its stable room-temperature photoluminescence properties have been considered for quantum optical applications. Nanobeam cavities are a geometry that offer exceptionally large-Q values given their minimal footprint, a must for high density and compact optical architecture. This paper presents an ultrahigh-Q nanobeam cavity within titanium dioxide in a low-refractive index environment operating at the negatively charged nitrogen vacancy centre of diamond. This research opens the possibility of hybrid optical devices utilising titanium dioxide and diamond.

Effects of Solvents in the Fabrication of a Hybrid Optical Device Based on GaN and MEH-PPV

Effects of Solvents in the Fabrication of a Hybrid Optical Device Based on GaN and MEH-PPV

Organic/inorganic hybrid optical upconversion devices for near‐infrared imaging

AbstractTraditional near infrared (NIR) imaging is realized by a two dimensional InGaAs photodetector (PD) array integrated with a Si readout integrated circuit active matrix. The integration between the two different semiconductor arrays seriously restrains the device size‐scalability and leads to high manufacture cost. One alternative approach is to up‐convert infrared photons to a shorter wavelength (e.g., 1 µm or below) that can be effectively detected by a conventional Si detector. Herein, we report a highly simplified single‐mesa (pixel‐less) hybrid organic/inorganic up‐conversion imaging device through the integration of a large area inorganic PD with an organic light emitting diode, which can up‐convert a NIR scene to a visible‐light image. By combining the fabricated device with a commercially available camera, we demonstrate the first time pixel‐less up‐conversion NIR imaging with a spatial resolution of better than 6 µm. This device has great potential for making low‐cost, large‐area and high resolution NIR cameras (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Enhancement of two photon processes in quantum dots embedded in subwavelength metallic gratings

We show a large enhancement of two-photon absorption processes in nanocrystal quantum dots and of light upconversion efficiency from the IR to the near-IR spectral regime, using a hybrid optical device in which near-IR emitting InAs quantum dots were embedded on top a metallic nanoslit array. The resonant enhancement of these nonlinear optical processes is due to the strong local electromagnetic field enhancements inside the nanoslit array structure at the extraordinary transmission resonances. A maximal two-photon absorption enhancement of more than 20 was inferred. Different high field regions were identified for different polarizations, which can be used for designing and optimizing efficient nonlinear processes in such hybrid structures. Combining nanocrystal quantum dots with subwavelength metallic nanostructures is therefore a promising way for a range of possible nonlinear optical devices.

Cost-effective diffuse reflectance spectroscopy device for quantifying tissue absorption and scattering in vivo

A hybrid optical device that uses a multimode fiber coupled to a tunable light source for illumination and a 2.4-mm photodiode for detection in contact with the tissue surface is developed as a first step toward our goal of developing a cost-effective, miniature spectral imaging device to map tissue optical properties in vivo. This device coupled with an inverse Monte Carlo model of reflectance is demonstrated to accurately quantify tissue absorption and scattering in tissue-like turbid synthetic phantoms with a wide range of optical properties. The overall errors for quantifying the absorption and scattering coefficients are 6.0+/-5.6 and 6.1+/-4.7%, respectively. Compared with fiber-based detection, having the detector right at the tissue surface can significantly improve light collection efficiency, thus reducing the requirement for sophisticated detectors with high sensitivity, and this design can be easily expanded into a quantitative spectral imaging system for mapping tissue optical properties in vivo.

Block Copolymer Films Hierarchical Assembly in Confinement

Ultrathin block copolymer films are promising candidates for bottom-up nanotemplates in hybrid organic-inorganic electronic, optical, and magnetic devices. Key to many future applications is the long range ordering and precise placement of the phase-separated nanoscale domains. In this paper, a combined top-down/bottom-up hierarchical approach is presented on how to fabricate massive arrays of aligned nanoscale domains by means of the self-assembly of asymmetric poly (styrene-block-ethylene/butylenes-block-styrene) (SEBS) tirblock copolymers in confinement. The periodic arrays of the poly domains were orientated via the introduction of AFM micromachining technique as a tool for locally controlling the self-assembly process of triblock copolymers by the topography of the silicon nitride substrate. Using the controlled movement of 2- dimensional precision stage and the micro pressure force between the tip and the surface by computer control system, an artificial topographic pattern on the substrate can be fabricated precisely. Coupled with solvent annealing technique to direct the assembly of block copolymer, this method provides new routes for fabricating ordered nanostructure. This graphoepitaxial methodology can be exploited in hybrid hard/soft condensed matter systems for a variety of applications. Moreover, Pairing top-down and bottom-up techniques is a promising, and perhaps necessary, bridge between the parallel self-assembly of molecules and the structural control of current technology.

An integrated hybrid optical device for sensing applications

AbstractWe present the design and the fabrication of an integrated hybrid optical sensor for liquid and gas sensing based on the anodic bonding technique. The device is composed by three distinct elements separately realised and then joined together: a planar SOI waveguide, a porous silicon micro‐chamber and a glass slide. The presence of a liquid or gaseous substance in the reaction chamber is revealed as a change in the propagation characteristic of the guided mode. In case of exposure to methanol, the preliminary experimental results show that the propagation of the laser beam, coupled into the SOI waveguide, has been efficiently modulated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Talbot effect in selfoc microlens: application in manufacturing

We present a hybrid optical device for the measurement of axial refractive index and gradient parameter variations in a selfoc microlens by the Talbot effect. The intrinsic nature of the device, that combines a linear grating and an inhomogeneous medium, permits us to measure changes of the parameters as functions of the position shift of the first self-image. The potential accuracy of the measurement of these parameters is estimated.

Nanoimprinted strain-controlled elastomeric gratings for optical wavelength tuning

We demonstrate strain-controlled gratings made of an organic elastomer, polydimethylsiloxane (PDMS), which can achieve optical wavelength tuning by varying their spatial periods. The whole device structure presented in this work incorporates a nanoimprinted PDMS grating integrated with electrostatic microelectromechanical systems actuators on a silicon chip. The fabrication of the device combines polymer soft lithography, nanoimprint lithography, and silicon micromachining across multiscale dimensions ranging from a few hundred nanometers to a few millimeters. The fine tuning capability with fast dynamic response of our PDMS/silicon hybrid optical grating device makes it attractive for use in various micro-optical instruments.

Design and fabrication of a hybrid diffractive optical device for multiple-line generation over a wide angle

A new hybrid optical device that is capable of splitting a monochromatic laser beam into an arbitrary number of lines over a wide angle is presented. It consists of a binary surface-relief computer-generated phase hologram and a continuous parabolic surface-relief grating. In this device the phase hologram serves to generate three small, parallel lines while the continuous parabolic surface-relief phase grating acts as an array of diverging parabolic lenses to widen these lines. The binary surface-relief was generated into one side of a quartz substrate through a plasma-etching process, and the parabolic profile was generated into a thick photoresist deposited on the other side of the quartz substrate. Calculations showed that a diverging parabolic lens with a f-number of 0.5 would deliver the desired optical pattern of multiple beams distributed over 90 degrees . A surface-relief depth of 6.0 mum was calculated with consideration of the phase distributions of such lens. The parabolic profiles were fabricated in a 10-mum-thick photoresist, by use of a contact exposure through a mask with a space pattern of repetitive 4- and 6-mum lines. He-Ne laser light was passed through a device that generated three parallel lines over a 90 degrees angle. The resulting diffraction patterns were characterized, and a satisfying result was obtained. The resulting multiple-line pattern can be used in robot vision and other applications.

Star Products of Quartic Maps with Two Equally High Peaks

The double-well potential systems and a hybrid optical bistability device with liquid crystal have a relation to quartic maps with two equally high peaks. The star products for all doubly superstable kneading sequences in the kneading plane are presented, the generalized Feigenbaum's metric universalities such as scaling factors {αC, αD, αE} and convergent rates {δa, δη, δa,η} are obtained.

SHEDDING LIGHT ON HYBRID OPTICS: A Tutorial in Coupling

In most fiber optic systems, optical fiber and waveguides are coupled to and from bulk optical devices, creating hybrid optical devices. In this tutorial article, the authors explain in detail how to successfully collimate, focus, and align hybrid optics, including polarizing and polarization maintaining optics.

Symbolic dynamics of the sine-square map

Symbolic dynamics is developed for the sine-square map, which is related to a hybrid optical bistability device with liquid crystal as the nonlinear medium in the cavity. In particular, the skeleton of superstable orbits in the kneading plane has been constructed. Using this nontrivial example we give a systematic presentation of recent progress in applied symbolic dynamics in order to acquaint practitioners in nonlinear dynamics with this powerful tool.

Epitaxially induced secondary grain growth in Ti:LiNbO3 optical waveguides

Lithium niobate (LiNbO3) is one of the most promising materials for use in hybrid optical waveguide devices because of its high electro-optic coefficient and its availability as large single crystals. Optical waveguides in LiNbO3 are most commonly made by Ti indiffusion in which strips of Ti metal (between 10 and 100 nm thick) are deposited on a single crystal LiNbO3 substrate. The device is then heated to temperatures around 1000°C typically for 6 hours. During this time, the Ti diffuses into the LiNbO3 to form a Ti-rich LiNbO3 solid solution. This solid solution has a higher refractive index than the substrate and forms the waveguide region. Factors controlling the indiffusion process, however, are not very well understood and very little is known about the microstructural changes which occur during Ti indiffusion. In this study, the microstructure of Ti:LiNbO3 optical waveguides was examined as a function of time and temperature using transmission electron microscopy (TEM).