Optical Channel Waveguides Research Articles

Polydimethylsiloxane multimode optical channel waveguides doped with yellow dye fabricated by microdispensing

Polydimethylsiloxane multimode optical channel waveguides doped with yellow dye fabricated by microdispensing

Analysis of optical channel waveguides composed of bianisotropic materials with a strong magnetoelectric effect using a transmission-line formulation

Optical modes in channel waveguides composed of lossy bianisotropic magnetoelectric (ME) materials have been theoretically investigated here. In this study, a semi-analytical method based on the Fourier expansion technique, a well-known transmission-line formulation, is generalized to ME materials in a general case. Using this method, the dispersion diagram, including both phase and attenuation constants, and the field profile of the guided modes in channel waveguides such as rib waveguides are obtained. The presence of ME materials changes the polarization of guided modes in the structure. In all stages of the analysis, the numerical results are calculated and compared with those generated by commercial electromagnetic solvers to verify the computational efficiency and accuracy of the proposed method.

EXPERIMENTAL EVALUATION OF THE HOMOGENEITY OF THE OUTPUT STREAMS OF OPTICAL RADIATION OF A RECTANGULAR SHAPE FOR VARIOUS VERSIONS OF THE OUTPUT SECTIONS OF THE LIGHT GUIDE NOZZLES FOR MEDICAL LASER EQUIPMENT

The article presents the results of a study of the homogeneity of rectangular optical radiation fluxes for different versions of the initial sections of the light guide nozzles. When conducting a significant part of laser exposure in medicine, pathological areas of biological tissue or their projections located on the surface of the body are covered with light spots with contours, as a rule, in the form of flat geometric shapes.
 The variability of the implementation of light spots in shape (circle, square, rectangle, triangle, rhombus, etc.) and linear dimensions of the cross section allows you to select the shape and size of the light spot, covering a specific pathological surface with minimal capture of intact tissues. At the same time, regardless of the shape and linear dimensions, the light spots should be as uniform as possible. To date, of particular interest is the provision of optical uniformity of rectangular light spots.
 Firstly, similar forms of spots are widely used under the influence of laser medicine. Secondly, in the original optical stages of laser equipment and the light guides connected to them, first of all, optical fibers of a cylindrical shape with a rounded cross section of the optical flow at the output are used. The purpose of this work is to optimize the parameters of light guide nozzles of medical laser equipment with rectangular output optical radiation fluxes by evaluating the uniformity of the power density distribution for various options for the output sections of the nozzles. In the work, optical flows at the output of three versions of the distal sections of light guides were studied. The light guides were formed by optical fibers, including the use of microlenses at the output ends, and were apertured by channel optical waveguides in the form of rectangular parallelepipeds.
 The experimental results obtained at the stage of physical modeling show the promise of using spherical micro-optical elements at the initial ends of optical fibers in combination with rectangular apertures in the form of channel optical waves to obtain rectangular light spots with a high level of optical homogeneity.

Bending Loss Analysis of Chalcogenide Glass Channel Waveguides for Mid-Infrared Astrophotonic Devices

In this study, the bending losses of chalcogenide glass channel optical waveguides consisting of an As2Se3 core and an As2S3 lower cladding layer were numerically evaluated across the astronomical N-band, which is the mid-infrared spectral range between the 8 µm and 12 µm wavelengths. The results reveal the design rules for bent waveguides in mid-infrared astrophotonic devices.

Meshless optical mode solving using scalable deep deconvolutional neural network

Optical mode solving is of paramount importance in photonic design and discovery. In this paper we propose a deep deconvolutional neural network architecture for a meshless, and resolution scalable optical mode calculations. The solution is arbitrary in wavelengths and applicable for a wide range of photonic materials and dimensions. The deconvolutional model consists of two stages: the first stage projects the photonic geometrical parameters to a vector in a higher dimensional space, and the second stage deconvolves the vector into a mode image with the help of scaling blocks. Scaling block can be added or subtracted as per desired resolution in the final mode image, and it can be effectively trained using a transfer learning approach. Being a deep learning model, it is light, portable, and capable of rapidly disseminating edge computing ready solutions. Without the loss of generality, we illustrate the method for an optical channel waveguide, and readily generalizable for wide range photonic components including photonic crystals, optical cavities and metasurfaces.

Direct Writing of Channel Optical Waveguides in Er3+-Doped Aluminosilicate Glass by Low Repetition Rate Femtosecond Laser

Direct Writing of Channel Optical Waveguides in Er³⁺-Doped Aluminosilicate Glass by Low Repetition Rate Femtosecond Laser

Computer vision-based method of pre-alignment of a channel optical waveguide and a lensed fiber

The work is devoted to a technique of pre-alignment of a lensed fiber and a channel waveguide of a photonic integrated circuit using computer vision methods. The design and main units of a machine vision system with illumination of the adjusted objects in reflected light are described. The technique includes detection of the spatial position of the end face of the photonic integrated circuit, fixed at an angle of 90 ± 1° to the horizontal axis of the frame, detection of the coordinates of the end face of the lensed fiber, and the subsequent correction of the position of the lensed fiber using a manipulator system. We propose a method of searching and selecting a single line corresponding to the end face of a photonic integrated circuit using a Hough transform; methods for grouping discontinuous contours of the lensed fiber and true contour determination. These methods are based on a priori knowledge of the lens geometry. Also, we describe options for suppressing noise and overcoming various defects in images. It has been shown experimentally that the error of angle determination of a lensed fiber depends on the distance between the lens and the end face of the photonic integrated circuit. The presented technique makes it possible to determine the longitudinal and angular displacements between the fiber lens and the end face of the photonic integrated circuit with errors less than 4 μm and 0.05°, respectively.

Controllable Dynamic Single‐ and Dual‐Channel Graphene Q‐Switching in a Beam‐Splitter‐Type Channel Waveguide Laser

AbstractDirect inscription of structures by femtosecond‐laser pulses facilitates the flexible fabrication of diverse optical channel waveguides in dielectric laser gain media. Among them, beam‐splitter‐type waveguide lasers have been recently studied; however, there is a lack of investigations on the effect of unique characteristics of such waveguides, such as controlled splitting ratios of output powers and selectable excitation of individual channels, for pulsed laser operation. Here, dynamic single‐ and dual‐channel graphene Q‐switching of an Yb:YAG waveguide consisting of one input and two output channels is demonstrated by controlling the power‐splitting ratio. Single‐channel Q‐switched operation, exhibiting typical Q‐switched pulses, is achieved by interaction between the graphene saturable absorber and the desired one of the two channels. When both channels exceed the Q‐switching threshold, dual‐channel Q‐switching generates a pulse train that simultaneously combines the separately Q‐switched pulses induced from each channel under excitation with a single pump source. At a fixed power‐splitting ratio, the pulsed mode can be dynamically switched between the single‐ and dual‐channel Q‐switched operations by varying the pump power. The beam‐splitter‐type waveguide laser demonstrated in this study can be further developed for multiple‐channel Q‐switching, high‐repetition‐rate mode‐locking, and on‐chip dual‐comb sources advantageous for diverse applications in optical communication, metrology, and sensing.

Direct Laser Writing and Investigation of Optofluidic Elements inside Nanoporous Silicate Matrix

The paper demonstrates direct laser writing by femtosecond laser pulses (λ = 1030 nm, tau = 220 fs, v = 200 kHz) of functional optofluidic elements inside a nanoporous silicate matrix (NPSM). The influence of focused laser pulses led to the compaction of the nanoporous frame, which made it possible to fabricate barriers for the isolation of nanoporous cells and channel optical waveguides. The writing of microchannels in the mode of decompression of a nanoporous matrix with subsequent purification of debris area in distilled water under the action of ultrasound is also demonstrated. For each type of elements, the dependences of geometric characteristics on the energy parameters of laser radiation are established. The methods of testing the elements were also developed --- checking the permeability of the barrier, the entering of laser radiation into channel waveguides. Keywords: Direct laser writing, femtosecond laser pulses, barriers, waveguide, microchannel, porous silicate matrix, nanopores.

Прямая лазерная запись и исследование оптофлюидных элементов внутри нанопористой силикатной матрицы

The paper demonstrates direct laser writing by femtosecond laser pulses (λ = 1030 nm, τ = 220 fs, v = 200 kHz) of functional optofluidic elements inside a nanoporous silicate matrix (NPSM). The influence of focused laser pulses led to the compaction of the nanoporous frame, which made it possible to fabricate barriers for the isolation of nanoporous cells and channel optical waveguides. The writing of microchannels in the mode of decompression of a nanoporous matrix with subsequent purification of area of debris in distilled water under the action of ultrasound is also demonstrated. For each type of elements, the dependences of geometric characteristics on the energy parameters of laser radiation are established. The methods of testing the elements were also developed - checking the permeability of the barrier, the entering of laser radiation into channel waveguides.

Circular large core optical elastomer waveguides fabricated by using direct microdispense fabrication method

The direct microdispensing method used for the fabrication of the optical polymer waveguides was demonstrated. The applied method allowed fabricated optical channel waveguides with circular shapes. Optical polydimethylsiloxane elastomers used for the core and cladding layer allowed fabricated optical flexible waveguides with high temperature and chemical stability. The dimensions of the waveguides were optimized for the dimension of the optical fiber with a core diameter of 500 µm. The applied materials allowed transmitted light for visible and near-infrared spectrums. The average values of the optical losses were lower than − 0.42 dB/cm at 650 nm, − 0.40 dB/cm at 850 nm, − 0.5 dB/cm at 1300 nm and − 2.06 dB/cm at 1550 nm.

Specific features of the formation of optical waveguides, contact pads and electrical interconnections on lithium tantalate substrates

The article considers the formation of titanium channel optical waveguides in LiTaO3 substrates. These structures were obtained by dry etching of grooves in SF6 plasma and magnetron sputtering of titanium film. After that, waveguides were formed by plasma etching using photoresist as mask. Technological features and modes of microstructure production are described. Al contact pads were produced by magnetron sputtering thin metal films on LiTaO3. Aluminum wires were ultrasonically bonded to Al contact pads using Delvotec 5630. The developed technology of formation of contact pads and bonding modes made it possible to obtain a bonded joint with a bond strength of 23-25 Gs.

An Experimental Technique for Aligning a Channel Optical Waveguide with an Optical Fiber Based on Reflections from the Far End of the Waveguide

An Experimental Technique for Aligning a Channel Optical Waveguide with an Optical Fiber Based on Reflections from the Far End of the Waveguide

Optical Polymer Waveguides Fabricated by Roll-to-Plate Nanoimprinting Technique

The paper reports on the properties of UV-curable inorganic-organic hybrid polymer multimode optical channel waveguides fabricated by roll-to-plate (R2P) nanoimprinting. We measured transmission spectra, refractive indices of the applied polymer materials, and optimized the R2P fabrication process. Optical losses of the waveguides were measured by the cut-back method at wavelengths of 532, 650, 850, 1310, and 1550 nm. The lowest optical losses were measured at 850 nm and the lowest average value was 0.19 dB/cm, and optical losses at 1310 nm were 0.42 dB/cm and 0.25 dB/cm at 650 nm respectively. The study has demonstrated that nanoimprinting has great potential for the implementation of optical polymer waveguides not only for optical interconnection applications.

Near-infrared lasing and tunable upconversion from femtosecond laser inscribed Nd,Gd:CaF2 waveguides

Optical channel waveguides with depressed cladding configurations have been produced in Nd,Gd:CaF2 laser crystals by using ultrafast laser inscription. Waveguide properties are investigated in terms of guiding behaviors and localized laser-induced lattice damages. Under an optical pump of 808 nm light, continuous-wave waveguide lasing at 1.06 µm is achieved, with a single-mode operation and a minimum lasing threshold of 98.8 mW. Furthermore, the visible emissions of Nd3+ with short wavelengths ranging from 415 nm to 550 nm and long wavelengths from 550 nm to 625 nm are observed upon 808 nm laser excitation via the up-converted process. The intensity ratios of two wavelength ranges are proved to be tunable through changing the pumping polarizations.

Thermal poling of glasses to fabricate masks for ion exchange

It has been demonstrated that thermally poled regions of silicate glasses are capable of blocking penetration of silver ions into the glasses in the course of ion exchange processing. This allows using locally poled regions of the glass surface as thick dielectric masks in the formation of ion exchanged structures, like channel optical waveguides, in glass substrates. This approach provides easy multiplication of the structures and, being based on the thermal electric field imprinting of the masks, allows avoiding both lithography with the use of liquid chemicals and the influence of metal masks on the spatial distribution of the ions penetrating the glass in the ion exchange.

Effects of gamma rays on elastomer multimode optical channel waveguides

The paper reports on properties of the elastomer multimode optical channel waveguides. The waveguides were fabricated by the doctor blade technique using the nickel mold with the dimension of the core 50 × 50 µm2 and irradiated by gamma rays from 60Co source with the dose rate 1 kGy/h. The applied irradiations were 14.6 kGy and 33.9 kGy and we studied the influence of gamma rays on the properties of the elastomer waveguides. We measured transmission spectra, refractive indices and the waveguide propagation losses. The lowest values of the optical losses were 0.21 dB/cm at 1310 nm and 0.35 dB/cm at 850 nm in the samples irradiated with dose 14.6 kGy and 0.55 dB/cm at 1310 nm and 0.66 dB/cm at 850 nm for the sample irradiated with a higher dose 33.9 kGy. The average value of the optical losses at 650 nm was 0.78 dB/cm (dose 14.6 kGy) and 1.05 dB/cm (dose 33.9 kGy). Optical silicone elastomers have unique properties and can be used for the realization of the optical waveguides for interconnection or realization photonics structures for applications in extreme environments.

Universal deep learning representation of effective refractive index for photonics channel waveguides

An optical waveguide is the fundamental element in a photonic integrated circuit. This paper establishes a universal deep learning representation for the effective refractive index of an optical channel waveguide for the entire and usual parameter space for applications in photonics. The deep learning model is able to make precise predictions for wide spectrum optical wavelengths, dielectric materials of refractive indices varying from 1.45 to 3.8, and a wide range of feasible geometrical parameters of the waveguides. The deep learning model consists of fully connected feedforward neural networks, and rigorous optimization of neural network architecture is carried out. Deep learning models with two and three hidden layers provide rapid convergence with a minimal number of training data points and offer unprecedented precisions that are a few orders better in magnitude than the conventional interpolation techniques.

All-Optical Humidity Sensor Using SnO2 Nanoparticle Drop Coated on Straight Channel Optical Waveguide

The straight channel optical waveguide coated with the SnO2 nanoparticle is studied as an all-optical humidity sensor. The proposed sensor shows that the transmission loss of the waveguide increases with increasing relative humidity (RH) from 56% to 90% with very good repeatability. The sensitivity to changes in relative humidity is ∼2 dB/% RH. The response time of the humidity sensor is 2.5 s, and the recovery time is 3.5 s. The response to humidity can be divided into 3 different regions, which are correlated to the degree of water adsorption in the SnO2 nanoparticle layer. Compared with the previous all-optical humidity sensor based on SnO2, the proposed sensor exhibits more rapid response, simpler fabrication process, and higher sensitivity. The proposed sensor has a potential application in the long distance, remote agriculture, and biological humidity sensing.

Optically Induced Channel Waveguide Structures with Spatial Modulation of Parameters in the Surface Layer of Lithium Niobate

Results of experimental studies of channel optical waveguide structures with spatially-modulated parameters obtained by point-by-point inducing of refractive index perturbations upon exposure to laser radiation of visible range in Y-cut LiNbO3 samples with photorefractive surface layer are presented.