Planar Waveguide Structure Research Articles

Planar and ridged waveguide preparation on erbium pre-implanted fused silica by multi-energy helium ion implantation and femtosecond laser ablation

Ion implantation stands as a highly competitive technique for fabricating optical waveguide structures within photoelectric materials. In this work, both planar and ridge waveguides have been successfully realized on fused silica. The fabrication process begins with the implantation of erbium ions into fused silica, utilizing an energy of 400 keV and a fluence of 5×1015ions/cm2 to produce a fluorescence effect. Following this, helium ions are implanted at varying energies −450, 500, and 550 keV-with a consistent fluence of 3.2×1016ions/cm2 to create a planar waveguide structure. Subsequently, the ridge waveguide is meticulously prepared through the application of laser ablation, leveraging the pre-existing planar waveguide as a foundation. The guide mode of the planar waveguide is characterized at a wavelength of 632.8 nm using the prism coupling method. Additionally, the near-field light intensity distribution at the same wavelength is assessed via the end-face coupling technique and further analyzed using the finite-difference beam propagation method. To substantiate the practical utility of these waveguides, measurements of the propagation loss and fluorescence properties are conducted.

Nanoscale Kirkendall shift in thin films studied using x-ray waveguide structures

Kirkendall effect has played an important role in developing the understanding of atomic diffusion and mass transport in solids. In thin films and multilayers, in which the microstructure may be far from thermal equilibrium, behavior of a system can be very different from that of the bulk. Therefore, there is a great need to understand the peculiarities of Kirkendall shift occurring at nanometer or sub-nanometer length scale in such systems. In the present work, Kirkendall shift in thin films has been measured with sub-nanometer accuracy, by making use of x-ray planar waveguide structures. Using this technique, we report an apparently counterintuitive result of Kirkendall shift associated with self-diffusion in nanocrystalline iron. The cavity of the waveguide consists of two layers of iron having different microstructures, separated by a thin marker layer of Ag. Thermal annealing results in shift of the Ag marker towards the Fe layer having a coarser grain structure. The effect is established unambiguously by studying two samples with the order of the two Fe layers reversed, and a third sample with the two Fe layers having the same microstructure. The result can be understood in terms of the difference in the microstructure of the two Fe layers; difference in the grain size and hence different concentration of the grain boundaries in the two layers results in a net mass transfer from one region to the other.

SLOW ELECTROMAGNETIC WAVES IN PLANAR THREE-COMPONENT WAVEGUIDE STRUCTURE WITH MU-NEGATIVE METAMATERIAL

This work is devoted to study of the dispersive properties of the slow electromagnetic waves that propagate along the planar waveguide structure that consists of semi-bounded plasma region, metamaterial slab and semibounded region of ordinary dielectric. It is studied the case when all media are homogeneous and isotropic. The dispersion properties, the phase and group velocities, as well as the electromagnetic field spatial structure of the eigen TE modes are studied in the frequency range where the metamaterial possess negative permeability.

Slow Electromagnetic Surface TM-Waves in Planar Waveguide Structure with Mu-Negative Metamaterial Slab

In this work, we study the properties of slow electromagnetic surface TM-waves propagating along the planar waveguide structure involving the mu-negative metamaterial slab. The planar mu-negative metamaterial layer separates two semi-infinite regions: the plasma and the conventional dielectric. All media are assumed to be linear, homogeneous, and isotropic. The dispersion properties, the phase and group velocities, the spatial distribution of the electromagnetic fields of the TM mode in frequency range where the metamaterial has a negative permeability are under the consideration. The properties of this TM-eigenwave of the structure and two other TE modes are compared. It is studied the TM-eigenwave properties variation with metamaterail and plasma-like media properties changing. It is shown that for the considered structure, the properties of the TM mode depend significantly on the parameters of the plasma-like medium.

Bright optical spatial solitons in a photovoltaic photorefractive waveguide exhibiting the two photon photorefractive effect

We investigate for the first time, photorefractive solitons in a two photon photorefractive waveguide which also exhibits the bulk photovoltaic effect. The dynamical evolution equation of such solitons has been obtained under the paraxial ray approximation along with the Wentzel-Kramers-Brilluoin Jefferys (WKBJ) approximation. The existence curve for the solitons is derived and four distinct regions of power have been identified in the absence of waveguiding depending upon the threshold power for self trapping. Bistable states have been observed to be present. We have studied the effect of the planar waveguide and found that it enhances the self trapping nonlinearity and hence results in a reduction of the threshold power required for formation of the soliton. The propagation of the light beam is studied for various different strengths of the waveguide. A beam which would not have normally been self trapped can now become a soliton by virtue of the planar waveguide structure. Finally, we investigate the linear stability of these solitons by both, the Lyapunov method and numerical simulations.

Magnetic field sensor with Fano resonance in resonant plasmonic and planar waveguide structures

By introducing a waveguide layer into the surface plasmon resonance (SPR)-supported Kretschmann configuration, a Fano resonance (FR) sensor has been proposed and suggested for magnetic field sensing. FR with higher quality factor (Q) can be manipulated through the coupling between surface plasmon polariton (SPP) and dielectric planar waveguide (PWG) modes. The design procedures for determining and optimizing the performance of the magnetic field sensor (MFS) are elaborated through the numerical calculation with rigorous coupled wave analysis (RCWA) method. The sensor’s performance has been analyzed by considering the intensity sensitivity and figure of merit (FOM). By optimizing the structural parameters, the intensity sensitivity and FOM can reach 3002∕T and 1.68 × 104/T, respectively, which have been greatly increased compared to that obtained using the conventional SPR technique in state of-the-art sensors.

All-fibre heterogeneously-integrated frequency comb generation using silicon core fibre

Originally developed for metrology, optical frequency combs are becoming increasingly pervasive in a wider range of research topics including optical communications, spectroscopy, and radio or microwave signal processing. However, application demands in these fields can be more challenging as they require compact sources with a high tolerance to temperature variations that are capable of delivering flat comb spectra, high power per tone, narrow linewidth and high optical signal-to-noise ratio. This work reports the generation of a flat, high power frequency comb in the telecom band using a 17 mm fully-integrated silicon core fibre as a parametric mixer. Our all-fibre, cavity-free source combines the material benefits of planar waveguide structures with the advantageous properties of fibre platforms to achieve a 30 nm bandwidth comb source containing 143 tones with <3 kHz linewidth, 12 dB flatness, and >30 dB OSNR over the entire spectral region.

Magnetic Field Sensor with Fano Resonance in Resonant Plasmonic and Planar Waveguide Structures

Magnetic Field Sensor with Fano Resonance in Resonant Plasmonic and Planar Waveguide Structures

Fabrication and properties of the He+-implanted K9 glass waveguide

This work reports on the fabrication and characterization of a K9 glass planar waveguide structure. The helium ion implantation was employed to form the waveguide on the K9 glass. The choices of the energy of 0.4 MeV and the dose of [Formula: see text] ions/cm2 were conducted by the SRIM 2013. The [Formula: see text]-line spectroscopy and the modal profile of the He[Formula: see text]-irradiated K9 glass waveguide were performed by the prism-coupling system and the end-face coupling technique at 0.6328 [Formula: see text]m, which suggests the capability of light propagation. The He[Formula: see text]-implanted K9 glass waveguides can serve as potential candidates for advanced integrated optoelectronic devices.

The composite planar waveguide structure consisting of the linearly graded-index layer and the nonlinear layer formed with an increasing the electric field

The new type of the composite planar waveguide characterized by unique optical properties caused by the special selection of the waveguide layers is described. The interface between linearly graded-index layer and medium characterized by a sharp appearance of self-focusing Kerr type nonlinear response is considered. The nonlinear surface wave propagating along the interface is obtained analytically as exact solution to the wave equation with dielectric function depending on across interface coordinate and electric field. The possibility of controlling the redistribution of wave energy between layers along the waveguide with an increase in the effective refractive index and the characteristic distance of the gradient medium is shown.

Photonic metamaterial planar optical waveguide structures with all Kerr-type nonlinear guiding films

Photonic metamaterial planar optical waveguide structures with all Kerr-type nonlinear guiding films

Absorption and Self-Calibrated Sensing Based on Tunable Fano Resonance in a Grating Coupled Graphene/Waveguide Hybrid Structure

A grating coupled graphene surface plasmon and planar waveguide structure is investigated. A sharp asymmetric profile Fano resonance attributed by the coupling between the graphene plasmon and the waveguide mode can be observed. The physical origin of Fano resonance are analyzed by electric field distribution, and the tunable Fano resonances with different line profiles are demonstrated by varying the Fermi level and the incident angle. The further studies demonstrate the Fano resonance has a potential application in light absorption and the absorption can reach 76% when graphene carrier mobility is 0.5 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /(Vs). In addition, the Fano resonance could potentially be applied as a self-referenced refractive index sensor due to the decoupled property of Fano resonance and a sensitivity of 5.21 μm/RIU can be achieved. Thus, the Fano resonance we proposed in the work would have great prospects in developing excellent light absorption and refractive index sensor functional devices.

Unidirectional guided resonances in anisotropic waveguides.

We show that anisotropic planar anti-guiding waveguide structures with two radiation channels toward the surrounding cladding materials can support unidirectional guided resonances (UGRs), where radiation is canceled in one of the radiation channels and redirected into the other. Their formation is subtle as it requires breaking the so-called polar anisotropy-symmetry of the structures. Then, UGRs appear at specific wavelengths and light propagation directions, are robust, and are characterized by phase singularities in the channel in which radiation is canceled. The mechanism we describe allows for ready selection of the radiation direction, as well as tuning of the wavelength and the propagation angle at which UGRs occur.

Wavelength and intensity based lossy mode resonance breathing sensor

Copper oxide (CuO) allows the generation of lossy mode resonance (LMR) in a wide wavelength range of the optical spectrum, both in the visible and the near-infrared (NIR). For this, it is necessary to use a configuration based on the lateral incidence of light on the edge of a planar waveguide structure. On the other hand, the use of additional coatings of tin oxide (SnO2) and agarose allows an increase in the sensitivity of the sensor, in response to the breathing monitoring. The sensors were characterized, both in intensity and wavelength. In both cases their behavior depends on the position of the LMR in the optical spectrum. Therefore, it is convenient to extract the design rules that allow an optimal behavior of the sensor. In this sense, sensors located in the NIR presented a better behavior in terms of sensitivity and quality of the signal. In addition, the devices were tested in different conditions: repetitive tests at different distances, oral and nasal breathing, and breathing after doing physical exercise.

Waveguide evanescent waves based structured illumination microscopy with compact structure and flexible design

We propose a waveguide-based structured illumination microscopy (SIM) method for super-resolution surface imaging, which can exceed the 2-fold diffraction-limit improvement in traditional linear SIM by employing surface evanescent waves interference patterns. The planar waveguide structure is illuminated by grating coupled focused beams, which avoid a large adiabatic taper area and ensures a small footprint. Moreover, Blind-SIM algorithm is adopted in image reconstruction to avoid sophisticated control for the illumination field. In this designed waveguide structure, the resolution of sparse fluorescent beads improved from 246 nm to 64 nm (3.8-fold improvement) in a 5 × 5 μm2 field of view (FOV). Two beads with an 80 nm gap were resolved with a 45% dip and the resolution of diffraction-limited image of dense object was also enhanced. This method exploits a more compact waveguide structure that is easier and cheaper to fabricate, and the flexibility in design helps to improve the structure with wider FOV and higher imaging resolution.

Enhanced Raman intensity in ZnS planar and channel waveguide structures via carbon ion implantation

Planar and channel waveguides in ZnS single crystal are fabricated by 6.0 MeV C ion implantation with fluences of 5 × 1014 and 1 × 1015 ion/cm2 at room temperature. The optical modes for the planar waveguides are measured by using a prism coupler by the well-known m-line method. The near-field light intensity profiles for the planar and channel waveguides are measured by the end-face coupling setup at 633 nm and 1539 nm. The reflectivity calculation method and the finite difference beam propagation method are used to reconstruct the refractive index profile of the planar waveguides and near-field intensity distribution of planar and channel waveguides. Raman images obtained with a 532-nm laser are collected to evaluate the damage to the ZnS crystal and waveguide layers.

Er3+/Yb3+ co-doped phosphate glass waveguides formed by the H+ ion implantation

The 400 keV proton implantation with a fluence of [Formula: see text] ions/cm2 was applied on the [Formula: see text] co-doped phosphate glass to fabricate a planar waveguide structure. The mode profile at the end face of the waveguide was measured by the end-face coupling technique. The energy loss profile of the energetic protons was calculated by the SRIM 2013. The refractive index distribution was simulated by the reflectivity calculation method. Based on these results, the formation theory of the planar waveguides was discussed through simulating the energy loss distribution and analyzing the reconstructed refractive index profile, which could be used for applications in the future integrated optical systems.

SERS chip fabricated by the thermal effect in a double-metal-cladding waveguide.

Different from ordinary planar waveguide structure, we designed a double-metal-cladding waveguide (DMCW) for easier light coupling into the guiding layer from free space. In contrast to evanescent waves in a surface plasmon polariton waveguide, an oscillating wave is generated in the guiding layer. and a similar Fabry-Perot (FP) cavity can be formed by the DMCW. In past work, the FP cavity excited by the DMCW was used to study the refractive index of light, while in this work, the FP cavity is used to excite the photothermal effect of the metal substrate. It is a good connection between light and heat. The photothermal effect is investigated to promote the galvanic replacement reaction in the substrate. Although the experiment process is destructive to the DMCW structure, a surface-enhanced Raman scattering (SERS) chip is prepared on the basis of the photothermal effect in the DMCW. It shows that the DMCW can convert the energy of incident light into thermal energy, and then prepare the SERS chip. The chip has better uniformity, stronger activity, and higher sensitivity. The results demonstrate that the morphology of the SERS substrate created via the DMCW is far more elaborate than that via the surface plasmon polariton waveguide.

Electrically Controlled Non-Polarizing Optical Bandpass Filtering in Liquid Crystal Planar Waveguide

This letter proposes an electrically controlled non-polarizing optical bandpass filter based on prism coupled planar optical waveguide (POW) structure that incorporates a liquid crystal layer, which works in the electrically controlled birefringent (ECB) mode and makes the central wavelength for TM passband tunable. The measured passband of TM wave, tuned from 526 nm to 599 nm, overlaps with that of the TE wave at 582 nm under driving voltage of about 3.70 V.

Ridge waveguides in Yb3+-doped silicate glass fabricated by combination of proton implantation and femtosecond laser ablation

Ridge waveguides were fabricated in Yb3+-doped silicate glass by proton implantation combined with the femtosecond laser ablation. The Yb3+-doped silicate glass were implanted by H+ ions with the double-energy (470 keV + 500 keV) at a total dose of 3 × 1016 ions cm−2 for the formation of planar waveguides. After annealing at 260 °C, the double-line modification tracks, which provide lateral confinement of light to form ridge waveguide structures, were inscribed on the surface of sample with 3 μJ pulse laser energy, 50 μm s−1 scan speed, and 25 μm separation. The vacancy distribution of the original planar waveguide structure induced by the proton implantation was numerically calculated by the SRIM 2013. The near-field intensity distribution of the waveguide was measured by the end-face coupling system, which shows that the light can be well confined in the ridge waveguide. The micro-fluorescence features have been found well preserved in the waveguide region. This work indicates that the ridge waveguide fabricated by laser ablation assisted proton implantation in Yb3+-doped silicate glass has an important potential as an active waveguide device in optical fiber communication and all-optical communication.