Method of spectroscopy m-line is an accurate method for determination of the optical parameters of the planar and stripe
waveguides. In this method, the laser beam is coupled to the waveguide (e.g. by the prism) in the form of discrete angles.
If the layer of the solid or liquid material is deposited on the waveguide, the change in the coupling angle is observed.
Modified method of the m-line spectroscopy allows for determination of the optical parameters of deposited layers with
high accuracy. Moreover, modification of the waveguide structure obtained via deposition of consecutive layers and
changes the ability to propagate not only in the same waveguide.
Modified method of m-line spectroscopy has found many potential applications in various areas such as: technological
control of the applied layers quality; modification of the light propagation in the waveguide structures; utilization in the
preventive medicine for diabetic diseases; food-control of the level of nutrients in vegetables (e.g. sugar level in white
beets).
Parameters of a waveguide may be investigated with great resolution by using the m-line spectroscopy method. By depositing successive layers on the waveguide the propagation conditions of the structure may be changed. In this paper investigations of multilayer waveguide structures by the generalized m-line spectroscopy method have been presented.
Multilayer waveguide structure is constructed by depositing successive layers on gradient index waveguide performed in glass by the ion-exchange method. The depositing layers are optimally selected in order to estimate their refractive indices, thicknesses and other parameters.
The presence of thin cover layer on planar waveguide influences its propagation characteristics. A generalized m-line
spectroscopy method enables the evaluation of the parameters (the refractive index, n and the thickness, t) of the subguiding
layers deposited on a planar waveguide. In this paper algorithm for determination of the parameters of the thin
layer (deposited on waveguide with previously evaluated index profile by m-line method) has been presented.
In the paper investigation of properties of liquid layers by using the m-line spectroscopy method has been presented. This method is generally used for investigation of thin solid layers. The layers are usually deposited by evaporating, diffusion or otherwise. Liquid layers have specific character and make possible dynamical change of some of their properties. Especially waveguide layers of liquid crystal can change their physical properties due to their anisotropy. Possibility of obtaining the great power density of light beam in thin planar waveguide in association with great resistance of isotropic layers provides an interesting opportunity to use it in practice.
In this paper study of properties of isotropic and anisotropic compounds by m-line spectroscopy method as well as their dispersion with good accuracy has been presented.
Investigation of liquid thin layers deposited on multimodal waveguide with gradient - index profile has been presented. Properties of the layers have been studied by the generalized m-line spectroscopy method. Deposited on the planar waveguide thin liquid layers have been investigated on the range refractive index 1.0002 - 1.5300. The profile of refractive index of waveguide has not been deformed because of depositing of the thin layer. Depositing of the thin layer on multimodal planar waveguide has caused the change of coupling angle to the waveguide but proportionately to successive modes of the waveguide structure. This study will be helpful to determine, for instance, illness changes of diabetic patients (sugar level in blood).
Non-chemical method of detection of sugar concentration in biological (animal and plant source) liquids has been investigated. Simplified set was build to show the easy way of carrying out the survey and to make easy to gather multiple measurements for error detecting and statistics. Method is suggested as easy and cheap alternative for chemical methods of measuring sugar concentration, but needing a lot effort to be made precise.
Determination of planar waveguide parameters with a deposited thin layer such as a refractive index and thickness by the method of m-line spectroscopy is possible. Application of the method to determination of thin film parameters of anisotropy material has been presented in this paper. Depositing of a very small quantity of the material on the planar waveguide changes propagation depending on a texture of a crystal. Liquid crystal (LC) is typical material characterizing the texture. Optical parameters of anisotropic materials (LC) have been determined by the modified m-line spectroscopy in four-layer waveguide structures. Preliminary investigation of application of this method to the study of anisotropic materials has been confirmed.
A generalized m-line spectroscopy method enables evaluation of the parameters (the refractive index, n and the thickness, W) of sub-guiding films deposited on a planar waveguide. A sub-guiding film (not reaching the guiding effect) when deposited on the existing planar waveguide influences the present guiding system and affects its guiding properties. In the method a laser beam is coupling via a prism to the sample and a light distribution decoupled by the same prism is studied. Complementary to the beam spot reflected geometrically from the prism base the light distribution takes a form of discrete lines, m-modes. This image is observed but only for some discrete values of the coupling angles. The refractive index, n and thickness, W of the waveguide are then calculated by numerical evaluation of the dispersion equation with a set of the coupling angles. From the previous and actual coupling angles the thin film parameters can be evaluated. In the paper an application of the generalized m-line spectroscopy method to biological samples is presented. Some initial measurements reveal an effect of the presence of the films on the coupling angles of the structure. The presence of glucose has been revealed in secretions of patients suffering from diabetes. Testing of glucose presence with the proposed method is performed with a trace amount of the patient secretion alike in medical preliminary tests.
M-line spectroscopy is widely used to determine parameters of planar waveguides. This paper shows a possibility to determine parameters of biological samples deposited on these waveguides. Deposition of a very small quantity of the material on the planar waveguide causes the change of light propagation. By means of m-line spectroscopy method adapted to investigations of four-layer structures it is possible to determine the parameters of biological samples.
Propagation of the light in a waveguide structure may be easily disturbed by the change of a cover. In this study multilayers of 7-octenylotrichlorosilane have been investigated as cover films. The multilayer films were deposited on the planar waveguide by self-assembly, followed by a UV illumination and repeated self-assembly processes. A growth control of the deposited films was performed by the generalized method of an m-line spectroscopy. M-line spectroscopy is one of the most sensitive methods of investigations of the cover materials parameters.
In the paper an application ofthe generalized rn-line spectroscopy to test of biological samples is presented. A generalized rn-line spectroscopy enables an evaluation ofthe parameters (the refractive index, n and the thickness, d) of sub-guiding films deposited on a planar waveguide. Examined layer ofbiological liquid between planar waveguide and prism changes the angular and intensity distribution of rn-line structure of outgoing beam. Some initial measurements reveal an effect of the presence of the films on the coupling angles of the structures. The method is noninvasive and for measurements merely small amount of substance as a drop of tiers or sweat can be used.
A generalized m-line spectroscopy enables an evaluation of the parameters (the refractive index, n and the thickness, W) of sub-guiding films deposited on a planar waveguide. The method is based on a coupling of a laser beam with a prism coupler and studying of light distribution of the beam decoupled by the same prism. Additionally to the beam spot reflected geometrically from the prism base the light distribution takes a form of discrete lines - m-modes. This image can be observed but only for some discrete values of the coupling angles. The refractive index, n and thickness, W of the waveguide are evaluated by the numerical solution of the dispersion equation with a set of the coupling angles. A sub-guiding film (not reaching the guiding effect) when deposited on the existing planar waveguide influences the present guiding system and effects its guiding properties. From the previous and actual coupling angles the thin film parameters can be evaluated. In the paper an application of the generalized m-line spectroscopy to biological samples is presented. Some initial measurements reveal an effect of the presence of the films on the coupling angles of the structures. The presence of glucose has been revealed in secretions of patients suffering diabetes. Testing of its presence with proposed method can be performed with a trace amount of the patient secretion.
Using the method of m-line spectroscopy [1] it is possible to determine parameters (thickness and refractive index) of thin films deposited on planar waveguides through indirect measurement of changes of coupling angle to the waveguide. The subject of the study were thin organic films deposited on waveguides by casting diluted polymerizable solutions, and by spin-coating thin polyimide films. These films are developed as active coatings in waveguide sensors. Numerical calculations (applied for three-layer structures) after modification to a four-layer structure allows for determining the parameters ofthin films.
The structures under study are thin polymer layers deposited on planar waveguides. Such coatings are generally used within waveguide sensors. Because of the low refractive index and sub-waveguide thickness they cannot guide the light, but they influence the modal propagation of light when deposited on the planar waveguide. Measurement of the coupling angles to these structures for different wavelengths yields values of the effective indices to the two dispersion equations with two unknowns and results in evaluation of parameters of the structure.
The temperature influence on salinity measurement by optical fiber salinity sensor has been investigated. Study of the sensor sensitivity with temperature change in range of temperatures 20 - 80 degree(s)C is presented. The construction of the sensor has followed the example of differential refractometer. As a result of this construction and high sensitivity of sensor on salinity, temperature changes have not deformed salinity measurements with the use of this sensor.
The modification of salinity sensor was achieved in such a way that it is possible to perform salinity measurement and directly to send the data about an exceeding of salinity level for the purpose of quick intervention permitted by National Environmental Standards. The designed system of a network of central controllable sensors may be useful to automatic monitoring of an environment.
Fabrication of the single modal channel waveguides in lithium niobate with a large waveguide-substrate index difference meets technological and material difficulties. It has been proved during our experimental work that because of the photolithography limitations low index increase in the channel region resulting in monomodal waveguiding needs more sophisticated technology. The waveguiding effect arises in the processed region in an annealing carefully performed after proton exchange. The precise control of redistribution of the dopant is realized by m-line spectroscopy of the processed area at the wavelength (lambda) ' < (lambda) op-operation wavelength. The method of precise control of waveguiding properties at (lambda) ' is especially useful for manufacturing of the optical switches aimed at the wavelengths of the transmission bands of long-distance communication fibers.
In optical planar and/or channel waveuides, determination of two
parameters such as: the depth and the waveguide index with the use of the
rn-line spectroscopy (prism coupling method) involves measuring of at least two
coupling angles of the guiding modes.
Most of integrated optical devices operate in sigle-mode regime but such
devices developed for 2-nd and 3-rd transmission windows are multimodal within
the VIS range thus the conventional rn-line study with the use of the He-Ne
laser yields in evaluation of the waveguide parameters under examination.
However, the conventional m-line procedure of the determination of the
waveuide parameters fails for single-mode structures developed for the
application within the VIS-range.
A method presented in the paper involves an additional two-beam
interferometric examination of the slab with a waveguiding structure. The
interference of the beams reflected from the upper and lower surfaces of the
slab results in a fringe pattern. Within the region of the waveguide boundary
one observes the fringe shift related to the difference of optical paths of
the beams in- and outside of the waveguide. The microscopic study of that
fringe pattern results in an additional relation of the waveguide depth and
its index. A substitution of the waveguide depth by the last relation results
in a modified modal eqaution for the waveguide index that can be solved by
conventional numerical methods.
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