Embossable grating couplers for planar evanescent wave sensors

Abstract

The paper presents input grating couplers to be applied in planar evanescent wave sensors. Waveguide films SiO2:TiO2 were obtained using the sol-gel method, and grating couplers with a groove density of 1000 g/mm and 2400 g/mm were produced using the method of master grating embossing in sol film. The influence of refractive index of the cover on incoupling angles was presented. Basing on the experimental results, detection limits involving the changes of effective indexes and refractive indexes of the cover for the investigated planar structures were determined. Sensor structures with the couplers having a groove density of 1000 g/mm enable to detect minimum changes of the effective index below 3.3×10−7 and to detect minimum changes of refractive index of the cover below 2.3×10−6. Detection limits for the structures with couplers having the groove density of 2400 g/mm are over twofold higher.

Photonic structures with grating couplers based on ZnO

“…In the case of the latter, good sensor sensitivity is achieved in structures characterized by a high sensitivity on changes of external conditions of a light on the values of effective refractive index. Also on sensor properties decide narrow angular characteristics of the optical excitation of the struc− tures as well as narrow spectral characteristics of light cou− pling by means of the grating couplers [13]. It ought to be kept in mind that the basis of realizing photonic structures with grating couplers as systems of introducing and emitting optical power into and out of the structure is the existence of waveguide layers with a relatively low attenuation of the optical signal.…”

Measurement of the maximum value of non-uniform strain using a temperature-insensitive fibre Bragg grating method

“…Many studies have been published demonstrating the promising properties of periodic structures [4]. Various methods of constructing these periodic structures have been studied, including the use of grating couplers on planar waveguides [5,6] and the sol−gel method [7]. A diffusion model was also considered for recording diffraction gratings in polymer dis− persed liquid crystal media [8].…”

Nano-sized blue spectral shift in sol–gel derived mesoporous titania films

“…It is of interest for use as gas sensor [1, 2], photoinduced optical operated materials [3], solar cell [4][5][6], photocatalyst [7][8][9], selfcleaning glasses [10], electrochromic films [11], antireflection coatings [12] and transparent conductors [13]. Titanium dioxide is also a principal component used in planar waveguide technology [14,15]. Several synthesis methods concerning titanium dioxide thin films are described in the literature, such as e-beam evaporation [2], magnetron sputtering [7,16], ultrasonic spray pyrolysis [17], chemical vapor deposition [18,19], metal organic chemical vapor deposition [13], pulsed laser deposition [20], and sol-gel method [1, 5,6,[9][10][11][12][13].…”