Tigran K. Dadalyan

• PhD
• LC R&D Engineer at Azalea Vision

Point-by-point femtosecond laser writing of filaments was used to open high aspect ratio nano-holes transversely through the core of a single-mode telecommunication fiber (SMF-28). On infiltration with nematic liquid crystal, the small 200 nm diameter holes induced strong capillary alignment to facilitate strong birefringence responses when the fil...

Femtosecond laser filaments are formed by surface aberration to open nano‐hole arrays, passing through the silica cladding and guiding core cross‐section of a standard telecommunication fiber. The hollow filament grating presents a strong capillarity effect to draw nematic liquid crystal (NLC) into homogeneous alignment with the cylindrical walls a...

Nematic liquid crystal was introduced into a nano-hole array grating formed by femtosecond laser filaments in a telecommunication fiber. Capillary alignment has resulted in a strong polarization extinction ratio within a broad Bragg resonance.

We have fabricated a parallel slab of nematic liquid crystal with hybrid alignment that provides “longitudinal” gradient of refractive index for the extraordinary polarized beam. This in turn generates continuously changing angular separation between ordinary and extraordinary beams while propagating inside the slab, like the optical mirage effect....

Wavelength-dependent polarization state of light carries crucial information about light–matter interactions. However, its measurement is limited to bulky, high energy-consuming devices, which prohibits many modern, portable applications. Here, we propose and demonstrate a chip-scale spectropolarimeter implemented using a complementary metal oxide...

Wavelength-dependent polarization state of light carries crucial information about light-matter interactions. However, its measurement is limited to bulky, energy-consuming devices, which prohibits many modern, portable applications. Here, we propose and demonstrate a chip-scale spectropolarimeter implemented using a CMOS-compatible silicon photoni...

The influence of an external electric field on refractive indices of ordinary and extraordinary waves is investigated by means of the method of X-ray interferometry. The decrements of E7 type nematic liquid crystal were calculated for different values of external electric field strength and it was established that with increasing electric field str...

Simultaneous co-propagation of red nondiffracting Bessel beam and green Gaussian beam at milliwatt powers in a photosensitive azobenzene liquid crystal has been studied. The fine displacement of the narrow-width Gaussian beam relative to the Bessel beam central maximum showed the Bessel beam distortion and controlled bending of its core in the dire...

Natural liquids can contain self-aligned molecules (such as liquid crystals and biological membranes) which give them unique properties of anisotropic diffusion, coupling between the molecular orientation and flow, etc. Here, we describe the observation of new phenomena in those materials: long-distance transport and molecular orientation waves tha...

Lasing in dye-doped chiral nematic liquid crystal can be realized with low pump energy and relatively high efficiency, thanks to the high reflectivity of the periodic structure. When the helical axis is oriented perpendicular to the substrates, the main lasing peak is normal to the substrates. In some cases, ring lasing of a particular wavelength i...

The dynamics of the direct volume expansion mechanism of light-induced hydrodynamic motions in hybrid-oriented nematic liquid crystal (NLC) have been studied experimentally. It was shown that heating caused by the absorption of a laser beam results in expansion of a NLC volume and induces hydrodynamic flow in a planar capillary. The hydrodynamic fl...

A refractive Bessel lattice with micrometric periodicity is induced optically in a photosensitive azobenzene liquid crystal cell of 3 µm thickness by a green 532 nm, 30 mW Bessel beam and with simultaneous illumination by a red 632.8 nm, 15 mW Gaussian beam. The uninterrupted action of both beams plays a key role in the complete mechanism of the re...

We report the first experimental realization of spatial soliton formation by the Gaussian beam at 632.8 nm in the azobenzene liquid crystal (LC) layer with planar orientation of LC director. By appropriate anti-parallel rubbing of alignment layers on the upper and lower substrates of the cell LC molecules were oriented along the glass substrates ne...

The influence of the pump laser beam on the lasing spectral characteristics in dye-doped cholesteric liquid crystal is investigated. Under the influence of the pump laser pulses with different repetition rates and energies, non-linear reorientation and light-induced flow reorientation of chiral nematic liquid crystals (CLC) molecules was observed....

ABSTRACT A refractive Bessel lattice with micrometric periodicity is induced optically in a photosensitive azobenzene liquid crystal cell of 3μm thickness by a green 532 nm, 30mW Bessel beam and with simultaneous illumination by a red 632.8 nm, 15mW Gaussian beam. The uninterrupted action of both beams plays a key role in the complete mechanism of...

The influence of external electric field on the anisotropy of a layer of nematic liquid crystal (NLC) was investigated by means of X-Ray interferometric method. It was shown that in Xray range of the spectrum NLC E7 is a positive anisotropic medium. The decrements of a layer of NLC subjected to the electric field were calculated. As a result of reo...

The refractive index of nematic liquid crystal (NLC) E7 in the X-ray spectral range using the X-ray interferometric method, was measured experimentally. It was shown that NLC E7 is anisotropic medium for X-rays. This method is sensitive to reorientation of the molecules of liquid crystals and allows to measure the refractive index of homogeneously...

The influence of hydrodynamic flow on the lasing wavelength and stability of the laser emission average power of a dye-doped chiral liquid crystalline (DDCLC) structure is studied. Multiple lasing peaks at equidistant wavelengths are observed, which are originating from multiple domains that are induced by the hydrodynamic flow of the DDCLC. A simu...

Azimuthally modulated higher order rotationally symmetric Bessel-like optical patterns were generated by coherent superposition of two co-propagating Bessel beams – either in or out of phase. By changing the distance between the beam centers, a whole variety of transition states can be realized. As one prominent example, a 4-fold symmetry quadrupol...

In the present work the X-ray optical anisotropy of 5CB type liquid crystals has been investigated based on the method of X-ray interferometry. In this way Moire fringes have been obtained both in the absence and presence of specimens with different orientations of optical axes. The relative displacement of Moire fringes enabled us to observe and i...

Two regions of selective light reflection (in the short- and long- wavelength parts of the visible spectrum) from a thin film of a cholesteric liquid crystal (CLC), consisting of the mixture of two CLCs with opposite chirality and a nematic liquid crystal, are experimentally found for the first time. The spectral position of the reflection regions...

Influence of boundary conditions on optical properties of a layer of cholesteric liquid crystal (CLC) has been investigated. In particular, a sample was obtained which is transparent for circularly polarized light incident from one side and gives losses in the transmission spectrum (within nearly 100 nm wide wavelength range) if light is incident f...

For the first time it is experimentally shown the possibility of planar defect induction in chiral liquid crystalline plane structure by means of hydrodynamic flow. The behavior of unpolarized light reflection spectrum from chiral liquid crystalline plane structure with planar defect induced by hydrodynamic flow is studied. The possible application...

We investigate spectral peculiarities of multilayer system, consisting of two identical CLC layers and a Rhodamine 6G doped polymethyl metacrylate thin film sandwiched between them. We measure transmission and reflection spectra of the system. A small mismatch between Selective reflection band and corresponding dip in transmission spectrum is obser...

We experimentally investigate fluorescence spectrum properties of multilayer system consisting of Rhodamine 6G doped polymethyl metacrylate thin film sandwiched between two right handed cholesteric liquid crystal layers at various temperatures and pumping powers. We observe fluorescence intensity enhancement while increasing sample temperature from...

In this work we have experimentally investigated optical properties of multilayered structure, consisting of two right handed Cholesteric Liquid Crystal layers with the same pitch and Rhodamine 6G (R6G) doped polymethyl metacrylate (PMMA) thin film sandwiched between them. Particularly transmission spectrum dependence on temperature is studied. The...