Tigran Baghdasaryan

Tigran Baghdasaryan
Vrije Universiteit Brussel | VUB · Applied Physics and Photonics (TONA)

Postdoctoral fellow

About

51
Publications
6,663
Reads
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274
Citations
Additional affiliations
September 2010 - present
Vrije Universiteit Brussel
Position
  • Multi-photon grating inscription in photonic crystal fibers
September 2010 - April 2015
Vrije Universiteit Brussel
Position
  • PhD Student
Education
September 2009 - July 2010
Vrije Universiteit Brussel
Field of study
  • Erasmus Mundus Master in Photonics
September 2008 - July 2009
KTH Royal Institute of Technology
Field of study
  • Photonics
September 2007 - July 2008
Yerevan State University
Field of study
  • Optics

Publications

Publications (51)
Article
Full-text available
During grating inscription in photonic crystal fibers (PCFs) the intensity of the inscribing laser beam is non-uniformly distributed over the core region due to the interaction with the air holes in the fiber’s microstructure. In this paper we model and study the non-uniformity of the index modification and its influence on the grating reflection s...
Article
This paper reviews the state-of-the-art of grating fabrication in silica and polymer microstructured optical fibres. It focuses on the difficulties and challenges encountered during photo-inscription of such gratings and more specifically on the effect of the air hole lattice microstructure in the cladding of the fibre on the transverse coupling of...
Article
Full-text available
We numerically studied the focusing properties of a special type of graded index photonic crystal media, i.e., the so-called photonic crystal Mikaelian lenses (PCMLs). We considered PCMLs with a varying air hole diameter and with a varying air hole pitch in hexagonal and rectangular lattices, and we compared their frequency response and polarizatio...
Article
Full-text available
We studied the influence of the fiber orientation on the growth of fiber Bragg gratings (FBGs) in pure silica microstruc-tured optical fibers (MOFs) during femtosecond UV laser inscrip-tion. To do so we simulated the transverse coupling efficiency as a function of the relative angle between the inscribing laser beam and the internal microstructure...
Article
Full-text available
We have studied transverse propagation of femtosecond pulse duration laser light through the microstructure of hexagonal lattice photonic crystal fibers. Our results provide insight in the role of the microstructure on the amount of optical power that reaches the core of the PCF, which is of particular importance for grating inscription application...
Article
This paper reports the characterization of two scintillating materials in powder form, Gadox and YVO embedded in a light-activated resin, used in a probe developed for oncological brachytherapy in-vivo dosimetry. The materials were characterized in terms of internal absorption, scintillation decay time, and light yield. The measurement of the optic...
Article
Full-text available
Optical fibers provide a favorable medium for nonlinear optical processes owing to the small mode field size and concurrently high optical intensity combined with the extended interaction lengths. Second harmonic generation (SHG) is one of those processes that has been demonstrated in silica glass optical fibers. Since silica is centrosymmetric, ge...
Article
Full-text available
We report on an extrinsic surface plasmon-enhanced refractometer based on cladding mode resonance excitation in a photonic crystal fiber (PCF) equipped with a straight fiber Bragg grating (FBG). First, we show that the lattice pitch and the air hole diameter of the PCF microstructure define the spectral location of the excited cladding mode resonan...
Article
Full-text available
Applications associated with complex, structured optical fibers having no circular symmetry often require information about their specific angular orientation. Such cases include, for example, splicing, sophisticated mode coupling, selective fiber Bragg gratings inscription, or direction-sensitive sensing. Besides the external angular orientation o...
Conference Paper
We present our latest results on the design and fabrication of mode-field conversion tapers for low-loss optical interconnects. These structures are fabricated by means of two-photon polymerization-based 3D nanoprinting. We experimentally demonstrate that our 3D nanoprinted downtapers outperform conventional lensed fibers for low-loss edge coupling...
Article
We present a design and fabrication approach for 3D printed polymer microstructured optical fiber tapers on standard single-mode glass fibers for efficient and compact mode-field conversion. This paves the way towards complex functionalized fiber tips for various applications, like sensors and beam shaping components, currently limited by the mode-...
Article
Full-text available
jats:p>Emerging applications requiring light beam manipulation, such as high-efficiency sunlight concentrators for solar cells, switchable micro-lens arrays for autostereoscopic displays, tunable lenses for augmented reality goggles, auto-focusing spectacles, and smart contact lenses, mostly depend on one or more active optical components with the...
Article
Full-text available
Mathematical description of the wave phenomena in nano-optics and quantum mechanics is similar and requires wavelength-scale analysis of wave interaction with nano-layers in optics and micro-particle interaction with potential barriers or wells in quantum mechanics. Traditionally, when dealing with boundary problems in nano-optics and quantum mecha...
Article
Full-text available
An alternative expression for the Poynting vector for monitoring electromagnetic energy flow in confined regions of evanescent waves is presented. This expression is an intrinsic integrable function of the boundary problem solution in the method of single expression (MSE). The peculiarity of the MSE is the fact that it does not exploit the superpos...
Article
The Fiber Bragg Gratings (FBGs) inside Photonic Crystal Fibers having high fiber birefringence, such as in PCF with butterfly shape microstructure, are characterized by two Bragg peaks. The spectral distance between these two peaks is not affected by a change of temperature or by a longitudinally applied strain, but this spectral separation evolves...
Article
Fiber Bragg grating inscription with infrared femtosecond pulsed lasers in photonic crystal fiber is far from being trivial due to the presence of air holes in the cladding region and the non-linear nature of the absorption process inducing the required refractive index changes. We have studied this problem numerically and experimentally for a phas...
Article
Full-text available
It is common belief that photonic crystals behave similarly to isotropic and transparent media only when their feature sizes are much smaller than the wavelength of light. Here, we counter that belief and we report on photonic crystals that are transparent for anomalously high normalized frequencies up to 0.9, where the crystal's feature sizes are...
Conference Paper
We first numerically studied the alignment peculiarities and then successfully inscribed a 4 dB strong fiber Bragg grating in a hexagonal lattice photonic crystal fiber in less than 4 seconds using a femtosecond pulse laser at 1030 nm.
Article
We report on efficient optical beam-steering using a hot-embossed reflective blazed grating in combination with liquid crystal. A numerical simulation of the electrical switching characteristics of the liquid crystal is performed and the results are used in an FDTD optical simulator to analyze the beam deflection. The corresponding experiment on th...
Conference Paper
Fiber Bragg gratings have been essential elements in fiber optical communication for more than two decades. Although writing gratings using different inscription methods in step-index fibers has become a standard procedure, femtosecond laser based fabrication of such gratings in specialty fibers such as photonic crystal fibers (PCFs) has proven not...
Article
In this work, we report two types of electrically tunable photonic devices with circularly symmetric polarization independent beam steering performance (beam condensing resp. beam broadening). The devices consist of circular micro grating structures combined with nematic liquid crystal (LC) layers with anti-parallel alignment. A single beam deflect...
Conference Paper
Fiber Bragg grating (FBG) inscription methods based on femtosecond laser sources are becoming increasingly popular owing to the (usually) non-linear nature of the index modification mechanism and to the resulting advantages. They allow, for example, fabricating fiber gratings that can survive temperatures exceeding 700°C, which can be an asset in t...
Conference Paper
We have numerically identified hexagonal lattice parameters for PCF cladding that allow point-by-point grating writing. We designed and fabricated a PCF with suitable parameters and successfully inscribed a femtosecond point-by-point Bragg grating.
Conference Paper
Full-text available
In this article, we describe an electrically switchable light beam steering component, based on the combination of microprism structures and nematic liquid crystals, which effectively deflects both a laser beam and a collimated white light beam with a controllable steering range of 38.
Conference Paper
Full-text available
In this work, the reverse replication of circular micro grating structures on glass substrates is implemented using an ultra-violet curable resin and a polydimethylsiloxane (PDMS) mold which has the same structure as the original circular grating master. Two different techniques (“double PDMS replication” and “polymer- PDMS replication”) are employ...
Article
Microstructured optical fibers (MOFs) are a major achievement in the field of optical fiber technology. Owing to their unprecedented design flexibility, MOFs have found numerous applications in various fields of photonics. By adapting the parameters of the holey cladding, MOFs with tailored dispersion properties, large mode area, endlessly single m...
Article
New methods for fiber Bragg grating inscription in optical fibers use femtosecond laser sources, which can induce refractive index changes even in non-photosensitive fibers and which allow achieving gratings that remain stable at high temperatures. The index change takes place as a result of a highly non-linear multi-photon absorption process. Alth...
Conference Paper
Transverse light propagation through the air holed cladding of microstructured optical fibers (MOFs) has recently attracted interest owing to its importance for several applications such as fiber grating writing, particle trapping in hollow core fibers, all optical switch devices, etc. The air holes in the MOF cladding region impede efficient deliv...
Conference Paper
Photonic Crystal Fibres (PCFs) are well known for allowing the implementation of specific waveguiding features that cannot be achieved with conventional optical fibres. This results from the design flexibility of the holey structure in the PCF cladding and/or core regions. Today PCFs have found applications for example in supercontinuum generation,...
Article
Full-text available
We studied the influence of the angular orientation of a photonic crystal fiber (PCF) on the optical power that reaches the fiber core during femtosecond grating inscription at 267 nm and 800 nm. In our numerical study we considered two types of PCFs: three PCF designs with a standard hexagonal lattice and one highly birefringent PCF with three row...
Conference Paper
We review the state-of-the-art in photonic crystal fiber (PCF) based mechanical sensing. We then introduce our recently developed highly birefringent PCF that allows pressure and force sensing when combined with a fiber Bragg grating sensor. We clarify the measurement principle and explain how the optimized microstructure of the PCF yields its reco...
Article
Photonic crystal fibers (PCFs) offer great design flexibility as their internal microstructure can be tailored to achieve a wide range of optical guiding properties adapted to many different applications. Fiber Bragg grating fabrication in such fibers is now extensively investigated to enable new fiber sensor and all-fiber laser applications. Grati...
Article
One of the recent methods of grating inscription is based on inducing an array of highly localized index changes in the silica core of a fiber by tightly focused high intensity laser pulses. There were already several reports of such point-by-point gratings in conventional step index fibers. Applying this technique to photonic crystal fibers (PCFs)...
Conference Paper
Fiber Bragg grating (FBG) inscription in microstructured optical fibers (MOF) is accompanied (by) low intensity and contrast ratio of the interference. Nanosecond and femtosecond ultraviolet exposure reveal the feasibility of gratings pure silica MOFs.
Article
Full-text available
Electrodynamical model of a classical distributed Bragg reflector (DBR) consisting of alternating quarter-wave layers of high and low permittivity is considered at the plane wave normal incidence. Reflective characteristics of DBR possessing absorption loss in constituting layers are analysed via correct wavelength-scale boundary problem solution b...
Conference Paper
Worldwide, higher-order modulation formats are intensively investigated to further increase spectral efficiency for building next generation optical transport networks. Coherent receivers and digital electronic equalizers are hereby discussed as the key enablers for applying very high spectral efficient wavelength division multiplexed (WDM) signals...
Conference Paper
Full-text available
An extension of the method of single expression (MSE) for analysis of plane electromagnetic wave oblique incidence on a wavelength-scale multilayer structure consisting of dielectric and magnetic layers is performed. Corresponding Helmholtzpsilas equations, boundary conditions and the expression for power flow density in complex media are derived i...
Conference Paper
Full-text available
An extension of the method of single expression (MSE) for the analysis of plane electromagnetic wave oblique incidence on a dielectric slab is performed. Corresponding Helmholtz's equation, boundary conditions and the expression for power flow density are derived in the terms of MSE for TE and TM electromagnetic waves. TE wave oblique incidence on...
Conference Paper
The focusing property of thick chirped hologram PDLC gratings is investigated theoretically. Focal length's formula for linearly chirped gratings is obtained by using Bragg condition. Diffraction efficiency dependence on incident angle in focus point is calculated numerically and enhanced bandwidth is observed.

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