arXiv subjects

Ankur Khapre

Publications and source records attributed to Ankur Khapre.

4 recordsLinked to original sources

arXiv2026

Large-Area Patternable Solar-Powered Bistable Organic Crystalline Film for Nonlinear Optical Communication

Reversible control of crystal symmetry offers a powerful route to programmable optical functionality. However, achieving solid-state bistability between centrosymmetric and non-centrosymmetric crystalline phases remains a formidable challenge; examples of materials that enable stable switching of second-order nonlinear optical (NLO) responses are exceptionally rare. Here we report a solar-powered, symmetry-bistable organic material based on the photoisomerizable molecule (E/Z)-2-(4-(4-bromophenyl)thiazol-2-yl)-3-(4- (dimethylamino)phenyl)acrylonitrile (E/Z-BTDPA). The crystallizable E- and Z-isomers adopt distinct molecular packing arrangements that reversibly toggle between these states, controlling second-order NLO activity. The E-form exhibits strong second-harmonic generation (SHG), whereas the Z-form is SHG-inactive and displays twophoton luminescence. This bistable behavior is retained in flexible thin films, where sunlight-driven photoisomerization enables reversible photoswitching of the second-order electric susceptibility (\c{hi} 2), large-area optical patterning, and real-time NLO communication via waveform generation and text-string transcription at telecommunication wavelengths. This sustainable strategy bypasses rigid inorganic architectures, establishing photoinduced symmetry bistability as a scalable paradigm for all-optical computing and advanced communication networks.

physics.optics↗

arXiv2025

Unveiling Mechanical Motions in Non-linear Optical Organic Micro Ring Resonators

This work demonstrates the multifaceted dynamic motion and three-dimensional (3D) spatial manipulation of organic micro ring resonators (MRRs). The MRRs are fabricated via surface-tension-assisted self-assembly of 2,2'-((1E,1'E)-hydrazine-1,2-diylidenebis(methaneylylidene))bis(3,5-dibromophenol) (HDBP), exhibiting nonlinear optical (NLO) emission and frequency comb-type whispering gallery modes. Interestingly, the MRRs are micromechanically reconfigurable into various strained architectures, including lifting, transferring, vertical standing, axial spinning, and wheel-like rolling, using an atomic force microscopy cantilever tip. The MRRs retained their photonic traits throughout these dynamic motions, underscoring their mechanical robustness. Notably, the demonstration of axial spinning and rolling locomotion extends the manipulation capabilities beyond two-dimensional control, enabling complete 3D spatial control. These results establish a foundational platform for next-generation NLO mechanophotonic systems, where reconfigurable smart and soft photonic elements can be dynamically controlled with high spatial precision.

physics.optics↗

arXiv2025

Organic Crystal Active Waveguide as an All-Angle Signal Receiver and Transmission Platform for Visible Light Communication

Organic crystal waveguides, known for excellent light-guiding and photonic versatility, present a promising alternative to conventional optical media in visible light communication (VLC) systems. In a novel approach, the high photoluminescence quantum yield organic crystal 2,2dash-((1E,1Edash)-hydrazine-1,2-diylidenebis(methaneylylidene))diphenol (SAA) is used as an optical waveguide medium for real-time data communication in the visible range, employing a microcontroller unit with on off keying modulation. Leveraging its spectral properties, the SAA crystal demonstrates dual active and passive waveguiding capabilities for signal modulation. Error-free signal detection is achieved thanks to the smooth, defect-free surface morphology of the crystal. The relationship between incident angle and light intensity reveals stable fluorescence under narrow angle excitation, positioning the crystal as an all-angle signal receiver that surpasses conventional optical fibers. A real time data transfer setup is demonstrated, enabling direct transmission from a serial interface and accurate reconstruction of grayscale images. This represents the first implementation of a fully organic crystal-based VLC platform, integrating wavelength conversion, omnidirectional waveguiding, and real time signal processing. The results establish a foundation for compact, efficient, and integrable photonic communication technologies.

physics.optics↗

arXiv2024

Powering Monolithic and Hybrid Organic Optical Waveguides via Integrated Focused Micro-LEDs for Sustainable Photonic Circuits

In the domain of mechanophotonics, achieving real-time applicability of organic crystals in visible light communication (VLC) technologies necessitates affordable light-emitting diodes (LEDs) as sources of light to run photonic devices through sustainable methods. Here in, we demonstrate an efficient strategy to excite (Z)-3-(3',5'-bis(trifluoromethyl)-[1,1'-biphenyl]-4-yl)-2-(4-methoxyphenyl) acrylonitrile (CF3OMe), 9,10-bis(phenylethynyl)anthracene (BPEA) and 2,2'-((1E,1'E)-hydrazine-1,2-diylidenebis(methaneylylidene))diphenol (SAA) flexible crystal waveguides utilizing UV LED source and transduce respective blue, orange and yellow fluorescence signals. The capability of the focused LED lies in its ability to (i) energize mechanically bent crystals at an angle of 180°, (ii) evanescently excite the FL of a SAA waveguide using the FL of CF3OMe waveguide through energy transfer, and (iii) excite and split different signals in a 2X2 hybrid directional coupler based on SSA-BPEA crystals. These demonstrations underscore the practicality of the proposed technique for sustainable applications in photonic systems related to VLC.

physics.optics↗