Laboratory for Functional Nano-materials Photonics

Scientific results:

• Our researchers have developed new synthetic approaches to the production of  colloid perovskite nanocrystals with core-shell structure of the types CsPbBr₃-CdS and CsPbBr₃-SiO₂. The nanocrystals demonstrated a high stability of structural and optical properties in water solutions and the effect of suppression of Auger recombination of photo-excited charge carriers due to the presence of a shell. Later CsPbBr₃-SiO₂ nanocrystals were used for the two-photon imaging of biological objects, while CsPbBr₃-CdS was used for the self-assembly of micron-size superlattices demonstrating photoluminescence that is stable over time when excited by UV radiation.
• A method has been developed for the synthesis of CsPbBr₃ perovskite nanocuboids supporting Mie optical resonances. The produced nanocuboids were applied to metal-dielectric substrates, which allowed to observe low-threshold laser generation in perovskite resonators. We confirmed the polaritonic nature of laser generation. It was found that single-mode polariton laser generation occurs in a nanocuboid with a size of an edge amounting to 190 nm.
• Using the method of recrystallizing thin CsPbBr₃ polycrystalline films under pressure with sizes of perovskite grains ranging from 0.1 to 0.2 μm, we produced films with enhanced  crystallinity of grains of larger dimensions (up to 17 μm). Films with a width of 100 nm demonstrated a record-high optical amplification coefficient for this type of perovskite, 12900 cm^-1. From this film we produced an array of microdisks that manifested low-threshold (14 µJ cm^-2) and high-Q (Q = 1800) laser generation.
• We have produced flexible visualizers of infrared laser radiation based on silicon thread-like microcrystals planted into a polymer membrane. A new platform has been developed on the basis of perovskite nano- and micro-lasers integrated with a one-dimensional photonic crystal to control the orientation of laser radiation and its propagation at the microscale. We developed prototypes of perovskite-based detector of terahertz laser radiation. We developed and tested a model of nonlinear optical heating of a carbon particle during its interaction with laser radiation at a frequency close to the resonance frequency of the particle.   
• Our researchers have demonstrated the efficiency third harmonic generation in arrays of silicon thread-like micro-crystals encapsulated in a polymer membrane. The arrays were produced using lithography (with the use of polystyrene microspheres) and dry etching of the silicon substrate. It has been theoretically and experimentally determined that optical resonances supported by thread-like crystals determine the spectral characteristics of third harmonic generation. At the same time, the intensity of generation signal at the resonance wavelength is several times higher in comparison with the corresponding  value at wavelengths closer to the resonance wavelength. We determined the correlation between the intensity of generation and the length of pumping wave for arrays of thread-like crystals. It has been shown that the produced composite membranes  efficiently transform infrared radiation in a wide spectral range (λ = 1200-1900 nm) to visible light. At the same time, the membranes are flexible and semi-transparent for infrared radiation passing through them.
• We have integrated perovskite nano- and microlasers with a one-dimensional photonic crystal that supports the efficient excitation and long-distance propagation of Bloch surface waves (BSW). The photonic crystal ensures the propagation of coherent radiation of a perovskite laser across distances of up to 50 μm. The observed experimental results are in agreement with numerical computations that confirm that the efficiency of pumping laser radiation into BSWs is over 16%. It has been found that the orientation of BSWs depends on the length of the perovskite resonator and on the efficient refractive index of  BSWs. Unlike perovskite nanolasers with subwave dimensions, microlasers with dimensions of the edge exceeding the length of the radiated wave support narrowly-focused BSWs with an angle of divergence of 9±2°. Moreover, the  planar isotropic of  BSW dispersion allows to shift and direct the beam of laser generation depending on the orientation of the beam of exciting radiation. .
• For the organo-inorganic halide perovskites MAPbI3 and MAPbBr3 we have demonstrated the detection of terahertz pulses propagating in free space. The ultra-fast tuning of conductivity that occurs in perovskite microcrystals and polycrystalline films when they are excited by a femtosecond laser allows to efficiently register terahertz radiation. The results demonstrate the suitability of halide perovskites for producing photoconducting detectors of terahertz radiation and the possibility of their scaling.
• We have developed a new theoretical approach to optimizing the process of nonlinear optical heating of a silicon resonator. The proposed system based on the mode of a ultraresonator in cylindrical silicon particles allows to efficiently transform light falling on a particle into heat given that the frequency of the falling radiation is tuned to suit the frequency of the mode. We determined a bistability mode under conditions of optical heating at an intensity of incident radiation of about  1 mW/μm².

Education and retraining of personnel:

• Employees of the Laboratory made presentations at the «SLALOM» scientific school (28-30 June 2021, Vladivostok, Russia).
• In 2021-2022 we conducted six internships of the Laboratory’s postgraduate students at Bilkent University (Turkey).   

Organizational and infrastructural transformations:

On the grounds of the Laboratory infrastructure has been created for the synthesis of  nanomaterials and for the measurement of their properties for problems of laser generation. On the basis of the assembled facilities we are also conducting laboratory case studies for students of ITMO University.

Collaboration:

• Russian Center of Flexible Electronics (Russia): collaboration in the field of new materials and nanomaterials for photodetection and display matrices.
• JSC «Specialized Design and Technology Bureau «Koltsova»: searching for new approaches to the creation of segment light-emitting diodes and light-emitting matrices based on new nanomaterials.
• PJSC «Gazprom neft»: we have conducted the project «A study of technologies and methods of the use of flexible electronics» devoted to the search for existing solutions and technologies (including additive) for flexible electronics in application to IoT/IIoT, wearable devices.