Adam Szukalski

Physically transient photonics: random versus distributed feedback lasing based on nanoimprinted DNA.

Room-temperature nanoimprinted, DNA-based distributed feedback (DFB) laser operation at 605 nm is reported. The laser is made of a pure DNA host matrix doped with gain dyes. At high excitation densities, the emission of the untextured dye-doped DNA films is characterized by a broad emission peak with an overall line width of 12 nm and superimposed narrow peaks, characteristic of random lasing. Moreover, direct patterning of the DNA films is demonstrated with a resolution down to 100 nm, enabling the realization of both surface-emitting and edge-emitting DFB lasers with a typical line width of <0.3 nm. The resulting emission is polarized, with a ratio between the TE- and TM-polarized intensities exceeding 30. In addition, the nanopatterned devices dissolve in water within less than 2 min. These results demonstrate the possibility of realizing various physically transient nanophotonics and laser architectures, including random lasing and nanoimprinted devices, based on natural biopolymers.

Coherent–incoherent random lasing based on nano-rubbing induced cavities

In this letter we present the results of studies carried out on poly(n-vinylcarbazole) doped with the well-known DCM laser dye. We show that the simple incorporation of highly luminescent dye into a polymeric matrix can form an efficient solid state laser material. Naturally occurring inhomogeneities of a polymeric layer prepared by a drop casting process can scatter out light emitted in the process of photoluminescence in such a way that feedback is introduced to the system and coherent and incoherent random lasing can be observed. Moreover we show that after a nano-scale rubbing process the random lasing phenomenon occurs for a lower energy density of pumping light as compared to the virgin sample, and changes the light amplification nature from incoherent to coherent.

Pyrazoline derivatives with a tailored third order nonlinear optical response

In the present work the third order nonlinear optical response of a series of pyrazoline derivatives has been experimentally investigated. All of the compounds have been prepared as doped poly(methyl methacrylate) thin polymeric films. For the needs of this study the third harmonic generation Maker fringes technique has been employed by using 30 ps laser pulse duration and 1064 nm excitation wavelength. A variety of push–pull groups of pyrazoline-based derivatives have been studied in order to relate the structural properties with the optical nonlinearity. More specifically, the molecules under investigation have in several cases different electro accepting groups, which are located in various positions of the molecular structure providing two pairs of structural isomers. The experimental results demonstrate a high dependence of the optical nonlinearity due to the functionalization with the different moieties on the pyrazoline derivatives. This fact promotes this class of materials as promising candidates for photonics and optoelectronics applications, where the control of the molecular structure as a means of tailoring the optical nonlinearities is crucial.

Amplified spontaneous emission of Rhodamine 6G embedded in pure deoxyribonucleic acid

Deoxyribonucleic acid (DNA) is commonly viewed as a genetic information carrier. However, now it is recognized as a nanomaterial, rather than as a biological material, in the research field of nanotechnology. Here, we show that using pure DNA, doped with rhodamine 6G, we are able to observe amplified spontaneous emission (ASE) phenomenon. Moderate ASE threshold, photodegradation, and reasonable gain coefficient observed in this natural host gives some perspectives for practical applications of this system in biophotonics. Obtained results open the way and will be leading to construction of truly bio-lasers using nature made luminophores, such as anthocyanins.

Lasing and random lasing based on organic molecules

In this article we present the results of studies carried out on the selected polymeric systems doped with luminescent dyes. Our studies focused on polymers like DNA-CTMA and PVK which were doped with common laser dyes Rh6G and DCM. We show that simple incorporation of highly luminescent dye into polymeric matrix can form ;efficient solid laser materials. Moreover, naturally occurring inhomogeneities of polymeric layers prepared by a drop casting process can scatter out pumping light in such a way that a feedback is introduced to the system and coherent and incoherent random lasing can be observed.

Random lasing in dye doped bio-organic based systems: recent experiments and stochastic approach

We review the results of recent experimental studies on random lasing phenomenon in biopolymeric matrices: DNA-CTMA and starch, loaded with different luminescent dyes (DCNP and Rh6G). New experimental results for DNA-CTMA:DCNP system are presented. The random lasing originates due to the light scattering induced by formation of microcrystals or clusters in the bulk of biosystem. We propose a simple model for light transport in the scattering medium accounting for the inhomogeneities in polymer matrices simulated using Monte Carlo method and present some preliminary results related to ray scattering.

Random lasing in liquid and solid solutions oversaturated with organic laser dye

We present the results of studies carried out for oversaturated solutions with common laser dye 4- (Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) and 3-(1,1-Dicyanoethenyl)-1-phenyl-4,5- dihydro-1H-pyrazole (DCNP) nonlinear chromophore. We show that oversaturating the solution leads to formation of crystals suspension resulting in strong Mie scattering and thus random laser operation can be observed. The formation of aggregates can be induced be oversaturating the solution or by injection of non-solvent to the dye solution, leading to reduction of solubility limit. Similar situation can be obtained for polymeric matrices for which small crystals are precipitated during layer formation (solvent evaporation) when film is casted from the solution.

Second harmonic generation and two-photon excitation fluorescence from individual nanocrystals of pyrazoline derivatives

We measure the quadratic nonlinear optical properties, namely second harmonic generation (SHG) and two-photon excitation fluorescence (TPEF), of nanocrystals of different derivatives of pyrazoline. The derivatives of pirazoline, like for example DCNP are supposed to have high second order nonlinear susceptibility. We use a nonlinear optical microscopy setup, samples were excited with a femtosecond laser operating at 800 nm wavelength, both signals (SHG and TPEF) were measured simultaneously using a dichroic mirror and for SHG a narrow spectral bandwidth filter centered at 400 nm, respectively. The details of the used nonlinear polarimetric microscopy technique can be found in reference. We have produced the nano-size crystals using the precipitation method and estimated the average size of these nanocrystals to be 300 × 600 nm using atomic force microscopy (AFM).

Studies of new organic molecules and hybrid systems for lasing applications

We present experimental results of studies of new organic compounds and hybrid systems which can be used for amplified spontaneous emission (ASE) and lasing applications. As dye molecules we have choose group of pyrazoline derivatives (PRD). Luminescence has been studied for solution of PRD in tetrahydrofuran. ASE has been studied for thin films of PRD in polymethyl methacryalte matrix. For the samples excitation we have used Nd:YAG nanosecond pulsed laser doubled in frequency (λ= 532 nm). We report on light amplification and spectral dye luminescence narrowing in function of different excitation pulse energy densities.

Random lasing in bio-polymeric dye-doped systems

The potential for photonic application of modified deoxyribonucleic acid with cationic surfactant cetyltrimethylammonium chloride, has been shown in many fields. Here we present results of detailed studies on random lasing achieved in a biopolymer based matrix loaded with luminescent dye. The random lasing originates due to the light scattering induced by formation of nanocrystals in the bulk biosystem. We show that lasing parameters for bio-polymeric system can be comparable with similar systems based on standard or π-conjugated polymers and may contribute to commercialization of polymeric lasers.