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Precise excitation of cavitation is a promising mechanism for microsurgery procedures and targeted drug delivery enhancement. The underlying phenomenon of interest, jetting behaviour of oscillating cavitation bubbles, occurs due to near-surface interactions between the boundary, liquid, and bubble. Within this study we measured boundary effects on the cavitation bubble dynamics and morphology, with an emphasis on observation and measurement of jetting behaviour near tissue-phantom biointerfaces. An important mechanism of boundary poration has been observed using time-resolved optical microscopy and explained for different tissue-phantom surface densities and Young’s modulus. Below a critical distance to the boundary, around γ = 1.0, the resulting jets penetrated the tissue-phantom, resulting in highly localized few micrometer diameter jets.

In this manuscript we present a true pulse-on-demand laser design concept using two different approaches. First, we present a fiber master oscillator power amplifier (MOPA) based quasi-continuous wave (CW) laser, working at high modulation bandwidths, for generation of nanosecond pulses. Second, we present a hybrid chirped pulse amplification (CPA)-based laser, combining a chirped-pulse fiber amplifier and an additional solid-state amplifier, for generation of femtosecond pulses. The pulse-on-demand operation is achieved without an external optical modulator/shutter at high-average powers and flexible repetition rates up to 40 MHz, using two variants of the approach for near-constant gain in the amplifier chain. The idler and marker seed sources are combined in the amplifier stages and separated at the out using either wavelength-based separation or second harmonic generation (SHG)-generation-based separation. The nanosecond laser source is further applied to high throughput processing of thin film materials. The laser is combined with a resonant scanner, using the intrinsic pulse-on-demand operation to compensate the scanner’s sinusoidal movement. We applied the setup to processing of indium tin oxide (ITO) and metallic films on flexible substrates.

Tissue diseases and related disorders need to be first recognized using diagnostic methods and then later treated by therapeutic methods–a joint procedure called theranostics. One of the main challenges in the field of retinal therapies remains in the success of the treatment, typically improving the local metabolism, by sparing the surrounding tissue and with the immediate information of the laser effect. In our study, we present a concept for real-time controlled tissue theranostics on a proof-of-concept study capable of using a single tunable ps laser source (in terms of irradiance, fluence, and repetition rate), done on ex-vivo human retinal pigment epithelium. We have found autofluorescence intensity and lifetime imaging diagnostics very promising for the recognition and quantification of laser effects ranging from selective non-destructive molecular tissue modification to complete tissue ablation. The main novelty of our work presents the developed algorithm for optimized theranostics based on the model function used to quantify laser-induced tissue changes through the diagnostics descriptors, fluorescence lifetime and fluorescence intensity parameters. This approach, together with the operation of the single adaptable laser source, can serve as a new theranostics method in personalized medicine in the future not only limited to treat retinal diseases.

A low-power source, such as a gain-switched laser diode, usually requires several amplification stages to reach sufficient power levels. When operating in burst mode, a correct input burst shape must be determined in order to compensate for gain saturation of all amplifier stages. In this paper we report on closed-form equations that enable saturation compensation in multiamplifier setups, which eliminates the need for an adaptive feedback loop. The theoretical model is then evaluated in an experimental setup.