Flexible fully organic indirect detector for megaelectronvolts proton beams

A flexible,fully organic detector for proton beams is presented here.The detector operates in the indirect mode and is composed of a polysiloxane-based scintillating layer coupled to an organic phototransistor,that is assessed for flexibility and low-voltage operation(V=−1 V),with a limit of detection of 0.026 Gy min^(−1).We present a kinetic model able to precisely reproduce the dynamic response of the device under irradiation and to provide further insight into the physical processes controlling it.This detector is designed to target real-time and in-situ dose monitoring during proton therapy and demonstrates mechanical flexibility and low power operation,assessing its potential employment as a personal dosimeter with high comfort and low risk for the patient.The results show how such a proton detector represents a promising tool for real-time particle detection over a large area and irregular surfaces,suitable for many applications,from experimental scientific research to innovative theranostics.

Highly efficient surface-emitting semiconductor lasers exploiting quasi-crystalline distributed feedback photonic patterns

Quasi-crystal distributed feedback lasers do not require any form of mirror cavity to amplify and extract radiation.Once implemented on the top surface of a semiconductor laser,a quasi-crystal pattern can be used to tune both the radiation feedback and the extraction of highly radiative and high-quality-factor optical modes that do not have a defined symmetric or anti-symmetric nature.Therefore,this methodology offers the possibility to achieve efficient emission,combined with tailored spectra and controlled beam divergence.Here,we apply this concept to a onedimensional quantum cascade wire laser.By lithographically patterning a series of air slits with different widths,following the Octonacci sequence,on the top metal layer of a double-metal quantum cascade laser operating at THz frequencies,we can vary the emission from single-frequency-mode to multimode over a 530-GHz bandwidth,achieving a maximum peak optical power of 240mW(190 mW)in multimode(single-frequency-mode)lasers,with record slope efficiencies for multimode surface-emitting disordered THz lasers up to ≈570 mW/A at 78 K and ≈720 mW/A at 20 K and wall-plug efficiencies of η≈1%.