We report on two-photon absorption ~TPA! photocurrent in semiconductor microcavities. We experimentally show a substantial increase in the TPA photocurrent generated, at resonance, in a GaAlAs/GaAs microcavity designed for TPA operation at ;890 nm. An enhancement factor of ;12 000 of the photocurrent is obtained via the microcavity effect, which could have an important impact on the use of TPA ...

The transient current technique (TCT) is widely used in the field of silicon particle detector development. So far, only laser wavelengths with a photon energy larger than or similar to bandgap (single absorption) were used. Recently, measurements using two-photon absorption (TPA) for testing have been carried out first time. Excess carriers are created at focal point beam and thus resolution a...

Previously, we have described a low temperature grown GaAs device that uses single-photon absorption to perform a carrier lifetime limited optical autocorrelation of picosecond optical pulses. In this article, we describe how this same device could be used to perform an autocorrelation of femtosecond optical pulses by utilizing two-photon absorption ~TPA!. Furthermore, we propose how to model a...

Metal halide perovskites have emerged as versatile photonic device materials because of their outstanding optical properties. Here, we report the two-photon absorption (TPA) spectra for $\mathrm{C}{\mathrm{H}}_{3}\mathrm{N}{\mathrm{H}}_{3}\mathrm{Pb}{\mathrm{Br}}_{3}$ perovskite single crystals under linearly and circularly polarized laser pulses. We experimentally determined spin-orbit splitti...

BACKGROUND Skeletal muscle mass (SMM) can be extracted from whole-body scans obtained by X-ray-based dual-photon absorptiometry (DXA). There is a need to establish expected age-dependent values for children and adolescents. METHODS Appendicular lean tissue mass (ALM) was extracted from whole-body DXA scans in 140 healthy children and adolescents (68 females and 72 males). Whole-body SMM was c...

Some 30 years ago, we applied the newly described method of dual photon absorptiometry (DPA) to demonstrate that osteoporotic women with vertebral fractures had lost substantially more bone from the vertebrae than controls. This opened a whole new field of research into the determinants of bone loss and fractures in the axial skeleton and set the stage for subsequent development of dual-energy ...

The objective of this study was to validate the use of bone mineral measurements of the calcaneus bone by dual X-ray and laser (DXL) in a cross-sectional study carried out in an osteoporosis clinic. Measurements of bone mineral density (BMD) at proximal femur and spine were obtained by dual-energy photon X-ray absorptiometry (DEXA). Osteoporosis was defined by a DEXA T-score <-2.5 at the femora...

Promising applications of two-photon absorption (TPA) in high-density optical data storage, two-photon fluorescence microscopy, microfabrication, photodynamic therapy, and other areas of photonics have recently stimulated the search for novel materials with high efficiency of simultaneous (intrinsic) two-photon absorption (TPA). Porphyrins, notably porphyrin oligomers and polymers, deserve a pa...

The two-photon-induced singlet fission was observed in rubrene single crystal and studied by use of femtosecond pump-probe spectroscopy. The location of two-photon excited states was obtained from the nondegenerate two-photon absorption (TPA) spectrum. Time evolution of the two-photon-induced transient absorption spectra reveals the direct singlet fission from the two-photon excited states. The...

In the present work, we have theoretically studied the one and two-photon absorption (OPA and TPA) probabilities of the native D-luciferin molecule and attempted to find the origin of its larger TPA cross-sections in polar solvents than in non-polar ones. The calculations using state-of-the-art linear and quadratic response theory in the framework of time-dependent density functional theory usi...