Incidence of different types of cancer in the follow-up period after primary diagnosis and treatment of melanoma. Single-centre 4-year follow-up on a population of 709 patients.

Introduction: Follow-up plays a key role in melanoma management, especially in the first years after diagnosis. During this period it is crucial to assess possible recurrence, progression of the disease or treatment complications. An important aspect is also the possibility of formation of new primary foci or other skin cancers. Aim: To assess the coincidence of skin lesions and cancers among the melanoma patients. Material and methods: Patients treated in the Comprehensive Cancer Centre between 2019 and 2022 were retrospectively analysed for occurrence of skin lesions diagnosed during the follow-up, and confirmed by biopsy. The lesions considered included skin cancers, dysplastic nevus and actinic keratosis. Results: In 100 (14%) out of 709 enrolled patients, 184 lesions were diagnosed. In 7 patients it was melanoma, in 49 BCC, and in 16 SCC. Dysplastic nevus and actinic keratosis were excised in 28 and 14 patients, respectively. More than one site of the skin lesion was observed in 39 patients, and more than one type of the lesion in 13 patients. Patients with lesions were on average 8.6 years older (p < 0.001), had less advanced tumours (p = 0.010), and primary melanoma was more often located on the head and neck (p = 0.056). Conclusions: Among melanoma patients, particular attention must be paid to, apart from early detection of melanoma recurrence and progression, the occurrence of new primary foci or independent skin cancers.

Electronic and Optical Properties of InAs QDs Grown by MBE on InGaAs Metamorphic Buffer.

We present the optical characterization of GaAs-based InAs quantum dots (QDs) grown by molecular beam epitaxy on a digitally alloyed InGaAs metamorphic buffer layer (MBL) with gradual composition ensuring a redshift of the QD emission up to the second telecom window. Based on the photoluminescence (PL) measurements and numerical calculations, we analyzed the factors influencing the energies of optical transitions in QDs, among which the QD height seems to be dominating. In addition, polarization anisotropy of the QD emission was observed, which is a fingerprint of significant valence states mixing enhanced by the QD confinement potential asymmetry, driven by the decreased strain with increasing In content in the MBL. The barrier-related transitions were probed by photoreflectance, which combined with photoluminescence data and the PL temperature dependence, allowed for the determination of the carrier activation energies and the main channels of carrier loss, identified as the carrier escape to the MBL barrier. Eventually, the zero-dimensional character of the emission was confirmed by detecting the photoluminescence from single QDs with identified features of the confined neutral exciton and biexciton complexes via the excitation power and polarization dependences.

Metamorphic Buffer Layer Platform for 1550 nm Single-Photon Sources Grown by MBE on (100) GaAs Substrate.

We demonstrate single-photon emission with a low probability of multiphoton events of 5% in the C-band of telecommunication spectral range of standard silica fibers from molecular beam epitaxy grown (100)-GaAs-based structure with InAs quantum dots (QDs) on a metamorphic buffer layer. For this purpose, we propose and implement graded In content digitally alloyed InGaAs metamorphic buffer layer with maximal In content of 42% and GaAs/AlAs distributed Bragg reflector underneath to enhance the extraction efficiency of QD emission. The fundamental limit of the emission rate for the investigated structures is 0.5 GHz based on an emission lifetime of 1.95 ns determined from time-resolved photoluminescence. We prove the relevance of a proposed technology platform for the realization of non-classical light sources in the context of fiber-based quantum communication applications.

InP-Substrate-Based Quantum Dashes on a DBR as Single-Photon Emitters at the Third Telecommunication Window.

We investigated emission properties of photonic structures with InAs/InGaAlAs/InP quantum dashes grown by molecular beam epitaxy on a distributed Bragg reflector. In high-spatial-resolution photoluminescence experiment, well-resolved sharp spectral lines are observed and single-photon emission is detected in the third telecommunication window characterized by very low multiphoton events probabilities. The photoluminescence spectra measured on simple photonic structures in the form of cylindrical mesas reveal significant intensity enhancement by a factor of 4 when compared to a planar sample. These results are supported by simulations of the electromagnetic field distribution, which show emission extraction efficiencies even above 18% for optimized designs. When combined with relatively simple and undemanding fabrication approach, it makes this kind of structures competitive with the existing solutions in that spectral range and prospective in the context of efficient and practical single-photon sources for fiber-based quantum networks applications.