41 research outputs found
Pure-quartic solitons
Temporal optical solitons have been the subject of intense research due to their intriguing physics and applications in ultrafast optics and supercontinuum generation. Conventional bright optical solitons result from the interaction of anomalous group-velocity dispersion and self-phase modulation. Here we experimentally demonstrate a class of bright soliton arising purely from the interaction of negative fourth-order dispersion and self-phase modulation, which can occur even for normal group-velocity dispersion. We provide experimental and numerical evidence of shape-preserving propagation and flat temporal phase for the fundamental pure-quartic soliton and periodically modulated propagation for the higher-order pure-quartic solitons. We derive the approximate shape of the fundamental pure-quartic soliton and discover that is surprisingly Gaussian, exhibiting excellent agreement with our experimental observations. Our discovery, enabled by precise dispersion engineering, could find applications in communications, frequency combs and ultrafast lasers
Fully Phase Stabilized Quantum Cascade Laser Frequency Comb
The road towards the realization of quantum cascade laser (QCL) frequency combs [1,2] has undoubtedly attracted ubiquitous attention from the scientific community. These devices promise to deliver an all-in-one (i.e. a single, miniature, active device) frequency comb synthesizer in a range as wide as the QCL spectral coverage itself (from about 4 microns to the THz range), with the unique possibility to tailor their spectral emission by band structure engineering. For these reasons, vigorous efforts have been spent to characterize the emission of four-wave-mixing (FWM) multi-frequency QCLs, aiming to seize their comb-like mode-locked operation [3â6]
Photonic molecules and spectral engineering
This chapter reviews the fundamental optical properties and applications of
pho-tonic molecules (PMs) - photonic structures formed by electromagnetic
coupling of two or more optical microcavities (photonic atoms). Controllable
interaction between light and matter in photonic atoms can be further modified
and en-hanced by the manipulation of their mutual coupling. Mechanical and
optical tunability of PMs not only adds new functionalities to
microcavity-based optical components but also paves the way for their use as
testbeds for the exploration of novel physical regimes in atomic physics and
quantum optics. Theoretical studies carried on for over a decade yielded novel
PM designs that make possible lowering thresholds of semiconductor microlasers,
producing directional light emission, achieving optically-induced transparency,
and enhancing sensitivity of microcavity-based bio-, stress- and
rotation-sensors. Recent advances in material science and nano-fabrication
techniques make possible the realization of optimally-tuned PMs for cavity
quantum electrodynamic experiments, classical and quantum information
processing, and sensing.Comment: A review book chapter: 29 pages, 19 figure
Endoscopic Detection of Gastric Metastases in Skin Melanoma
Aim. A clinical description of disseminated skin melanoma with endoscopic observation of its pathognomonic pigmented metastases into the stomach.Key points. A 66-yo patient was hospitalised with dyspnoea, general weakness, cough and suspected community-acquired pneumonia. The patient had a complex examination, including computed tomography, which revealed a presumed malignancy of the right lung with secondary changes in the chest and abdominal organs. Esophagogastroduodenoscopy (EGDS) visualised multiple pigmented spots and raised black plaques in cardia and the gastric body diagnosed as a metastasising melanoma in stomach. Endoscopic veriïŹcation of the metastases conïŹrmed the correct diagnosis of primary skin melanoma.Conclusion. Metastatic melanoma of the gastrointestinal tract has non-speciïŹc symptoms and most often occurs during the dissemination process. Endoscopy should be used to correctly verify pigmented mucosal lesions, necessarily allowing for non-pigmented gastric neoplasms in patients with skin melanoma in history