A heterogeneously integrated lithium niobate-on-silicon nitride photonic platform.

The availability of thin-film lithium niobate on insulator (LNOI) and advances in processing have led to the emergence of fully integrated LiNbO electro-optic devices. Yet to date, LiNbO photonic integrated circuits have mostly been fabricated using non-standard etching techniques and partially etched waveguides, that lack the reproducibility achieved in silicon photonics. Widespread application of thin-film LiNbO requires a reliable solution with precise lithographic control.

Ultrafast tunable lasers using lithium niobate integrated photonics.

Early works and recent advances in thin-film lithium niobate (LiNbO) on insulator have enabled low-loss photonic integrated circuits, modulators with improved half-wave voltage, electro-optic frequency combs and on-chip electro-optic devices, with applications ranging from microwave photonics to microwave-to-optical quantum interfaces. Although recent advances have demonstrated tunable integrated lasers based on LiNbO (refs. ), the full potential of this platform to demonstrate frequency-agile, narrow-linewidth integrated lasers has not been achieved.

Low-noise frequency-agile photonic integrated lasers for coherent ranging.

Frequency modulated continuous wave laser ranging (FMCW LiDAR) enables distance mapping with simultaneous position and velocity information, is immune to stray light, can achieve long range, operate in the eye-safe region of 1550 nm and achieve high sensitivity. Despite its advantages, it is compounded by the simultaneous requirement of both narrow linewidth low noise lasers that can be precisely chirped. While integrated silicon-based lasers, compatible with wafer scale manufacturing in large volumes at low cost, have experienced major advances and are now employed on a commercial scale in data centers, and impressive progress has led to integrated lasers with (ultra) narrow sub-100 Hz-level intrinsic linewidth based on optical feedback from photonic circuits, these lasers presently lack fast nonthermal tuning, i.

[The x-ray radiological semeiotics of the pain syndrome in a traumatic lesion of the brachial plexus].

X-ray radionuclide studies revealed a variety of morphological changes at the cervicothoracic levels of the spinal cord and its meninges. Despite a preganglionary injury to the brachial plexus, there was a clear-cut correlation between the level and nature of an injury on the one hand, and the severity of the pain syndrome, on the other. A more significant progression was observed in abruption of the inferior roots than in that of superior ones.

[A trial of the clinical use of the Testascan computerized gamma tomograph in neurosurgical pathology].

The paper outlines the diagnostic potentialities of the first Russian multidetector Testascan gamma-tomograph. With this, three different radio pharmaceuticals (RP) were used; 99mTC-GM PAO for examining cerebral circulatory disorders, 99mTC pertechnetate for visualizing tumor foci, and 99mTC-DTPK for studying impaired cerebral liquor pathway. Regional cerebral blood supply was studied in 78 patients with arterial aneurysms and arteriovenous malformations, with stenoses and thromboses of the great arterial trunks, as well in patients with brain injury sequelae and hypophyseal, craniofascial, and cavernous sinus tumors, VIII-neurinomas, meningiomas of the pyramid of the temporal bone.