Dynamic Photoelastic Analysis of Stress Distribution in Simulated Canals Using Rotary Instruments with Varied Tip and Taper Sizes: A Quasi-3D Approach.

Introduction: To compare the stress produced on the walls of simulated canals by rotary instruments with varied tip and taper sizes.

Methods: Ninety isotropic transparent blocks, each containing a 60-degree curved canal, were distributed into 18 groups (n = 5) based on the instrument tip (sizes 10, 15, 20, 25, 30, and 35) and taper (sizes 0.02, 0.

Single-frequency optical parametric oscillator intracavity-pumped by a visible VECSEL for low-noise down-conversion to 1.55 µm.

We report, to the best of our knowledge, the first optical parametric oscillator (OPO) pumped by a visible AlGaInP-based vertical-external-cavity surface-emitting laser (VECSEL). Tunable emission over 1155-1300 nm in the signal and 1474-1718 nm in the idler are observed by temperature adjustment of a 40 mm-long 5%-MgO:PPLN crystal intracavity-pumped at 690 nm. When optimized for low oscillation threshold, and by implementing resonant idler output-coupling (T = 1.

Monolithic VECSEL for stable kHz linewidth.

Vertical-external-cavity surface-emitting semiconductor lasers (VECSELs) are of increasing interest for applications requiring ultra-coherence and/or low noise at novel wavelengths; performance that is currently achieved via high-Q, air-spaced resonators to achieve long intra-cavity photon lifetimes (for the so-called class-A low noise regime), power scaling and high beam quality. Here, we report on the development of a compact, electronically tunable, monolithic-cavity, class-A VECSEL (monolithic VECSEL) for ultra-narrow free-running linewidths. A multi-quantum-well, resonant periodic gain structure with integrated distributed Bragg reflector (DBR) was optically-bonded to an air-gap-free laser resonator created inside a right-angle fused-silica prism to suppress the influence of environmental noise on the external laser oscillation, thus achieving high stability.

Low phase noise operation of a cavity-stabilized 698 nm AlGaInP-based VECSEL.

We report for the first time a high performance, single frequency AlGaInP-based VECSEL (vertical-external-cavity surface-emitting-laser) with emission at 698 nm, targeting the clock transition of neutral strontium atoms. Furthermore, we present comprehensive noise characterization of this class-A semiconductor laser, including the residual fast phase noise in addition to the frequency and relative intensity noise. The low noise VECSEL has output power at around 135 mW with an estimated linewidth of 115 Hz when frequency stabilized via the Pound-Drever-Hall (PDH) technique to a high finesse reference cavity, without intermediate stabilization.

Quasi-3D dynamic photoelastic analysis of stress distribution during preparation of simulated canals with 13 mechanical preparation systems.

Aim: The aim of this study is to compare the stress produced on the internal walls of simulated canals by nine rotary and four reciprocating systems.

Methodology: Sixty-five isotropic transparent blocks containing a 60° curved and tapered simulated canal were selected and distributed into 13 groups (n = 5) according to the preparation system: BioRace, HyFlex EDM, iRaCe, Mtwo, One RECI, ProTaper Next, RaCe EVO, Reciproc, Reciproc Blue, R-Motion, VDW.ROTATE, XP-Endo Rise Shaper, and XP-Endo Shaper.