Intra-cavity Mode Selection Research Articles

SESAM-based mode-locked vortex Ti:sapphire laser using spot-defect spatial filter for intra-cavity mode selection

In virtue of the significance of ultrashort vortex pulses, a mode-locked LG01-mode vortex Ti:sapphire laser is first realized. In the study, an intra-cavity spot-defect spatial filter was used to suppress the TEM00 mode’s oscillation and a semiconductor saturable absorber mirror was used as the mode-locked device. As a result, the mode-locked laser emitted LG01-mode vortex pulses of 186 ps at 804.4 nm with a repetition rate of 78.95 MHz and a maximum average output power of 176 mW. The phase of the LG01 mode was measured by a Mach–Zehnder interferometer and both right- and left-handed helical wavefronts were obtained.

基于腔内选模的全固态涡旋激光器及手性控制

基于腔内选模的全固态涡旋激光器及手性控制

Swept source optical coherence tomography using an all-fiber 1300-nm ring laser source

The increased sensitivity of spectral domain optical coherence tomography (OCT) has driven the development of a new generation of technologies in OCT, including rapidly tunable, broad bandwidth swept laser sources and spectral domain OCT interferometer topologies. In this work, the operation of a turnkey 1300-nm swept laser source is demonstrated. This source has a fiber ring cavity with a semiconductor optical amplifier gain medium. Intracavity mode selection is achieved with an in-fiber tunable fiber Fabry-Perot filter. A novel optoelectronic technique that allows for even sampling of the swept source OCT signal in k space also is described. A differential swept source OCT system is presented, and images of in vivo human cornea and skin are presented. Lastly, the effects of analog-to-digital converter aliasing on image quality in swept source OCT are discussed.

Diffractive optical elements for intra-cavity beam-shaping of laser modes

Diffractive optical elements (DOE) are applied as intra-cavity mode selection devices for customizing the fundamental mode of laser resonators for high power laser systems. Using a phase-conjugating mode selecting element (MSE) in a laser oscillator, we are able to produce a good approximation to a super-Gaussian mode with a near flat intensity profile. This offers higher energy extraction from any following laser amplifiers compared to an unmodified Gaussian TEM00 mode. Two different designs for operation in a 1 m cavity length Nd:YAG master oscillator are presented. Both designs are surface relief phase elements fabricated in fused silica using photolithography with reactive-ion etching to produce 16 level elements for use in transmission. One element is designed to replace the cavity end mirror, while the other stands off an arbitrary distance from the end mirror. A novel iterated design for these transmissive elements is introduced. Numerical results and experimental measurements are presented and discussed.

Birefringent beam splitter for intracavity mode selection in high-power multimirror lasers

The design and application of an uncoated sapphire plate that acts as both the beam splitter and the output coupler of an interferometric laser resonator are described. Output coupling is provided at one of the surfaces by p-polarized (TM) reflection near the Brewster angle, and axial-mode selection is enforced at the other surface by s-polarized (TE) reflection at the same angle of incidence. The design is discussed in the context of the phase-locked, rf linac free-electron laser, in which the coupling of adjacent optical pulses at the beam splitter induces temporal phase coherence among all the pulses in the output beam; this coherence is manifested in the frequency domain as a reduction in the number of axial modes per rf frequency interval. The Michelson and Fox-Smith resonator designs are compared, and applications to cavity dumping are discussed.

Erbium-doped fiber compound-ring laser with a ring filter

A new all-fiber, diode-pumped laser with a compound-ring structure has been demonstrated. A double-coupler fiber ring filter formed by two in-line low-loss couplers is used as an intracavity mode selection element. It functions as a filter which provides a larger free spectral range for the compound laser cavity and serves as a ready port for the laser output. The fiber laser is pumped at 980 nm with a threshold of 7.9 mW and a slope efficiency of 0.11. The condition for a maximum output power can be obtained by tuning an in-line polarization controller.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>