In this contribution, we present experimental results of our research on frequency-doubled semiconductor lasers emitting in the visible spectral range. These lasers include a laserdiode pumped semiconductor laser chip in an extended resonator configuration with a critically phase-matched lithium triborate crystal. The use of a single-plate Lyot filter within the cavity leads to single-peak emis...

We perform ray and wave simulations of passive and active spiral-shaped optical microcavities, comparing our results to experimental data obtained with mid-infrared quantum cascade spiral microlasers. Focusing on the angular emission characteristics, we find that both ray and wave simulations are consistent with the experimental data, showing richly-featured, multidirectional far-field emission...

The generation of high intensity coherent radiation m the soft X-ray region from a free electron laser will require the FEL to operate in the high gam or collective instability regime. In this mode of operation, which does not require a cavity resonator, the radiation field grows exponentially along the undulator until nonlinear effects bring on saturation . We discuss the conditions that the e...

The self-consistent integral equation for the field distribution of the resonant modes in a resonator with a tilted retroreflecting corner cube mirror is solved. The corner cube acts like a convex lens with radius of curvature -L cot(2)theta in the rotation direction (L is the cavity length and theta the rotation angle) and like a flat plane in the direction of the rotation axis. The field dist...

We measure optical absorption in color-producing enzymatic reactions for biochemical analysis with a microscale optofluidic device. Cavity-enhanced laser spectrophotometry is performed on analytes within a microfluidic channel at visible wavelengths with silicon nitride microring resonators of 100 µm radius and quality factor of ~180,000. The resonator transmission spectrum is analyzed to deter...

The design and operation of a proof-of-principle rectangular He-Ne ring laser resonator with a cavity perimeter of 77.0 m and an area of approximately 367 m2 are described. With unevacuated beam lines this device gave an Earth-induced Sagnac frequency of 1513 Hz, with a relative Allan deviation over 1000 s down to 3 parts per million. The Earth's rotation provided a bias that eliminated the loc...

By utilizing a racetrack resonator topography, an on-chip mode locked silicon evanescent laser (ML-SEL) is realized that is independent of facet polishing. This enables integration with other devices on silicon and precise control of the ML-SEL's repetition rate through lithographic definition of the cavity length. Both passive and hybrid mode-locking have been achieved with transform limited, ...

We present a detailed theoretical analysis for the determination of the total internal loss in Fabry-Perot resonators based on Fourier analysis of the emission or transmission spectrum. The observation of higher-order harmonics and their relative height in the Fourier-transformed spectrum allow us to quantify the total resonator loss. Because this new method considers both contrast and shape of...

Laterally periodic resonators, which can be constructed by use of transversely periodic phase- or amplitude-modulating elements in a cavity, are proposed for stabilization and generation of transversely coherent output from large-area gain. Lasers with periodic resonators have the combined features of conventional cavities and laser arrays. Significant low-order transverse modes and mode discri...

We report the extension of broadband degenerate OPO operation further into mid-infrared. A femtosecond thulium fiber laser with output centered at 2050 nm synchronously pumps a 500-μm-long crystal of orientation patterned GaAs providing broadband gain centered at 4.1 µm. We observe a pump threshold of 17 mW and output bandwidth extending from 2.6 to 6.1 µm at the -30 dB level. Average output po...