Session Index

We demonstrate a laser that is prohibited to emit at a particular wavelength, called a dark line, in the emission background of its gain spectrum. The dark line laser is generated from the high-loss resonances of a 150-μm thick etalon mirror in an ytterbium doped fiber laser.

 

We numerically analyzed the bound states in the continuum (BICs) in 1D periodic metallic bar structures and found the accidental BICs. By changing the parameters of the metal structure, we verify the topological nature of the BICs which move along the Brillouin zone and persist under fine-tuning.

 

We demonstrated the NH3 gas sensing by means of DFB tunable laser coupled with a photoacoustic cell near 1550 nm. The detection limit of NH3 was estimated to be 25 ppm. Furthermore, in the flowing system, the noise can be restrained by using differential photoacoustic detection.

 

In this study, the spherical aberration is eliminated via a free-form phase correction function designed by using Zemax. In the measurement, we add the phase function into a SLM. The spot size is reduced 23%. In the future, a metasurface for eliminating the aberration will be fabricated and measured.

 

The home-made Shack-Hartmann wavefront sensor (SHWS) returns the coefficients of 8 primary Zernike modes representing the optical aberrations. Based on the identified model of the deformable mirror in the adaptive optics system (AOS), we implement optimized digital controller to rapidly compensate the aberrations and restore the laser focusing spot quality.

 

The authors present holographic recording of slow-motion pictures of light propagation. The motion picture of not only 2D image but also 3D image of light propagation with the temporal resolution of 96 femtoseconds are demonstrated.