Contact metalens for high-resolution optical microscope in semiconductor failure analysis.

The continuous downscaling of electronic devices requires higher-resolution optical microscopic images for semiconductor failure analysis (FA). However, a part of the diffracted light from the measuring pattern in the silicon (Si) substrate cannot be collected due to the total internal reflection (TIR) at the interface between the Si substrate and air. We propose a metalens suitable for FA that improves resolution of optical microscopic images by collecting beyond the critical angle of TIR at the interface. For the proof of concept, we integrated the fabricated metalens into the optical setup of FA and acquired optical microscopic images of FA that clearly show improved resolution.

PCSEL pumped coupling optics free Yb:YAG/Cr:YAG microchip laser.

The passively Q-switched operation of a cryogenically cooled Yb:YAG/Cr:YAG microchip laser was demonstrated with end pumping by a photonic crystal surface emitting laser (PCSEL). This laser generated 70 µJ/1.7 ns/3.2 kHz pulses with near diffraction limited beam quality (M2=1.1) at 1029.4 nm. There were no coupling optics between the microchip laser crystal and PCSEL, which made the system simple and compact.

Demonstration of a photonic crystal surface-emitting laser pumped Yb:YAG laser.

We developed a cryogenically cooled Yb:YAG continuous wave oscillator directly pumped with a photonic crystal surface-emitting laser (PCSEL). A high slope efficiency of 65.7% was obtained at an output power of 208 mW. The beam quality was close to the diffraction limit, with M2<1.2 in both directions. To the best of our knowledge, this is the first PCSEL pumped solid state laser to be developed.

Effects of non-lasing band in two-dimensional photonic-crystal lasers clarified using omnidirectional band structure.

We investigated the effects of non-lasing bands on the beam patterns in photonic-crystal lasers by evaluating the omnidirectional band structure both experimentally and theoretically. We found that a new, weak dual-streak pattern is occasionally generated around the main lobe of the output beam because of scattering of the lasing beam in the non-lasing bands despite a wavenumber mismatch. This result indicates that we can design the high-quality devices without such a noise pattern. In addition, this evaluation method is expected to be useful for developing various high-functionality PC lasers.