Vacuum ultraviolet second-harmonic generation in NH₄B₄O₆F crystal

Area of Science:

• Materials Science
• Optics and Photonics
• Solid State Chemistry

Background:

• Vacuum ultraviolet (VUV) light sources (100-200 nm) are essential for spectroscopy, quantum research, and semiconductor lithography.
• Second-harmonic generation (SHG) using nonlinear optical (NLO) crystals is the most efficient method for VUV generation.
• Existing NLO crystals face limitations in phase-matching, efficiency, and crystal growth, hindering VUV production.

Purpose of the Study:

• To develop a novel NLO crystal material for efficient VUV light generation.
• To overcome the limitations of current NLO crystals in VUV applications.
• To explore the potential of fluorooxoborate compounds for advanced optical applications.

Main Methods:

• Synthesis and characterization of the fluorooxoborate crystal NH4B4O6F (ABF).
• Fabrication of VUV devices utilizing ABF with specific phase-matching angles.
• Experimental measurement of VUV light generation via phase-matching SHG.

Main Results:

• Achieved a record VUV wavelength of 158.9 nm through phase-matching SHG using ABF.
• Generated a maximum nanosecond pulse energy of 4.8 mJ at 177.3 nm.
• Attained a VUV conversion efficiency of 5.9% attributed to the crystal's asymmetric sublattice structure.

Conclusions:

• NH4B4O6F (ABF) is a highly promising NLO material for VUV generation.
• The crystal's structure facilitates enhanced NLO performance, meeting phase-matching requirements.
• ABF holds potential for developing compact, high-power VUV lasers.