The properties of NPC structures in strontium tetraborate are analyzed. Different types of NPC structures are revealed
that possess different nonlinear properties, and their spectral dependences of frequency conversion efficiency are
calculated and compared. Experimental study of these structures is reported for the process of doubling of the second
harmonic of fs Ti:S laser. Tuning of generated radiation is obtained in the range 187.5 - 232.5 nm, with extreme
insensitivity to the angular orientation of NPC. Behavior of tuning curve along investigated fundamental wave range is
similar in all studied samples, but efficiency obtained depends on the type of structure. Conversion efficiency and
spectral quality of generated radiation is experimentally shown to grow better when using NPC with improved structure.
Prospects of VUV converter on a single NPC are discussed. NPCs of SBO are demonstrated to be useful for
autocorrelation diagnostics both in random QPM geometry and in the geometry of nonlinear diffraction from virtual
Random quasi-phase-matched frequency doubling of fs pulses to the deep UV was obtained in 1D nonlinear photonic
crystal (NPC) of strontium tetraborate. Tuning range of generated radiation is from 187.5 to 215 nm. The spectrum of
generated radiation consists from series of peaks with the width of order of 1 Å. These peaks are the manifestation of the
NPC band structure. Using fs oscillator as the fundamental radiation source, maximum average power of generated
radiation is of order 1 μW, the enhancement factor with respect to monodomain sample being of order of several
hundred. The red rotational shift of NPC band structure is experimentally demonstrated.
Random nonlinear photonic crystal (NPC) structures formed by as-grown domains in a non-ferroelectric strontium
tetraborate (SBO) are investigated. The domain shape and orientation are similar to those in ferroelectric KTP. Nonlinear
diffraction is the simplest way to detect, evaluate and characterize these structures. Reciprocal superlattice vectors
spectra of NPC in SBO are very wide and enable broadband efficiency enhancement of nonlinear optical processes.
Second harmonic (SH) generation of femtosecond Ti:sapphire oscillator radiation with 1.9% efficiency is obtained using
nonlinear diffraction geometry. Random quasi phase matched generation at the wavelengths of fourth harmonic of
Ti:sapphire laser is obtained with average power up to 1μW.