  Large size single crystals of potassium L-ascorbate monohydrate (KLAM),
(KC6H7O6.H2O) are grown using solution growth technique by lowering the
temperature at the rate of 0.24 {\deg}C/h, where water was used as solvent. The
structure of KLAM was solved by single crystal XRD. KLAM crystallizes in
non-centrosymmetric, monoclinic, P21 space group with lattice parameters a =
7.030(5) {\AA}, b = 8.811(5) {\AA}, c = 7.638(5) {\AA} and \b{eta} =
114.891(5){\deg}. The crystal grows with bulky morphology in all three
directions having (100), (-100), (-110), (0-1-1), (0-11), (001) and (00-1)
prominent faces. TGA and DSC measurements show that KLAM is stable up to 80
{\deg}C. The crystal shows good optical transparency with a lower cut off as
low as 297 nm. Second harmonic conversion efficiency measured on powder sample
is 3.5 times that of potassium dihydrogen phosphate (KDP). Phase matching (PM)
is observed on a plate of the KLAM. Noncollinear phase matching rings are also
observed near the PM directions which help to identify the locus of PM
directions. Presence of noncollinear SHG rings up to third order suggests large
birefringence and nonlinear optical coefficients. Laser damage threshold value
of the crystal is found to be 3.07 GW/cm2, at 1064 nm in 100 direction.

Materials Science