  The optical floating zone crystal growth technique is a well-established
method for obtaining large, high-purity single crystals. While the floating
zone method has been constantly evolving for over six decades, the development
of high-pressure (up to 1000 bar) growth systems has only recently been
realized via the combination of laser-based heating sources with an all-metal
chamber. While our inaugural high-pressure laser floating zone furnace design
demonstrated the successful growth of new volatile and metastable phases, the
furnace design faces several limitations with imaging quality, heating profile
control, and chamber cooling power. Here, we present a second-generation design
of the high-pressure laser floating zone furnace, "Laser Optical Kristallmacher
II" (LOKII), and demonstrate that this redesign facilitates new advances in
crystal growth by highlighting several exemplar materials:
${\alpha}$-Fe$_2$O$_3$, $\beta$-Ga$_2$O$_3$, and La$_2$CuO$_{4+{\delta}}$.
Notably, for La$_2$CuO$_{4+{\delta}}$, we demonstrate the feasibility and
long-term stability of traveling solvent floating zone growth under a record
pressure of 700 bar.
