  We have developed the laser-diode-heated floating zone (LDFZ) method, in
order to improve the broad and inhomogeneous light focusing in the conventional
lamp-heated floating zone method, which often causes difficulties in the
crystal growth especially for the incongruently melting materials. We have
simulated the light focusing properties of the LDFZ method to make irradiated
light homogeneous and restricted mostly to the molten zone. We have designed
and assembled an LDFZ furnace, and have demonstrated how it works through
actual crystal growth. The method is applicable to various kinds of materials,
and enables stable and reproducible crystal growth even for the incongruently
melting materials. We have succeeded in the crystal growth of representative
incongruently melting materials such as BiFeO3 and (La,Ba)2CuO4, which are
difficult to grow by the conventional method. Tolerance to the decentering of
the sample and highly efficient heating are also established in the LDFZ
method.
