  Above cryogenic temperatures, random laser (RL) emission under continuous
wave (CW) optical pumping is often challenging for materials having plenty of
lattice defects. Thus, intensive care is required while fabricating the RL
device. Synthesis of 2D materials having unique functionality at the atomic
limit is necessary for use in such devices. In this work, defects-free 2D
yellow pearl (2D-YP) has been synthesized from bulk south sea pearl using
liquid-phase exfoliation (LPE) technique. Thereafter, 2D-YP has been employed
as passive scatterer to achieve CW pumped RL emission from a conventional gain
molecule, i.e., Rhodamine B (RhB). Compared to other semiconductor (TiO2) and
2D (Graphene and h-BN) passive scatterers, ~25 times improvement in gain volume
is observed for the disordered system consisting of RhB and 2D-YP, i.e.,
2D-YP@RhB, which is found to be due to the formation of a large refractive
index gradient, as induced by the thermal nonlinear optical (NLO) interaction.
Hence, incoherent RL (ic-RL) emission ~591 nm is reported for 2D-YP@RhB at a
lowest threshold input pump power and a linewidth of 65 mW and 3 nm,
respectively. Additionaly, a clear transition from ic-RL to mode tunable
coherent RL (c-RL) emission is also possible by altering the configuration of
the 2D-YP@RhB container. Therefore, the newly designed Van der Waals
heterostructure, i.e., 2D-YP with intrinsic photon trapping capability may pave
an avenue towards developing future exciting optoelectronic devices.
