Feedback enhancement in lasers with organic gain material

The mode coupling of organic distributed feedback lasers is enhanced by using a distributed feedback grating that is etched into a thin layer of titanium dioxide (TiO2). The use of TiO22 increases the index contrast in the grating and the confinement in the waveguide. The enhanced mode coupling results in larger feedback given to the lasing modes, which lowers the laser threshold and allows smaller devices to be built. The lasing threshold of the TiO2-enhanced devices is twice as low as that of conventional devices whose grating is etched directly into the quartz.