Photonic Crystal Surface Emitting Lasers with Naturally Formed Periodic ITO Structures

We have successfully demonstrated GaAs-based photonic crystal surface emitting lasers with low threshold current density of 0.45 kA/cm ² by increasing the thickness of indium-tin-oxide (ITO) top cladding layer appropriately. The thicker ITO top cladding layer contributes to lower scattering loss at the surface and more uniform carrier injection. Furthermore, periodic patterns are formed naturally on the surface of ITO layer during the deposition process, resulting in the deflection of the output beam with an angle of 4.5° from the vertical direction and maintaining a small divergence angle. The turn-on voltage, series resistance, and slope efficiency of the laser pumped at room temperature are 2.09 V, 5.10, and 0.24 W/A, respectively. Lasing wavelengths of different laser devices can be varied from 913.3 to 954.4 nm with several lattice constants designed from 265 to 280 nm. Based on the simple fabrication process, great energy efficiency, small divergence output, and possible beam steering capability by adjusting the periodicity of top cladding layer, such kind of lasers have great potential to be applied in the field of 3D optical sensing, such as vehicle light detection ad ranging, facial identification, environmental sensing, and so on.