The basic structure of iPMSELs is similar to that of ordinary laser diodes. A novel phase modulating layer is introduced near the active layer. The holes in the phase modulating layer are systematically arranged in positions slightly shifted from the lattice point of square-lattice photonic-crystal. The layer contributes to two important operating mechanisms, “in-plane resonance” due to zero-group velocity at the photonic-band edge and “spatial-phase modulation” of output beam patterns due to the positional shift of holes designed using computer generated holograms. However, the prototype device shows not only target beam patterns but also subsidiary beam patterns including a strong central spot beam (zero order beam) attributable to vertical diffraction.
To address the issue, we improved the design and successfully removed the beam, demonstrating periodic beam patterns useful for 3D measurements. We also present a demonstration of electrical switching of beam patterns using arrayed iPMSELs where eight devices are integrated onto a TO-8 base. This enables applications including beam scanning or indications.