Experimental Demonstration of Multi-Bit Optical Buffer Memory Using 1.55- $\mu{\hbox {m}}$ Polarization Bistable Vertical-Cavity Surface-Emitting Lasers

We demonstrate a novel all-optical buffer memory using 1.55-μm polarization bistable vertical-cavity surface-emitting lasers (VCSELs). A one-bit data is stored as one of two orthogonal polarization states of a VCSEL in this memory. The polarization state is transferred from the VCSEL to another VCSEL which is optically connected in cascade as a shift register. A 4-bit optical buffer memory is constructed using two sets of the shift-register memory connected in parallel. These results show the technical feasibility of multi-bit optical buffer memory.