Rewritable photonic integrated circuits

Photonic integrated circuits (PICs) have the potential to drastically expand the capabilities of optical information science and engineering. However, PICs are commonly fabricated using selective material etching, a subtractive process. Thus, the chip's functionality cannot be substantially altered once fabricated. Here, we propose to exploit wide-bandgap non-volatile phase-change materials (PCMs) to create a rewritable PIC platform. A PCM-based PIC can be written using a nano-second pulsed laser, akin to rewritable compact disks. The whole circuit can then be erased by heating, and a completely new circuit can be rewritten. We numerically designed a dielectric-assisted PCM waveguide consisting of a thick dielectric layer on top of a thin layer of wide-bandgap PCMs. The low-loss PCMs and our engineered waveguiding structure lead to negligible optical loss. Furthermore, we analyzed the spatio-temporal laser pulse shape to write the PCMs. Finally, we experimentally demonstrated such a rewritable PIC. Our proposed platform will enable low-cost manufacturing and have a far-reaching impact on the rapid prototyping of PICs, validation of new designs, and photonic education.