  Photonic integrated circuits (PICs) have the potential to drastically expand
the capabilities of optical communications, sensing, and quantum 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
without removing any material, akin to rewritable compact disks. The whole
circuit can then be erased by heating, and a completely new circuit can be
rewritten. We designed a dielectric-assisted PCM waveguide consisting of a
thick dielectric layer on top of a thin layer of wide-bandgap PCMs Sb2S3 and
Sb2Se3. The low-loss PCMs and our engineered waveguiding structure lead to a
negligible optical loss. Furthermore, we analyzed and specified the
spatio-temporal laser pulse shape to write the PCMs. 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.
