Compact magneto-optical isolator by mu-transfer printing of magneto-optical single-crystal film on silicon waveguides

Optical isolators provide one-way propagation and are necessary to protect laser diodes from damage and unstable operation caused by reflected light. Although magneto-optical (MO) devices can operate as isolators, achieving high-density integration using conventional direct bonding methods is difficult because a large and thick growth substrate remains on the circuits. We experimentally demonstrated a compact Mach-Zehnder interferometer-based MO isolator with Si waveguides by the mu-transfer printing of a Ce:YIG/SGGG coupon. The isolator has a footprint of 0.25 mm(2) with a Ce:YIG/SGGG coupon of 50 x 800 mu m(2) and similar to 1-mu m thickness and achieved a maximum isolation ratio of 14 dB in telecom bands.

Automated summary

Optical isolators are important for safeguarding laser diodes from damage caused by reflected light, and achieving high-density integration with conventional methods has been challenging. However, the use of mu-transfer printing of a Ce:YIG/SGGG coupon has allowed for the experimental demonstration of a compact MO isolator based on a Mach-Zehnder interferometer with Si waveguides. This isolator has a small footprint, a thickness of approximately 1 μm, and achieved a maximum isolation ratio of 14 dB in telecom bands.