Atomic layer deposition-enabled few-mode erbium-doped waveguide amplifiers with low differential mode gains

Area of Science:

• Photonics and Optical Engineering
• Materials Science for Integrated Optics

Background:

• Few-mode waveguide amplifiers are crucial for optical communication systems.
• Achieving high gain and low differential mode gain (DMG) simultaneously is a key challenge.

Purpose of the Study:

• To present a novel and efficient methodology for high-gain, low-DMG on-chip few-mode erbium-doped waveguide amplifiers.
• To theoretically model and experimentally validate the gain performance across multiple optical modes.

Main Methods:

• Utilized an optimized algorithm to model gain performance for six lowest-order optical modes (TE0, TM0, TE1, TM1, TE2, TM2).
• Proposed a fabrication process integrating atomic layer deposition (ALD) with complementary metal-oxide semiconductor (CMOS) techniques.

Main Results:

• Achieved internal net gains exceeding 22 dB for six signal modes within a 5-cm waveguide.
• Maintained a low differential mode gain (DMG) of only 2 dB, a 5 dB reduction compared to uniform doping.
• Demonstrated a maximum saturated output power of 150 mW.

Conclusions:

• The proposed methodology significantly enhances the performance of few-mode optical waveguide amplifiers.
• The optimized doping approach offers superior gain and mode uniformity.
• Feasible fabrication process enables practical implementation of advanced on-chip amplifiers.