Low-Power-Driven and Low-Optical-Loss 40-Gb/s Electroabsorption Modulator Using Self-Aligned Two-Step Undercut-Etched Waveguide

Abstract

In this letter, a high-efficiency low-power-driven 40-Gb/s electroabsorption modulator is demonstrated using a new type of waveguide, i.e., self-aligned two-step undercut-etched waveguide (SATSUEW). The low-optical-and-electrical-loss performance can be realized from the smooth side wall, wide ridge, and small core of SATSUEW, enabling high-efficiency high-speed optical modulation. Through a 350-μm-long waveguide, 35-dB extinction ratio and 25-dB/V dc modulation efficiency are observed, while optical insertion loss is kept at −6.5 dB (transmission loss of 1 dB/100 μm). A 40-Gb/s operation using 1-Vpp ac driving power with 13-dB extinction ratio is attained, further verified by 55-GHz electrical-to-optical response. The simulated 40-Gb/s eye diagram using distributive effect exhibits a consistent result with the experiment, suggesting that long SATSUEW can be applied to high-bit-rate and high-efficiency operation and thus relaxing the requirements of material and structure in high-speed optoelectronics.

Design and fabrication of optical electroabsorption modulator for high speed and high efficiency

“…Furthermore, wide p-cladding layer and narrow MQW result in both low cladding impedance and low active region capacitance, reducing the microwave loss. Through such technique, bandwidth of above 55GHz and optical propagation loss of 1dB/100µm have bee attained [6]. Using as long as 350µm long waveguide, 35dB extinction ratio and optical insertion loss of -6.5dB were found, leading to 40Gb/s and A.C. extinction ratio of 13dB under Vpp of 1V driving.…”

“…Due to the waveguide structure of EAM, these factors of designs are typically in the trade off relations, resulting in constrain conditions and also fabrication challenge [3][4][5][6]. Considering high-speed applications, the design of EAM performance mostly depends on two parts: (1) the waveguide structure, (2) the active region.…”