On-Chip Electro-Optic Modulator With Loss Compensation Based on Polymeric Active-Integrated Waveguides

Meiling Zhang,Xibin Wang,Guijun Hu

doi:10.1109/access.2020.3003676

Abstract

In this paper, an on-chip electro-optic (EO) modulator with loss compensation based on polymeric active-integrated waveguides was demonstrated. An erbium-doped waveguide amplifier was investigated and integrated with the EO modulator to compensate for signal loss. Polymeric active-integrated waveguides were based on the Mach-Zehnder interferometer structure, which consists of an amplified waveguide formed by two symmetric Y-junction branches and an EO waveguide formed by two decoupled waveguide arms. The dimensions of the polymeric active-integrated waveguides and the modulator were carefully designed and simulated. Moreover, a six-level spectroscopic model pumped at 980 nm was presented. The rate equations and propagation equations were solved, and the gain characteristics were simulated. The internal gain of 4.65 dB was achieved when the signal power was 0.1 mW at 1550 nm, the pump power was 100 mW at 980 nm, the Er 3+ concentration was $9.3\times 10^{25}/\text{m}^{3}$ , and the Yb 3+ concentration was $8.6\times 10^{26}/\text{m}^{3}$ in one Y-junction branch with a length of 1.5 cm. With the integrated waveguide amplifier, the loss of the EO modulator can be compensated at 9.3 dB in the two symmetric Y-junction branches. The light output intensity was also statistically presented. The proposed device with active-integrated waveguides could be used in polymer-based photonics integrated circuits.

Highlights

Integrated optical waveguide devices are gradually becoming key components in optical telecommunication network systems [1]–[3]
The optical switches, and optical modulators play an indispensable role in wavelength division multiplexing (WDM) technology which serves as an important component of optical add-drop multiplexer (OADM) and optical cross-connection (OXC) applications [9], [10]
High insertion losses mainly occur from the coupling loss between the optical fiber and the waveguide, the scattering losses caused by fabrication, and the absorption loss from chromophores, which affect the performance of the EO modulator and impede the development of the devices

Summary

INTRODUCTION

Integrated optical waveguide devices are gradually becoming key components in optical telecommunication network systems [1]–[3]. High insertion losses mainly occur from the coupling loss between the optical fiber and the waveguide, the scattering losses caused by fabrication, and the absorption loss from chromophores, which affect the performance of the EO modulator and impede the development of the devices. Erbium-doped waveguide amplifiers (EDWAs) are vital components for solving this problem because the infrared emission wavelength of the Er3+ ion corresponds to the low-loss telecommunication window in the wavelength range of approximately 1550 nm in optical communications [26]–[28]. Combined with the excellent properties of polymer such as simple processing, flexible design of optical properties and compactness, EDWA was investigated and integrated with an EO modulator to compensate for signal loss. A new method for solving the bottleneck problem that high insertion loss limits the performance of the EO devices was provided, especially for integrating them into photonics integrated circuits.

DEVICE DESIGN AND SIMULATION

ANALYSIS OF EO MODULATION PERFORMANCE

CONCLUSIONS