Three-port optical phase-shifters and modulators with ultra-high modulation efficiency, positive RF-Linking gain, and low residual amplitude modulation

Rui Lin Chao, Zohauddin Ahmad, Jye-Hong Chen, Yin-Chieh Lai, Jin Wei Shi*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

A three-port optical phase-shifter and Mach-Zehnder modulator (MZM) based on PNP-type bipolar junction transistor (BJT) is demonstrated. Significant plasma (injected carrier) induced changes of the refractive index for the optical waveguide become possible with an extremely small driving-voltage and a compact device size during operation of this BJT between the saturation and forward active modes. Devices with a standard MZM structure and a small foot-print (0.5 mm) exhibit a moderate optical insertion loss (2 dB), extremely small Vπ (0.18V) and Pπ (0.21mW), fast rise/fall time ( 1ns), and a residue-amplitude-modulation (RAM) as small as 0.18 dB. Furthermore, thanks to the ultra-high modulation efficiency characteristic of our device, a +4.0 dB net RF-linking gain can be obtained under dynamic operation. Compared to 2-port (base-collector) forward bias operation, under three-port operation, the extra bias current from the base-emitter junction provides a lower Vπ (0.18 vs. 0.22 V), a smaller RAM (0.18 vs. 0.6 dB), and a larger RF-linking gain (+4 vs. -3.2 dB). The superior performances of the three-port to two-port operations can be attributed to the additional forward bias B-E junction being able to provide more injected carriers to induce stronger plasma effects for optical phase-shifting.

Original languageEnglish
Article number9079834
Pages (from-to)80836-80841
Number of pages6
JournalIEEE Access
Volume8
DOIs
StatePublished - 28 Apr 2020

Keywords

  • Optical phase shifter
  • photonics integrated circuits
  • RF-linking gain
  • silicon photonics

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