TY - JOUR
T1 - Three-port optical phase-shifters and modulators with ultra-high modulation efficiency, positive RF-Linking gain, and low residual amplitude modulation
AU - Chao, Rui Lin
AU - Ahmad, Zohauddin
AU - Chen, Jye-Hong
AU - Lai, Yin-Chieh
AU - Shi, Jin Wei
PY - 2020/4/28
Y1 - 2020/4/28
N2 - 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.
AB - 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.
KW - Optical phase shifter
KW - photonics integrated circuits
KW - RF-linking gain
KW - silicon photonics
UR - http://www.scopus.com/inward/record.url?scp=85084957743&partnerID=8YFLogxK
U2 - 10.1109/ACCESS.2020.2990956
DO - 10.1109/ACCESS.2020.2990956
M3 - Article
AN - SCOPUS:85084957743
SN - 2169-3536
VL - 8
SP - 80836
EP - 80841
JO - IEEE Access
JF - IEEE Access
M1 - 9079834
ER -