Membrane InGaAsP Mach–Zehnder Modulator Integrated With Optical Amplifier on Si Platform

Abstract

A high-efficiency Mach-Zehnder modulator (MZM) using InGaAsP phase shifters and a semiconductor optical amplifier (SOA) using multiple-quantum-well (MQW) are integrated on Si-waveguide circuits. Membrane structure is easy to optically couple to the widely-used 220-nm-thick Si waveguides, because both layers have comparable effective refractive indices. To integrate different bandgap III-V compound semiconductors; InGaAsP-based MQW for SOA and InGaAsP bulk for MZM, we employ epitaxial regrowth on thin-InP layer that is directly bonded on a silicon-on-insulator (SOI) wafer. Their thicknesses are smaller than the critical thickness (∼430 nm) for epitaxial growth of the InP-based layers bonded on the SOI wafer. This fabrication procedure is beneficial for the wafer-level integration of InP-based devices with different bandgaps on Si-photonic circuits. Furthermore, membrane lateral p-n and p-in diode structures improve the modulation efficiency of the MZM and reduce the power consumption of the SOA due to the high optical confinement factor and small active area. The integrated 300-µm-long SOA and MZM with 500-µm-long phase shifters show a fiber-to-fiber lossless operation with the SOA current of only 24 mA at room temperature. The modulation efficiency of the compact MZM is high enough for eye opening with non-return-to-zero (NRZ) signals from 28 to 40 Gbit/s. By using the SOA to amplify the signals modulated by the MZM, the fiber output power of −3.4 dBm was obtained without any significant pattern effect.

Heterogeneously integrated membrane III-V compound semiconductor devices with silicon photonics platform

“…Schematic diagrams of a device are shown in Fig. 10, where DFB lasers and InP-based phase modulators were connected by Si waveguides including a Si MMI [30,31]. As shown in the cross-sections, the phase modulator had no Si waveguide to increase the optical confinement factor.…”

“…Since the superiority of wafer-scale integration or chip-scale integration depends on the ratio of InP devices in the PIC and how many types of InP devices with different bandgaps are required, the preferred manufacturing procedure depends on the application. Thus, we developed membrane photonic III-V devices on SiO2/Si substrates that can accommodate both [23][24][25][26][27][28][29][30][31][32][33][34][35].…”

Heterogeneous Integration of III–V Materials by Direct Wafer Bonding for High-Performance Electronics and Optoelectronics

“…DWB of III-Vs on Si offers a Si-CMOS-compatible solution for integrated optics with potential for low-cost-high-scalability fabrication. Several optoelectronic devices using wafer bonding have been proposed and demonstrated, from electrically pumped lasers [11], [12], [14], [64]- [70], to modulators [71], [72], amplifiers [73], [74], and PDs with high responsivity or bandwidth [75], [76].…”

50-GHz-Bandwidth Membrane InGaAsP Electro-Absorption Modulator on Si Platform

“…Input light from an optical fiber is first coupled to a silica-based (SiOx) core and then input to a 220-nm-thick and 440-nm-wide Si waveguide through an inversely tapered Si waveguide. The light propagating in the Si waveguide subsequently couples to the EAM through a 40-m-long InP taper, whose taper-tip width is around 100 nm [13]. Thanks to the membrane layer, the aspect ratio of the InP-taper tip is very low, so we can easily fabricate low-loss tapers.…”