Open AccessIntegration of a high-efficiency Mach-Zehnder modulator with a DFB laser using membrane InP-based devices on a Si photonics platform
Author(s) -
Tatsurou Hiraki,
Takuma Aihara,
T. Fujii,
Koji Takeda,
Yoshiho Maeda,
Takaaki Kakitsuka,
Tai Tsuchizawa,
Shinji Matsuo
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.411483
Subject(s) - materials science , extinction ratio , optoelectronics , diode , phase shift module , photonics , mach–zehnder interferometer , wafer , optics , waveguide , laser , modulation (music) , phase (matter) , substrate (aquarium) , phase modulation , insertion loss , interferometry , phase noise , wavelength , chemistry , physics , acoustics , organic chemistry , oceanography , geology
We demonstrate a wafer-level integration of a distributed feedback laser diode (DFB LD) and high-efficiency Mach-Zehnder modulator (MZM) using InGaAsP phase shifters on Si waveguide circuits. The key to integrating materials with different bandgaps is to combine direct wafer bonding of a multiple quantum well layer for the DFB LD and regrowth of a bulk layer for the phase shifter. Buried regrowth of an InP layer is also employed to define the waveguide cores for the LD and phase shifters on a Si substrate. Both the LD and phase shifters have 230-nm-thick lateral diodes, whose thickness is less than the critical thickness of the III-V compound semiconductor layers on the Si substrate. The fabricated device has a 500-µm-long DFB LD and 500-µm-long carrier-depletion InGaAsP-bulk phase shifters, which provide a total footprint of only 1.9 × 0.31 mm 2 . Thanks to the low losses of the silica-based fiber couplers, InP/Si narrow tapers, and the phase shifters, the fiber-coupled output power of 3.2 mW is achieved with the LD current of 80 mA. The MZM has a V π L of around 0.4 Vcm, which overcomes the V π L limit of typical carrier-depletion Si MZMs. Thanks to the high modulation efficiency, the device shows an extinction ratio of 5 dB for 50-Gbit/s NRZ signal with a low peak-to-peak voltage of 2.5 V, despite the short phase shifters and single-arm driving.