Low Voltage, High Optical Power Handling Capable, Bulk Compound Semiconductor Electro-Optic Modulators at 1550 nm

Abstract

AlGaAs bulk electro-optic Mach-Zehnder modulators with low V  are reported. Epilayer design is an npin, which is shown to be equivalent to a pin. Measured V  is 1 V for 1 cm long electrode and this result agrees very well with numerical modeling. Modulator capacitance remains constant and current through the device is negligible over a wide bias range. Lowest bandgap of the material in the active waveguide region is larger than twice the photon energy at 1550 nm significantly reducing material absorption, including two-photon absorption. Modulator characteristics remain unchanged under coupled input optical powers approaching 160 mW. Low V  combined with high optical power handling capability make these devices suitable for analog photonic links.

High-Performance Mach–Zehnder Modulator Based on Thin-Film Lithium Niobate with Low Voltage-Length Product

“…Generally, materials, such as III–V compounds, conventional bulk lithium niobate (LN), and silicon, have already been widely used to fabricate commercial modulators. However, because of intrinsic nonlinearity, high cost, and the limitation of traditional waveguide fabrication techniques, neither III–V compounds nor bulk LN-based EOMs can meet the large-scale integration and low-cost requirements for the next-generation optical communication systems. − Thanks to the matured complementary metal-oxide-semiconductor (CMOS) fabrication process, silicon has become a major photonics platform but with the highest 3-dB E-O bandwidth only around 60 GHz due to the physical limitation of a free carrier dispersion effect. , Nowadays, with the success of manufacturing thin-film lithium niobate (TFLN) and its breakthroughs in nanofabrication techniques, − the TFLN platform offers new possibilities for high-performance integrated nanophotonic systems. Therefore, EOMs based on the Pockels effect in TFLN have already outperformed their counterparts realized in traditional platforms. , …”

Breaking voltage-bandwidth limits in integrated lithium niobate modulators using micro-structured electrodes

“…For example, V π = 1.5 V and 80 GHz 3-dB bandwidth has been achieved on a differential RF drive architecture [4]. In addition, sub-volt single-drive modulators have also been achieved with 67 GHz 6-dB bandwidth on III-V platforms [5], but the extinction ratio was limited to 3 dB and drive voltage needed to be increased in order to accommodate higher optical power [6]. Organic polymer modulators have shown excellent voltage-bandwidth performances [7] but often the performances need to be compromised in order to improve stability for practical uses [8].…”