077-V drive voltage electro-optic modulator with bandwidth exceeding 67  GHz

Abstract

A 0.77-V drive voltage (V π ) electro-optic modulator with bandwidth exceeding 67 GHz is described. Modulator is a compound semiconductor device fabricated using substrate removal technology. This allows placement of metal electrodes on both sides of an optical waveguide containing a p-i-n diode. Hence ohmic losses are reduced significantly. Electrode gap is essentially the same as i layer thickness, which can be kept very uniform and small. Waveguide core also contains a MQW, which improves electro-optic efficiency. Lack of p doping in the waveguide and large detuning between MQW absorption peak and operating wavelength keep the propagation loss low. Large size of the waveguide also helps to keep coupling loss low. Modulator is designed as a traveling wave device using the loaded line approach, which is used for velocity matching. Combination of these approaches yields a device with the lowest V π and widest bandwidth.

Intensity and Phase Modulators at 1.55 μm in GaAs/AlGaAs Layers Directly Grown on Silicon

“…Devices reported here are fairly long and high speed operation can be achieved using a traveling wave design. In our previous work, we demonstrated modulators with bandwidth exceeding 40 GHz in similar structures using a loaded line traveling wave electrodes [4]. Therefore, with appropriate design similar bandwidths can be obtained for these devices.…”

“…Their direct band gap enables fabrication of lasers and optical amplifiers at telecommunication wavelengths such as 1.3 μm and 1.55 μm. Lack of inversion symmetry in these compound semiconductors allow electro-optic modulators with significantly better performance [2], [3], [4]. However, these materials are typically grown on InP and GaAs substrates, which are smaller than Si substrates.…”

InP photonic circuits using generic integration [Invited]

“…Industry-produced InP modulators already achieve modulation efficiencies of down to 3.5 V π mm [8]. Further improvements are feasible with the very high optical overlap achieved in substrate-removed devices: values as low as 0.6 V π mm have now been reported under push-pull drive [37,38]. Such substrate-removal techniques also open the way to low electronic parasitics.…”

Dual-function photonic integrated circuit for frequency octo-tupling or single-side-band modulation

“…While LiNbO 3 technology offers a mature solution to the small scale integration of MZM structures, this work anticipates photonic integrated circuits based on Si and/or InP material integration platforms emerging as the preferred choice for photonic integration [15]. In this context, the continuous advances made in improved speed, linearity, footprint, and energy consumption of electro-optic phase modulator devices in both material platforms [16][17][18] bodes well. Figure 1 provides a schematic diagram of a circuit capable of the dual function of either millimeter wave carrier generation by frequency octo-tupling a microwave RF input carrier or frequency up-conversion to the optical domain of an RF input carrier in the electronic domain by carrier-suppressed SSB modulation, the latter being equivalent to the modulation of an optical carrier by baseband in-phase and quadrature (I&Q) signals.…”

“…The SSB operation can be performed for a wide range of modulation index, while the frequency octo-tupling is achieved by carefully adjusted modulation index. Finally, mature fabrication platforms for MMIs and continuous improvements demonstrated performance of phase modulators based on silicon, III-V [16], or semiconductor-organic hybrid technologies [17,18] makes the implementation of the dual-function photonic integrated circuit practical. A comprehensive review of the circuit's applications may be found in [15].…”