5 x 20 Gb/s heterogeneously integrated III-V on silicon electro-absorption modulator array with arrayed waveguide grating multiplexer

Abstract

Abstract:We present a five-channel wavelength division multiplexed modulator module that heterogeneously integrates a 200GHz channelspacing silicon arrayed-waveguide grating multiplexer and a 20Gbps electro -absorption modulator array, showing the potential for 100 Gbps transmission capacity on a 1.5x0.5 mm 2 footprint. ©2015 Optical Society of America IntroductionWavelength division multiplexing (WDM) modules are of key importance for realizing high aggregate bitrate optical networks and optical interconnects. WDM transmitters and receivers require low cost and high performance devices for maximal bandwidth usage and high energy-efficiency. For the key opto-electronic components in a WDM system, both silicon and III-V based devices are available. Potentially CMOS compatible, low-cost, monolithic silicon WDM modulator chips have been reported [1,2]. However, an optically broadband silicon-based modulator usually has a large footprint and requires a relatively high driving voltage and hence high power consumption for sufficient extinction ratio [3]. Alternatively, purely III-V WDM modulator chips have been demonstrated [4, 5]. Although they are more efficient than silicon modulators, the monolithic integration with passive wavelength division multiplexing devices, e.g. arrayed waveguide gratings (AWG) and etched diffractive gratings (EDG) is not straightforward. In order to overcome these issues, a hybrid silicon platform that combines the advantages of III-V based materials and silicon is being studied. III-V/Si hybrid active devices with excellent performance, such as hybrid silicon narrow linewidth lasers [6], high-speed modulators [7], and high-speed detectors [8] have already been demonstrated. The highest speed modulators on silicon were achieved by transferring a III-V epitaxy stack onto a SOI wafer to realize a 67GHz bandwidth traveling-wave hybrid silicon electro-absorption modulator (EAM) [7]. These hybrid devices can be integrated together to build up more complex on-chip photonic modules [9, 10] on silicon-based substrates, which shows its potential for high density, high performance WDM transmitters and receivers for optical communication networks and multi-CPU optical interconnects in the future.

III-V-on-Silicon Photonic Devices for Optical Communication and Sensing

“…In the case of external modulation, for shorter distance links III-V EAMs are often used. We developed a 5 × 20 Gbps WDM transmitter consisting of an array of 5 EAMs heterogeneously integrated on a silicon PIC used for wavelength multiplexing (using an AWG) and fiber-chip interfacing, operating around 1.55 μm [56]. The lumped III-V EAMs show a 3-dB E/O bandwidth of 17 GHz and can operate up to 28 Gbps.…”

All-optical NRZ wavelength conversion based on a single hybrid III-V/Si SOA and optical filtering

“…Six dB-10 dB insertion losses and 10 dB-15 dB crosstalks were measured for the present (de)multiplexer, where the coupling losses between the fiber and the grating were normalized out. This loss comes partially from the AWG itself (2.5 dB-5 dB, due to imperfections in the fabrication), as well as the insertion losses for the EA sections (2 dB-7 dB) [26], which were fabricated using BCB adhesive bonding technology [31]. The 3-D structure of the EA section is sketched in Fig.…”

“…The III-V layer stack contains InAlGaAs multiple-quantum-wells (MQWs) and two separate confinement heterostructure layers (SCHs) as described in Table 1. We refer to [26] for the detailed structure of the hybrid waveguide as well as the fabrication processes. A picture of the fabricated transceiver chip is shown in Fig.…”

Low driving voltage band-filling-based III-V-on-silicon electroabsorption modulator

“…1,4,8,9 However, for silicon photonics, it is important to reduce the power consumption. Because the transition energy consumed by an EAM is proportional to the driving voltage squared, 1 a low driving voltage EAM is required in silicon photonics.…”

“…4,8,9 Thanks to the highly selective wet etching process used, a photoresist mask instead of a SiN hard mask can be used to define the III-V waveguide. In this way, the deposition and etching of SiN hardmask layers by PECVD and ICP-RIE respectively is avoided.…”