Abstract
In this study, we investigated the performance of Si lattice-shifted photonic crystal waveguide (LSPCW) Mach-Zehnder modulators theoretically and experimentally. The LSPCW increases the phase shift in modulator to 2.3 - 2.5 times higher, which allows for size reduction and high performance. On-chip passive loss was reduced to less than 5 dB by optimizing each component. We obtained 25 Gbps clear open eye and 3 dB extinction ratio at a drive voltage of 1.5 – 1.75 V for 200 μm phase shifter with linear p/n junction when we added a modulation loss of 7 dB. This modulation loss was reduced to 0.8 dB, maintaining other performance, by employing interleaved p/n junction and optimizing doping concentrations.
Highlights
Si photonics, which can produce highly integrated photonic circuits using CMOS-compatible process, has been developed extensively toward optical interconnects [1]
Since external light sources are used in current Si photonics, Si modulators based on carrier plasma dispersion (CPD) [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20], electro-absorption [21, 22], or so are necessary
The CPD in p/n diode structures is practically used in commercial modulators for optical interconnects because of the easy fabrication of the p/n junction and operation over the wide range of wavelength and temperature, which is crucial in optical interconnects
Summary
Si photonics, which can produce highly integrated photonic circuits using CMOS-compatible process, has been developed extensively toward optical interconnects [1]. STRUCTURE Figure 2 shows the structure of the LSPCW modulator in this study It consists of two LSPCW phase shifters with p/n junctions at the waveguide center, thermo-optic phase tuners with TiN heaters, and MZ circuit of Si wires. When the depletion region extends, both n [cm−3] and p [cm−3] decrease, leading to a positive nSi. Figure 4A shows the spatial distribution of nSi in the unit cell model of LSPCW (II in Figure 2), when the applied voltage is changed from −0.625 to −2.375 V, which correspond to dc bias voltage VDC = −1.50 V and drive voltage Vpp = 1.75 V in the modulation experiment. Corresponding to the larger depletion region of the interleaved junction #2 and #3, neq increases to 1.7 and 2.0 times that of the linear junction, respectively. We calculated neq for a typical rib waveguide modulator with the central linear junction and middle doping. While ML becomes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
