Fundamental characteristics and high-speed applications of carrier-depletion silicon Mach-Zehnder modulators

Abstract

Carrier-depletion Si Mach-Zehnder modulators incorporating lateral PN-junction phase shifters are reviewed in the lights of fundamental characteristics and applications to high-speed optical fiber transmission. Experimental reverse-bias characteristics are supported by numerical analysis with good agreement, implying that the Si modulators are fabricated precisely as designed. Numerical high-speed response proves that the phase shifter operates beyond 100-Gbaud symbol rate. Traveling-wave electrodes are characterized in S-parameter measurements to reveal LRC resonance as a limiting factor in high-speed modulation. High-speed optical-fiber transmission in on-off and phase-shift keying formats is demonstrated using the Si Mach-Zehnder modulators assembled in ceramic-based metal packages.

Silicon optical modulator simulation

“…In this case, both methods are used to analyze both mod1 and mod2 and the give very similar results and agrees well with [11,15,34] which verifies that our implementation is correct. For clarity, results obtained from finite difference method are discussed.…”

“…In this work, eye diagram is generated by simulating the behavior of a single drive Mach-Zehnder Modulator (MZM) with random bit sequence. Our simulated eye diagram at 10-Gb/s NRZ OOK has demonstrated and verified against experimental data [34] with good agreement.…”

Silicon-based phase shifters for high figure of merit in optical modulation

“…Experimental DC reverse-bias voltage dependences of phase shift and carrier-induced optical loss were obtained by optical transmission measurements for the Si MZMs with swept DC reverse-bias voltage. 4 For theoretical characteristics, two-dimensional device simulation based on a finite-element solver for charge continuity and carrier transport equation combined with Poisson equation was performed to obtain numerical carrier distribution profiles in the lateral PN-junction phase shifters under DC reverse-bias voltages. 16 Electron and hole concentrations in N-and P-type areas are 2x10 17 cm -3 and 5x10 17 cm -3 , respectively.…”

“…[2][3][4][5][6][7][8][9][10][11] In telecom applications, in particular, high-speed optical modulation beyond 100 Gb/s/λ for optical-fiber transmission in advanced modulation formats such as dual-polarization quadrature phaseshift keying (DP-QPSK) has been achieved by using lateral PN-junction carrier-depletion silicon MZMs, which were monolithically integrated with optical circuits such as waveguides for polarization-division multiplexing (PDM) on a silicon-on-insulator (SOI) wafer in small chip footprints. [2][3][4][5] Optical-fiber transmission up to 1000 km in 128-Gb/s DP-QPSK format has been demonstrated by using the monolithic silicon PDM IQ MZM copackaged with electrical modulator drivers in a ceramic-based metal package in a small form factor of 15x35 mm 2 in footprint and 4.5 mm in profile. 4,12 Peak-to-peak RF voltage (RF V PP ) of ~6.5 V or higher in 50-ohm impedance matching produces 180-degree phase shift in the silicon MZM, and further reduction in the drive voltage is required for the deployment of the compact silicon modulator in energy-efficient optical transport networks.…”

“…[2][3][4][5] Optical-fiber transmission up to 1000 km in 128-Gb/s DP-QPSK format has been demonstrated by using the monolithic silicon PDM IQ MZM copackaged with electrical modulator drivers in a ceramic-based metal package in a small form factor of 15x35 mm 2 in footprint and 4.5 mm in profile. 4,12 Peak-to-peak RF voltage (RF V PP ) of ~6.5 V or higher in 50-ohm impedance matching produces 180-degree phase shift in the silicon MZM, and further reduction in the drive voltage is required for the deployment of the compact silicon modulator in energy-efficient optical transport networks. This paper focuses on latest progress in experimental and theoretical studies on silicon rib-waveguide carrier-depletion phase shifters having various PN-junction configurations in the light of high modulation efficiency for energy-efficient photonic networks of high-transmission capacity.…”