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[IEEE 2019 International Topical Meeting on Microwave Photonics (MWP) - Ottawa, ON, Canada (2019.10.7-2019.10.10)] 2019 International Topical Meeting on Microwave Photonics (MWP) - Impact of Nonlinearity on RF-Modulated Frequency Combs with Different Modulation Depths in an MUTC Photodetector
摘要： We calculate the impact of nonlinearity in a modi?ed uni-traveling carrier (MUTC) photodetector on an RF-modulated frequency comb that is generated using short optical pulses. We take into account bleaching (nonlinear saturation), which plays an important role due to the large peak-to-average power ratio. Nonlinear impairment of an RF-modulated continuous wave is characterized by the second- and third-order intermodulation distortion (IMD2 and IMD3). By contrast, an RF-modulated frequency comb is characterized by a distinct IMD2n and IMD3n for each comb line n. We study the effect of modulation depth on nonlinearity in frequency combs, comparing modulation depths of 4% and 8%. When we include bleaching, we ?nd that the OIP3n, third-order intercept point for the n-th comb line, increases when the modulation depth increases for comb lines at frequencies above 2 GHz (n (cid:2) 40), so that distortion decreases. We show that this effect occurs because bleaching attenuates lower frequencies more than higher frequencies and this preferential attenuation increases as the modulation depth increases.
关键词： MUTC,IMD2,IMD3,frequency comb,nonlinearity,bleaching
更新于2025-09-19 17:13:59
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Junction-less optical phase shifter loaded silicon Mach Zehnder modulator
摘要： In this paper, we design and numerically analyze the performance of electrostatic doping (ED) assisted junction-less optical phase shifter loaded silicon Mach-Zehnder (MZM), which is realizable on the 220 nm SOI platform. The proposed phase shifter contains a vertical metal–insulator–semiconductor (MIS) junction and a lateral metal-semiconductor (MS) junction. Change in the refractive index profile inside the rib waveguide, which supports the phase shifter, is achieved by altering the concentration of free carriers via the plasma dispersion effect. Numerical simulation using commercially available TCAD tool and mode solver are used to estimate the performance of the proposed modulator. Two different sets of materials are used as electrodes to realize the MIS-MS charge plasma diode. In one design gold (Au) and silver (Ag) is used as electrode material while the other design utilizes palladium (Pd) and aluminum (Al) as electrode material. The performance of the proposed modulator(s) is extensively studied both in steady state and transient state. A complete analysis of chirp and nonlinear distortion for the proposed modulator are also presented in the paper. Results predict that a maximum of 15.4 dB dynamic extinction ratio (ER) is achievable with a minimum of 3.2 dB insertion loss (IL). The proposed modulator is expected to provide a maximum of 30.3 Gbps operating speed with 22.2 GHz of 3-dB electro-optical bandwidth. Simulation result predicts that the worst case dynamic energy per bit for the proposed ED assisted MZM is approximately 54.4 fJ/bit.
关键词： work-function,intensity modulator,IMD3,electrostatic doping,plasma dispersion effect,Mach-Zehnder modulator
更新于2025-09-04 15:30:14