In this paper, we propose a highly linear electrostatic doping (ED) assisted dual series Mach-Zehnder modulator (MZM) suitable for photonic integrated circuits (PICs). A complete simulation study on ...the performance of the proposed dual series MZM is incorporated in this paper. We have analytically formulated the steady-state and the nonlinear performance of the proposed modulator and the simulation results using commercial grade photonic circuit simulator are also incorporated in support of the analytical study. Simulation results show that the proposed modulator can offer <inline-formula><tex-math notation="LaTeX">\sim 16</tex-math></inline-formula> dB of static extinction ratio (ER) with 3.2 dB of insertion loss (IL). The modulator offers approximately 10.2 dB of dynamic ER at 10 Gb/s data rate. The effect on the transfer function of the dual-series MZM due to the imbalance in the driving RF signals is also discussed supported with simulation results. The nonlinear performance of the proposed modulator is also estimated using analytical method and dual-tone test method. Results indicate that the spurious free dynamic range (SFDR) of the proposed dual series MZM for second and third order intermodulation distortions (IMD2 and IMD3) are 96.11 dB.Hz<inline-formula><tex-math notation="LaTeX">^{1/2}</tex-math></inline-formula>, and 132.4 dB.Hz<inline-formula><tex-math notation="LaTeX">^{2/3}</tex-math></inline-formula>, respectively. Study of the transient performance also reveals that the 3-dB electro-optic bandwidths are 11.39 GHz and 8.32 GHz for single and dual-series ED-assisted MZM, respectively.
Fiber Bragg Gratings or FBGs have achieved significant attention towards sensing and communication applications due to their outstanding advantages. Due to its high sensitivity towards various design ...parameters, it is now widely used to measure different physical and chemical parameters in various industrial sectors, including harsh environment applications. This review presents a comparative study of different FBG-based temperature and strain sensors reported in recent years. The analytical formulation for such sensors is also presented in brief. Necessary numerical simulation results are incorporated. For FBG based temperature sensors, both low and high range are considered. Similarly, for FBG-based strain sensors, both uniform and non-uniform strain are considered and discussed in brief. Apart from the sensing applications, new variants of FBG like secondary gratings and Random Optical Grating by Ultraviolet or ultrafast laser Exposure (ROGUE) gratings are also discussed.
In this paper, a novel microring resonator (MRR)-assisted Mach-Zehnder interferometric (MZI) structure to operate as an electro-optic half adder utilizing the optical switching phenomenon of Si-MRR ...is proposed. The proposed device has two Si-MRRs with dual inputs, used in the tandem configuration in the lower and upper arms of an MZI structure. An externally controllable optical ‘π’ phase shifter is also incorporated in one of the arms of the MZI. The carrier-injected forward-biased PIN waveguide structure is incorporated into the ring resonator architecture to achieve the extinction ratio (ER) tunability. For the proposed electro-optic adder, −1.85 V and +2 V are considered as logic 0 and 1, respectively. One of the output terminals will emulate an optical AND gate providing the carry bit (CB), while the other output terminal will emulate an optical EX-OR gate offering the sum bit (SB). The proposed device was modeled and simulated using MATLAB. The simulation results estimate the simulated static ER of the SB and CB is 27.44 dB and 18.08 dB, respectively. To demonstrate the proposed device’s efficacy, two 10 Gb/s PRBS input streams at 1550 nm were used, and the time domain simulation results indicate a successful electro-optic half adder suitable for photonic integrated circuits (PICs).
In this paper, we proposed a novel electro-optic reconfigurable OR to Ex-OR gate and vice-versa. The proposed design consists of two microring resonators (MRR), employed in parallel, in a ...Mach–Zehnder interferometric (MZI) structure’s upper and lower arms with a tunable phase shifter attached in its lower arm, and can be controlled externally. The design will work as an OR gate when the phase of the tunable phase shifter is 0, and it will work as an Ex-OR gate when the phase is ‘π’. The micro-ring resonator employs an electro-optic modulation technique based on carrier injection, with electrical voltage sets 2 V and -1.85 V respectively for logic 1 and logic 0. We have also studied the performance of the Ex-OR gate when the phase shift deviates from the ideal required value. The extinction ratio obtained for Ex-OR operation is 17 dB and for OR operation it is 7.58 dB respectively. To demonstrate the circuit’s working operation at a data rate of 10 Gbps, @1550 nm time domain simulations were carried out with two electrical information bit streams fed into it.
In this paper, we have studied the nonlinear performance and modeled the junction-less microring modulator (JL-MRM) designed on the standard silicon-on-insulator (SOI) platform. The JL-MRM utilizes ...the electrostatic doping effect to achieve the free carrier plasma dispersion effect in a silicon waveguide. A compact voltage-dependent steady-state model is analytically derived for JL-MRM. Using the compact steady-state model, closed-form expressions for the on–off extinction ratio (ER), optical modulation amplitude (OMA), and the quality of resonance (Q-factor) are also presented. We have also analyzed the nonlinear and chirp performance of JL-MRM. A small signal model for the MRM is also analyzed. The proposed device is simulated using commercially available TCAD and mode solver tools. Simulation results show that for a JL-MRM with 8.75 μm radius, the on–off ER and insertion loss (IL) are 20.5 dB and 1.98 dB, respectively. The estimated Q-value for MRM is approximately 11,630. From the proposed small signal model, the estimated 3-dB bandwidth, chirp parameter, and Q-value are found to be 28.29 GHz, -0.19, and 9979, respectively. From the nonlinear analysis, we also found that the proposed MRM for the input power level of 0 dBm offers approximately 82.15 dB.Hz1/2 and 109.87 dB.Hz2/3 of spurious free dynamic range (SFDR) for second harmonic and third harmonic distortions, respectively.
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 a 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 the electrode materials, while the other design utilizes palladium (Pd) and aluminum (Al) as the electrode materials. The performance of the proposed modulator(s) is extensively studied both in the steady state and transient state. A complete analysis of the 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.
In this paper, we propose and numerically analyze electrostatic doping (ED) assisted silicon microring modulator (MRM) realizable on SOI platform having ∼10nm free spectral range (FSR). The proposed ...modulator consists of a vertical metal–insulator–semiconductor (MIS) junction and a lateral metal–semiconductor (MS) junction. It utilizes ED to achieve free carriers inside the rib waveguide that eventually introduces the free carrier plasma dispersion effect. The proposed device does not employ any lateral or vertical PN or PIN junction and offers high operating speed with negligible static power consumption. Numerical simulation using commercially available TCAD tools and mode solvers are used to estimate the performance of the proposed modulators. Palladium (Pd) and aluminum (Al) are used as electrodes to realize ED enabled MIS–MS charge plasma diode. The performance of the proposed modulator is extensively studied both in steady state and transient state. Results predict that a maximum 37.8 dB and 33 dB of extinction ratio (ER) is achievable by the modulator while operating in inversion and accumulation mode, respectively. Predicted insertion losses are 1.97 dB and 1.49 dB when operated in inversion and accumulation mode respectively. The proposed modulator is expected to provide a maximum of 26.3 Gbps and 32.2 Gbps operating speed with a 9.21 GHz and 11.29 GHz of 3-dB optical bandwidth in inversion and accumulation mode of operation, respectively. Simulation result predicts that the dynamic energy per bit for the proposed ED assisted MRM is approximately 31 fJ/bit and 68 fJ/bit in inversion and accumulation mode of operation, respectively.
In this paper, we propose and analyze an electronically controllable 2 × 2 multimode interference (MMI) coupler-based photonic switch (PS) in form of a lateral p-i-n diode, which is realized on the ...silicon-on-insulator platform. The switching has been achieved by applying external bias voltage, which induces free carrier dispersion effect-based refractive index change. Theoretical analysis of the proposed PS based on perturbation theory is presented, and the results are verified by numerical simulations and full vectorial analysis. Analysis and simulation show that the proposed multimode interference photonic switch (MMIPS) can offer maximum 22.7 dB extinction ratio (ER) and '1.5 dB of maximum excess loss (EL). The maximum switching voltage is found to be '2.25 V. Optimization in terms of device length, doping concentrations, width of the intrinsic region, and position of the access waveguides for achieving desired values of ER and EL has been presented. Analysis also indicates strong polarization dependence of the proposed switch. Steady-state analysis of the proposed MMIPS confirms its operation over entire C-band (1530-1565 nm) with maximum 0.25 and 0.35 dB optical power variation in bar and cross port, respectively. It is found that the MMIPS can easily withstand a temperature variation of 20 K. Moreover, we show that change in switching performance due to temperature variation can also be compensated by adjusting external bias voltage. This paper also investigates the fabrication tolerances of MMIPS in terms of imperfections in device length, width, and doping concentrations. Study shows that ±100 nm variation in device length and ±50 nm variation in device width introduce maximum optical power variations of 0.3 and 0.1 dB in cross port (and 0.2 and 0.07 dB in bar port), respectively. The doping concentration variation, as permissible in state-of-the-art fabrication process, is found to introduce negligible penalty on the switching performance. Transient analysis and equivalent circuit model of the proposed switch confirms more than 1 GHz of switching speed. Small-signal equivalent circuit of the proposed MMIPS predicts power dissipation in the orders of tens of milliwatts.
In this paper, we propose and analyze the performance of a high-speed racetrack resonator (RTR)-based intensity modulator, which uses coupling coefficient modulation. The proposed modulator is ...realizable on the standard 220-nm silicon-on-insulator platform. The intensity modulation is achieved by modulating the coupling coefficient between the RTR and the access waveguide using a lateral p-i-n-diode-based active multimode interference (MMI) coupler. The coupling coefficient modulation has been achieved by creating a small perturbation in the refractive index profile inside the active MMI coupler. Theoretical analysis of the proposed modulator using the first-order perturbation theory and time-dependent dynamic model is presented. Analysis and simulation showed that the proposed modulator offers minimum 15.1 dB of static extinction ratio (ER) and ~5.4 dB of dynamic ER at 32 Gb/s data rate. It has been shown that the modulator can be designed for both 0.8 and 1.6 nm free spectral range and the required driving voltage is ~1.3 V. Both transient analysis and the small-signal model of the proposed modulator verify the maximum operating speed up to 32 Gb/s. Also, our analysis predicts that the power dissipation for the proposed modulator at 32 Gb/s is approximately 2.97 mW and thus, the energy dissipation per bit is ~86 fJ.
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