Use of Reconfigurable IM Regions to Suppress Propagation and Polarization Dependent Losses in a MMI Switch

With this work, use of reconfigurable index modulated (IM) regions to accelerate the performance of a multimode interference (MMI) based photonic switch is presented. Appropriate dimension for such regions are defined to suppress the transition losses and to optimize the area coverage. It has been noticed that by reconfiguring the IM regions, perfect switching for test wavelengths of 1.3μ m and 1.55μ m with low insertion loss (I.L.) levels, ≤ 1.2dB and excess loss (E.L.) levels, ≤ 0.17dB can be achieved with vacillation of extremely low polarization dependent losses (PDLs), which are ≤ 0.15dB. For either case of input test wavelengths, generated crosstalk (CT) levels are found better than -21.8dB for TE and -20.2dB for TM polarization state

Substrate Current Evaluation for Lightly and Heavily Doped MOSFETs at 45 Nm Process Using Physical Models

Substrate noise is a major integration issue in mixed signal circuits; particularly at radio frequency (RF) it becomes a key issue. In deep sub micron MOSFETs hot carrier effect induces device degradation. The impact ionization phenomenon is one of the main hot carrier effects. The paper covers the process and device level simulation of MOSFETs by TCAD and the substrate current comparison in lightly and heavily doped MOS. PMOS and NMOS devices are virtually fabricated with the help of ATHENA process simulator. The modeled devices include the hot carrier effects. The MOS devices are implemented on lightly and heavily doped substrates and substrate current is evaluated and compared with the help of ATLAS device simulator. Substrate current is better in lightly doped substrate than in heavily doped one. Drain current is also better in lightly doped than heavily doped substrates. Silvaco TCAD Tool is used for Virtual fabrication and simulation. ATHENA process simulator is used for virtual fabrication and ATLAS device simulator is used for device characterization

Substrate Current Evaluation for Lightly and Heavily Doped MOSFETs at 45 nm process Using Physical Models

Substrate noise is a major integration issue in mixed signal circuits; particularly at radio frequency (RF) it becomes a key issue. In deep sub micron MOSFETs hot carrier effect induces device degradation. The impact ionization phenomenon is one of the main hot carrier effects. The paper covers the process and device level simulation of MOSFETs by TCAD and the substrate current comparison in lightly and heavily doped MOS. PMOS and NMOS devices are virtually fabricated with the help of ATHENA process simulator. The modeled devices include the hot carrier effects. The MOS devices are implemented on lightly and heavily doped substrates and substrate current is evaluated and compared with the help of ATLAS device simulator. Substrate current is better in lightly doped substrate than in heavily doped one. Drain current is also better in lightly doped than heavily doped substrates. Silvaco TCAD Tool is used for Virtual fabrication and simulation. ATHENA process simulator is used for virtual fabrication and ATLAS device simulator is used for device characterization

Fabrication of graphene-ZnO heterostructure-based flexible and thin platform-based UV detector

This work presents the performance evaluation of Graphene/ZnO Schottky junctions grown on flexible indium tin oxide (ITO)-coated polyethylene terephthalate (PET) substrates. The fabricated structures include chemical vapour deposition grown graphene layer on ITO-coated PET substrates. Polymethyl methacrylate assisted transfer method has been employed for the successful transfer of graphene from Cu substrate to PET. The smaller D-band intensity (1350 cm−1) compared to G-band (1580 cm−1) indicates good quality of carbon lattice with less number of defects. High-quality ZnO has been deposited through RF sputtering. The deposited ZnO with grain size 50–95 nm exhibited dislocation densities of 1.31270 × 10–3 nm−2 and compressive nature with negative strain of − 1.43156 GPa. Further, the electrical and optical characterization of the devices has been done through device I–V characterization and UV detection analysis. The UV detection capability of the device has been carried out with the aid of a UV-lamp of 365 nm wavelength. The fabricated graphene/ZnO photodetector showed good response to UV illumination. The device performance analysis has been done through a comparison of the device responsivity and detectivity with the existing detectors. The detectivity and responsivity of the fabricated detectors were 7.106 × 109 mHz1/2 W−1 and 0.49 A W−1, respectively

Ultrabroad supercontinuum generation in tellurite equiangular spiral photonic crystal fiber

Simulations are presented of a very broad and flat supercontinuum (SC) in both the normal and anomalous group velocity dispersion regimes of the same equiangular spiral photonic crystal fiber at low pumping powers. For a pump wavelength at 1557 nm and average pump power of 11.2 mW, we obtained a bandwidth >3 μm (970 nm–4100 nm) at 40 dB below the peak spectral power with fiber dispersion 2.1 ps/km nm at 1557 nm. In the same fiber, at pump wavelength 1930 nm and average pump power of 12 mW the SC bandwidth was more than two octaves (1300 nm–3700 nm) and dispersion was 1.3 ps/km nm at 1930 nm. This demonstrates the potential use of the fiber for multi-wavelength pumping with commercially available sources at fairly low power

A versatile all-optical parity-time signal processing device using a Bragg grating induced using positive and negative Kerr-nonlinearity

The properties of gratings with Kerr nonlinearity and PT symmetry are investigated in this paper. The impact of the gain and loss saturation on the response of the grating is analysed for different input intensities and gain/loss parameters. Potential applications of these gratings as switches, logic gates and amplifiers are also shown

Recent development and futuristic applications of MEMS based piezoelectric microphones

This paper presents a comprehensive literature survey of MEMS based piezoelectric microphones along with the fabrication processes involved, application domains, and methodologies used for experimentations. Advantages and limitations of existing microphones are presented with the impact of process parameters during the thin film growth. This review identifies the issues faced by the microphone technologies spanning from the invention of microphones to the most recent state-of-the-art solutions implemented to overcome or address them. A detailed comparison of performance in terms of sensitivity and dynamic range is presented here that can be used to decide the piezoelectric material and process to be used to develop sensors based on the bandwidth requirement. Electrical and mechanical properties of different piezoelectric materials such as AlN, ZnO, quartz, PZT, PVDF, and other polymers that has great potential to be used as the sensing membrane in development and deployment of these microphones are presented along with the complications faced during the fabrication. Insights on the future of these sensors and emerging application domains are also discussed

Impact of dispersive and saturable gain/loss on bistability of nonlinear parity-time Bragg gratings

We report on the impact of realistic gain and loss models on the bistable operation of nonlinear parity–time (PT) Bragg gratings. In our model we include both dispersive and saturable gain and show that levels of gain/loss saturation can have a significant impact on the bistable operation of a nonlinear PT Bragg grating based on GaAs material. The hysteresis of the nonlinear PT Bragg grating is analyzed for different levels of gain and loss and different saturation levels. We show that high saturation levels can improve the nonlinear operation by reducing the intensity at which the bistability occurs. However, when the saturation intensity is low, saturation inhibits the PT characteristics of the grating

Ultrafast optical switching using parity-time symmetric Bragg gratings

This paper reports on time-domain modeling of an optical switch based on the parity–time (PT) symmetric Bragg grating. The switching response is triggered by suddenly switching on the gain in the Bragg grating to create a PT-symmetric Bragg grating. Transient and dynamic behaviors of the PT Bragg gratings are analyzed using the time-domain numerical transmission line modeling method including a simple gain saturation model. The on/off ratio and the switching time of the PT Bragg grating optical switch are analyzed in terms of the level of gain introduced in the system and the operating frequency. The paper also discusses the effect the gain saturation has on the operation of the PT-symmetric Bragg gratings

Optimization and fabrication of MEMS based piezoelectric acoustic sensor for wide frequency range and high SPL acoustic application

This paper reports finite element model (FEM) simulation and fabrication of a square shaped diaphragm along with microtunnel for MEMS acoustic sensor which can be used for measurement of wide operational frequency range and high sound pressure level (SPL) 100 dB–180 dB measurement in launching vehicle and aircraft. The structure consists of a piezoelectric ZnO layer sandwiched between two aluminum electrodes on a thin silicon diaphragm. There is a microtunnel in the structure which relates the cavity to the atmosphere for pressure compensation. The microtunnel decides the lower cut-off frequency of device. Analytical and simulation approaches are used to optimize microtunnel dimension and simulation approach for diaphragm structure optimization. The change in displacement, stress, sensitivity and resonance frequency due to different diaphragm sizes with diaphragm thickness variation is also analyzed. The optimized diaphragm structure of 1750 × 1750 μm2 and microtunnel of 100 μm wide and 24 μm deep have been fabricated using bulk micromachining technique. The fabricated device response has been tested using LDV and sensitivity measurement system