A compact and highly selective triple band notch UWB (3.3 GHz -10.7 GHz) filter is presented. Low insertion loss UWB pass band characteristics is achieved by two coupled multi mode resonators (MMR ₁ and MMR ₂ ). Desired triple band notch characteristics and sharp UWB filter characteristics are achieved by introducing transmission zeroes (TZs). Three band notches are implemented to mitigate the potential interferer signals at 4.42 GHz (Radio altimeter ITU band), 5.54 GHz (WLAN) and 7.64 GHz (Satellite communications). Wide upper stop band is realized by incorporating a stepped impedance low pass filter structure. The filter is realized on a RT/Duroid 5880 substrate (ε _r = 2.2 and thickness = 0.8 mm) and measured to validate the predicted results. The group delay of the filter is relatively constant and less than 0.45 ns over the desired pass band.

We investigate and demonstrate the thermal crosstalk problem in integrated photonic circuits with metal and silicon doped heaters. Further, we illustrate that due to the localized heating effect, integrated doped heaters are out-performed in terms of thermal crosstalk as compared to integrated metal heaters. To mitigate thermal crosstalk and enhance phase tuning efficiency further, a CMOS compatible air-filled trench region is realized between the doped heater and the adjacent element. The performances of three fundamental building blocks of integrated photonic circuits, namely, a PN phase shifter, an optical attenuator, and a ring resonator, are tested by full-wave thermal, charge, and optical simulations. Additionally, the impact of thermal crosstalk on the performance of integrated PN phase shifters and optical attenuators is examined thoroughly. The proposed low crosstalk thermal phase shifters might be very beneficial for densely routed complex integrated photonic circuits like photonic transceivers for data centers, optical phased array antennas, and photonic reservoirs.

In this paper, a systematic synthesis approach is proposed for achieving negative group delay responses using lossy coupling matrix. It is mathematically proved that, for a passive and reciprocal network, loss is the necessary condition to realize a negative group delay. Also, the optimum strategy is to place zeros and poles of the transfer function on the left complex plane. A closed-form relation between the group delay and magnitude is then derived based on this strategy, and followed by a complete synthesis approach using coupling matrix. Two numerical and one experimental examples are finally given to illustrate the proposed synthesis method.

We report a thorough analysis of the thermal crosstalk issue for silicon photonic circuits using metal and doped silicon heaters for the two waveguide configurations, rib and strip waveguides. Full-wave thermal and optical simulations are performed and it is observed that integrated doped heaters with strip waveguides have the best thermal crosstalk performance. Also, the effect of metal contacts on the heater power consumption is investigated. Furthermore, to alleviate the phase crosstalk and improve the phase tuning efficiency, a deep trench is implemented to thermally shield an adjacent waveguide. Two well-known photonic components, namely, integrated Mach-Zehnder modulators and PN phase shifters are designed and the thermal crosstalk performance is analyzed rigorously. The proposed photonic phase shifter is outperformed in terms of thermal crosstalk over the existing designs. Such phase shifters are viable for compact silicon photonic circuits operating at a very high temperature.

Nowadays, robust sensors for glucose-sensing application are almost a necessity for every diabetic individual. In this work, a (20 mm $\times10$ mm) contact-based sensor has been successfully realized on a thin and flexible polyamide substrate, with the sensing area being a bifilar spiral resonator (BSR). The proposed sensor was based on detecting resonance frequencies shifts at ultrahigh frequencies (UHFs) as a result of changes in the glucose concentration. The BSR acts as a cascaded metasurface which, at around the resonant frequency, forms a plasmon dispersion at the interface between a glucose solution and the BSR. An empirical formula has been developed to express the sensing sensitivity as a function of the loss factor, the oscillator strengths and the steady state permittivity. The model has been experimentally validated with an in vitro measurement on an aqueous glucose solution and an ex-vivo measurement on a serum blood solution. The measured results suggest that there exists a positive and linear correlation between glucose concentration and the resonant frequency shift within the clinical diabetic range. The sensor sensitivity was 250 megahertz (MHz)/(mg/mL) for the aqueous glucose solution and 130 MHz/(mg/mL) for the serum blood along with a $Q$ -factor of 20. Overall, the measured results were highly consistent with our theoretical expectation. Moreover, the proposed sensor was highly resistant to bending losses.

This paper proposes Young’s double slit method based high gain broadband higher order mode spoof surface plasmon leaky wave antenna sensor (SSPLWA) for dual beam and sensing applications. Following and mimicking the double slit principle in microwave frequencies, the proposed surface plasmon leaky wave antenna sensor operating on higher order modes has been successfully measured to obtain a wideband of more than 15GHz (88.5%) and generate two simultaneous radiating beams towards the endfire direction with a peak gain of 16.6 dBi. The proposed antenna sensor operates in a broad frequency range from 10GHz-25GHz and maintains a minimum gain of > 10 dBi in the whole operating band. The SSPLWA has been tested by designing two prototypes without and with additional horizontal conducting strips so as to improve the overall gain, reflection and efficiency. The prototype with horizontal strips has been further tested for sensing application i.e. aqueous glucose solutions and it is found that the proposed dual beam sensor is providing high sensitivity and very stable measurement results in terms of resonance frequency shifts or magnitude variations. The proposed antenna sensor has achieved a high peak efficiency of 95 percent and can be very useful for dual beam applications and wireless sensing measurements.