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In this paper, we present refractive index measurement using a double-slot silicon waveguide-based Mach Zehnder interferometer. We present a double-slot waveguide that offers the best sensitivity and limit of detection compared to wire and single-slot waveguides. We demonstrate ultra-low loss coupling between a single-mode waveguide and a double-slot waveguide and experimental proof for double-slot excitation. The double-slot waveguide is used to demonstrate a highly sensitive concentration sensor. An unbalanced Mach-Zehnder is used as the sensor device to demonstrate concentrations of Potassium Chloride in deionized water. A sensitivity of 700 nm/RIU and a limit of detection (LOD) of 7.142e^-6 RIU are achieved experimentally. To the best of our knowledge, the demonstrated sensitivity is the highest for an on-chip guided waveguide sensing scheme., Comment: 6 pages,10 figures

Thin film silicon nitride (75 nm$ of 3dB bandwidth. We present a detailed design strategy, simulation, fabrication and characterization data on the effect of various parameters on the coupling.

Thin-film ferroelectric oxide materials over the year have been explored for various electronic applications. Recently, the electro-optic properties of these materials have gained considerable interest as an integrated high-speed electro-optic modulator. Particularly, bulk Barium Titanate has the highest electro-optic response. However, the effect of thin film, domain orientation, and polling on the electro-optic response is not well understood. In this article, we present the domain effects of thin-film ferroelectric Barium Titanate on the electro-optic response in a waveguide configuration. We also show the impact of drive electrode orientation with respect to the in-plane polarisation angle in a multi-domain structure.

We demonstrate a miniaturized wafer-scale optical gas sensor that combines the gas cell, an optical filter, and integrated flow channels. We present the design, fabrication and characterization of an integrated cavity-enhanced sensor. Using the module, we demonstrate absorption sensing of ethylene down to 100 ppm level.

In filter based reactive power measurements, the voltage is phase shifted by $$90^\circ$$ relative to the current. This paper presents a technique of measuring reactive power based on differential $$90^\circ$$ shifter. According to this method, the sampled voltage and the current signal passes through a pair of FIR filters that shifts $$+\,45^\circ$$ and $$-\,45^\circ$$ . Then, the two outputs are multiplied to measure the reactive power. A pair of FIR filters that are having identical flat magnitude responses and orthogonal phase responses are designed. Multiplier-less FIR structure is adopted for hardware implementation to reduce the chip area cost making the technique implementable in digital power meter. A detailed hardware architecture and its implementation in FPGA is presented. Furthermore, the measurement of reactive power for various frequencies between 50 and 250 Hz is also presented.

The integration of BaTiO3 with Si(100) is essential to exploit its ferroelectric capabilities in the well-established Si-complementary metal–oxide–semiconductor (CMOS) technological platform. To en...

This paper presents design, mathematical analysis, and measurement of low noise single-stage transimpedance amplifier (TIA) with scalable bandwidth using 130 nm bipolar complementary metal-oxide-semiconductor (BiCMOS) silicon-germanium (SiGe) process. Common-emitter (CE) shunt-shunt feedback topology with active inductor peaking has been used in the design for improving noise, gain and driving capability of TIA by decreasing the input and output impedance, respectively. The use of active inductive peaking in CE shunt-shunt feedback topology has resulted in a new TIA configuration with better performance. The circuit has been optimized for low noise by adopting the proposed design technique. Validity of the mathematical analysis and design for the proposed TIA has been established with the help of simulations as well as measurement results. The measurement results of Ku-band TIA (10 MHz to 14 GHz) have demonstrated a transimpedance gain of $53.2~dB\Omega $ , input-referred current noise of 16.8 pA/ $\sqrt {Hz}$ with power consumption of $9.8~~mW $ . The design architecture is adaptable for higher frequency bands, which has been demonstrated by designing another TIA covering K- and Ka-bands (10 MHz to 35 GHz) with transimpedance gain of 33.4 dB $\Omega $ , input-referred current noise of 29.4 pA/ $\sqrt {Hz}$ with power consumption of $28.1~~mW $ in the post-layout simulation results, and occupies same chip area as that of 14 GHz, i.e., $0.1\times 0.21\,\,mm^{2}$

The interaction of light with collective charge oscillations, called plasmon-polariton, and with polar lattice vibrations, called phonon-polariton, are essential for confining light at deep subwavelength dimensions and achieving strong resonances. Traditionally, doped-semiconductors and conducting metal oxides (CMO) are used to achieve plasmon-polaritons in the near-to-mid infrared (IR), while polar dielectrics are utilized for realizing phonon-polaritons in the long-wavelength IR (LWIR) spectral regions. However, demonstrating low-loss plasmon- and phonon-polaritons in one host material will make it attractive for practical applications. Here, we demonstrate high-quality tunable short-wavelength IR (SWIR) plasmon-polariton and LWIR phonon-polariton in complementary metal-oxide-semiconductor compatible group III-V polar semiconducting scandium nitride (ScN) thin films. We achieve both resonances by utilizing

In this letter, we present a photonics integrated piezoMEMS (PipMEMS) platform for next-generation MEMS. We demonstrate on-chip optical transduction of a piezoMEMS structure. We use a heterogeneous 3D-bonding approach to integrate silicon photonics interrogator chip and lead–zirconate–titanate (PZT)-based MEMS device. We report on-chip measurements of three resonance modes of the PiezoMEMS beam that shows an excellent agreement with conventional laser Doppler vibrometer measurement. We also demonstrate measurement in a vacuum with one order of magnitude improvement in the quality factor of the fundamental resonance mode.

We demonstrate static and dynamic bulk refractive index measurement using slot-waveguide based ring resonator. A detailed simulation is performed to optimize the slot-waveguide geometry for maximum sensitivity. The on-chip measurements are performed using a slot waveguide ring resonator by applying aqueous solutions of acids and bases at different concentrations. Based on these measurements, we derive a relation of refractive index change per unit change in concentration of the liquids in water. We experimentally measured a maximum sensitivity of 476 nm/RIU, enabling a limit of detection ( LOD ) of ${1.05}\times {10}^{-{5}}$ RIU. Finally, we demonstrate dynamic refractive index on-chip measurement by diluting potassium bicarbonate with hydrogen peroxide.

This work presents a wafer-scale two-step liquid phase crystallization process to obtain polycrystalline but epitaxial germanium on 2”-silicon wafers (Ge-on-Si). The crystallinity is confirmed using Raman spectroscopy and X-ray diffraction, with an extracted dislocation density of 108cm−2, an improvement of 10x over the previous report. The scanning electron imaging shows a uniform Ge film with a grain size of up to $12~\mu \text{m}$ . Metal-semiconductor-metal (MSM) near-infrared (IR) photodiodes are fabricated on the epitaxial Ge with two different electrodes and two different surface passivation interlayers. Irrespective of the electrode/passivation combination, all devices exhibit Ohmic characteristics. Contact resistivity varies from 3 $\text{m}\Omega $ cm2 to 560 $\text{m}\Omega $ cm2. This is contrary to virtually every previous report on MSM detector on n -type Ge . To probe further, kelvin probe force microscopy is used to characterize the surface potentials at grain boundaries and metal- Ge interfaces. The grain-to-grain band bending is very low, ~40 meV, hence, device characteristics are completely dominated by the metal- Ge band-bending which is 150–300 meV. The MSM devices using amorphous-Ge(30nm)/ Al (100nm) and TiO2 (5nm)/ Au (80nm) electrodes show an average spectral responsivity (SR) of 0.50 ± 0.16 A/W and 0.35 ± 0.09 A/W at 1550 nm and voltage bias of -3V, respectively. The maximum SR is 0.78 A/W and 0.48 A/W, respectively.

We present an on-chip photodetector integrated wavelength filter on a SiN-on-silicon-on-insulator (SOI) platform in the 850 nm wavelength window. The wavelength filter is designed using an echelle grating with a distributed Bragg reflector as the grating reflectors. We present the design and experimental realization of a six-channel wavelength filter with a channel spacing of 10 nm. Experimentally, we achieve an insertion loss of 4.3 dB and an adjacent channel cross talk of 22 dB. We demonstrate a silicon nano-slab waveguide integrated metal–semiconductor–metal photodetector with a maximum responsivity of 0.56 A/W and dark current of 217 nA. Furthermore, we demonstrate the integration of the echelle grating with the detector and show the feasibility of a CMOS compatible SiN-on-SOI platform for various applications, including short-reach communication and sensing applications.

We demonstrate polarization-independent grating couplers, single-mode waveguide and ring resonator for the first time in the GaN-on-Sapphire waveguide platform. We present material characterization, device simulation and experimental results.

On-chip electro-optic modulation is essential to realize complex on-chip optical signal processing. Recent developments in thin-film ferroelectric oxide for high-speed electro-optical modulators have gained considerable interest in understanding and correlating the material property with the electro-optic response. Particularly, the effect of thin film, domain orientation, and polling on the electro-optic response is not well understood. In this article, we present the effect of ferroelectric domains of thin-film Barium Titanate on the electro-optic response in a waveguide configuration. We also show the impact of drive electrode orientation with respect to the in-plane polarization angle in a multi-domain structure. Our theoretical findings corroborate the experimental observations in the literature, which substantiate the theoretical framework.

We present for the first time sputter deposition of PZT -on-SOl for electro-optic modulation. We present material, electric and electro-optic characteristics of a thin-film PZT -on-silicon. We demonstrate DC electro-optic characteristics using a ring resonator with a shift of 12.5 pm/V.

We demonstrate controlled phase tuning of thermal evaporated germanium antimony telluride (GST) integrated silicon ring resonator. The controlled cycling allows access to multi-states resulting in multi-photonic states for the potential neuromorphic application. We present and correlate electrical and photonic phase transition of ring integrated GST.

This paper presents the design and demonstration of a 35 GHz transmitter for RF-over-fiber (RFoF) communication link using complementary metal-oxide-semiconductor (CMOS) compatible silicon-photonics technology. This proof of the concept has addressed the high-frequency integration challenges and been realized using a fabricated broadband silicon-photonics microring modulator, driver amplifier, and were integrated on Kovar substrate using 50 Ω transmission line. The integrated test set-up has demonstrated the measured electro-optical (S 21 ) bandwidth of 35 GHz, maximum gain of 12.4 dB, RF matching at driver amplifier input in the range of −5 dB to −42 dB and optical matching at microring modulator input in the range of −8 dB to −21 dB for 50 Ω load across 35 GHz frequency bandwidth.

We design and experimentally demonstrate highly efficient Silicon Nitride based grating couplers with bottom distributed Bragg reflectors. All the layers were deposited using plasma enhanced chemical vapor deposition processing. We present gratings on two Silicon Nitride thickness (400 nm and 500 nm) platforms. On a 500 nm thick Silicon Nitride, we show a peak coupling efficiency of -2.29 dB/coupler at a wavelength of 1573 nm with a 1 dB bandwidth of 49 nm. On a 400 nm thick platform, we demonstrate a coupling efficiency of -2.58 dB/coupler at 1576 nm with a 1 dB bandwidth of 52 nm. The demonstrated coupling efficiency is the best reported as yet, for both 400 nm and 500 nm thick, plasma deposited Silicon Nitride platforms.

We demonstrate transparent in-contact electrical interconnects over SiN micro-ring resonators using metallic carbon nano-tubes (CNTs). Self-assembled stripes of metallic CNTs are directly in contact with the waveguide operating around 1550 nm wavelength. The absorption by the CNTs around 1550 nm is negligible for a coverage of about 2 % of the micro-ring. The optical performance of the resonator is unaffected till a current density of 35 μ A ∕ μ m . Semi-conducting CNTs with a similar coverage also have negligible absorption around 1550 nm . These metallic and semi-conducting CNTs hold promise for the implementation of transparent electronic circuits over SiN-photonic platform.

This paper presents the design and implementation of a 7-bit S-band digital passive phase shifter using Complementary Metal-Oxide-Semiconductor (CMOS) 65-nm technology in 2.6- to 3.2-GHz frequency band. New switched delay network topology has been used for 5.625 degrees and 2.8 degrees, and modified switched filter topology has been used for implementation of other phase bits to achieve 7-bit performance with low insertion loss and better isolation. The measured results of the fabricated chip show 7-bit performance with an average insertion loss of 11 dB, average root mean square (RMS) phase error of less than 2.0 degrees, average RMS amplitude error of less than 0.6 dB, input matching (S-11) better than -7.5 dB, and output matching (S-22) better than -14.5 dB across the target frequency band at 50 omega input/output impedance.

We demonstrate an on-chip in-plane polarization independent multi-spectral color filter in the visible to near-infrared wavelength band. We experimentally show a four-channel transmission and in-plane spectral filter characteristics spanning a 400-nm spectral range. Engineered 2D guided mode resonance structures in a silicon nitride-on-sapphire substrate are used to realize the filters. The in-plane color filters could provide the necessary impetus for developing robust integrated photonic platforms for on-chip devices and applications.

We experimentally demonstrate the Fano resonance in a corrugated ring coupled to a corrugated bus waveguide system and report that it is strongly dependent upon the coupling gap between ring and waveguide.

Thermo-optic effect is the simplest and most cost-effective method for reconfiguring an optical cavity, but fails to tune the optical loss in an ordinary cavity. By embedding an interferometer within an optical cavity, we demonstrate thermo-optic tuning of the quality factor from 3000 to 10000 and extinction ratio from ~0 dB to 25 dB in a completely passive silicon micro-ring resonator. This is an important step towards realizing cost-effective reconfigurable photonic devices in purely passive waveguide platforms.

We demonstrate 1X6 SiN echelle grating filters integrated with silicon nano-slab metal-semiconductor-metal photodetector for SWDM based short-reach interconnect. Echelle grating measures 4.3 dB insertion loss and 22 dB crosstalk. Photodetector records 0.59 A/W responsivity.

In this paper, we demonstrate controlled phase tuning of thermally evaporated germanium antimony telluride (GST) integrated silicon ring-resonator for potential neuromorphic application. We present and correlate electrical and photonic phase transition of ring integrated GST.

We demonstrate high-efficiency Silicon Nitride gratings for fiber-chip coupling in 850-900 nm. Experimentally measured peak efficiency is -4.44 dB and -3.4 dB for uniform and apodized gratings, respectively.

We report continuous electrolyte concentration measurement along a flow-channel using ring-loaded Mach-Zehnder interferometer in SOI platform. We also present the effect of hydrogen peroxide on the electrolyte concentration. The measured concentration shows excellent agreement with the Abbe refractometer.

We present a compact on-chip resonator enhanced silicon metal-semiconductor-metal (MSM) photodetector in 850 nm wavelength band for communication and lab-on-chip bio-sensing applications. We report the highest responsivity of 0.81 A/W for a 5 µm long device. High responsivity is achieved by integrating the detector in a silicon nitride ring resonator. The resonance offers 100X responsivity improvement over a single-pass photodetector due to cavity enhancement. We also present a detailed study of the high-speed response of the cavity and single-pass detector. We report an electro-optic bandwidth of 7.5 GHz measured using a femtosecond optical excitation. To the best of our knowledge, we report for the first time silicon nitride resonator integrated Si-MSM detector in SiN-SOI platform.

In this paper, we present the first demonstration of a promising technology that enables integration of a PiezoMEMS device and on-chip optical read-out. We demonstrate sensor integration by bonding a PZT-based microbeam on a silicon photonics-based resonance interrogator. We report on-chip measurement of three resonance modes of PiezoMEMS beam. We find excellent agreement between on-chip photonics and conventional LDV measurement. We also demonstrate measurement in a vacuum with one-order improvement in the quality factor of the fundamental resonance mode

High repetition rate pulsed lasers are used for applications such as highspeed optical communications, nonlinear optics and optical sampling. Conventionally, mode locked lasers are used as pulsed sources. However, they suffer from low repetition rate that is not tunable. Electro-optic modulation allows generation of frequency combs with tunable high repetition rate. These combs can be compressed to generate pulses, but the pulse widths are large owing to the limited bandwidth of electro-optic frequency combs. Though, modulators can be cascaded to scale the bandwidth, it is only a linear enhancement and requires additional RF components. Spectral broadening of these combs in nonlinear fibers results in marginally improved bandwidths. The broadening achieved at a given optical power can be enhanced several times by suitably modifying the temporal profile of the comb before spectral broadening with a pulse-shaper. In this work, electro-optic intensity and phase modulators are driven at 25GHz to generate an initial comb. A pulse-shaper adaptively optimises the temporal profile of the electro-optic frequency comb to enhance the spectral broadening in highly nonlinear fiber (HNLF). The optimised comb is power scaled in an Er-Yb co-doped fiber amplifier before HNLF. The adaptively optimised comb is compressed with single mode fiber and is characterized with zero delay implementation of spectral shearing interferometry to obtain the spectral phase and temporal profile of the pulses. The output pulses have 1 dB bandwidth of ~0.6 ps and 3 dB bandwidth of ~ 1 ps with high repetition rate of 25GHz. This adaptive technique is shown to be immune to drifts and changes in modulator drive conditions.

On-chip spectroscopy in visible and near-infrared wavelength offers immense potential for various screening and diagnostic application. Silicon Nitride (SiN) is a promising material to realize on-chip spectroscopy as it is transparent over a broad wavelength spectrum; visible-to-mid-infrared. Besides, it is compatible with the CMOS process technology. Since SiN can be deposited using various deposition techniques, it is essential that an appropriate deposition process is chosen to achieve desired properties. We present a detailed study of SiN films deposited using PECVD and LPCVD process. The films were characterized for various, material and optical properties. We also performed waveguide transmission measurement on different SiN films and found a strong correlation with material properties such as stress and autofluorescence to achieve low-loss waveguide. Using the optimized material, we design, fabricate, and demonstrate single-mode SiN wire, spiral waveguides and grating fiber-chip coupler at visible (λ =520nm) and near infra-red (λ = 780nm) wavelengths used for spectroscopy. Furthermore, we use a waveguide to efficiently excite fluorescence or Raman active molecules drop casted as the top cladding of the waveguides. A fraction of the isotopically emitted fluorescence or Raman signal couples back to waveguide and rest is emitted normal to the surface. We discuss the theoretical efficiencies of both the methods of collection and compare it with the conventional microscope-based spectroscopic system. Waveguide based spectroscopic sensing offers higher efficiency due to increased light-matter interaction along the length of the waveguide. We presented detailed design, simulation, and experimental demonstration of grating coupler waveguide system suitable for son-chip spectroscopy application.

We experimentally demonstrated polarization independent, angle tolerant mid-infrared notch filters using amorphous-Germanium 2D high contrast gratings. Centered at 7.42 pm wavelength, the filter exhibits wide field-of-view notch filtering characteristics across 0 to 30o incidence angles.