Negligible Insertion Loss Research Articles

Nonreciprocal Photon Transport in a Chiral Optomechanical System

AbstractChiral interaction between light and quantum emitters leads to emergence development of chiral quantum optics and stimulates a wide range of practical applications in quantum regime, such as single‐photon isolation and photon unidirectional emission. Cavity optomechanics studying the interaction between optical and mechanical resonators plays an important role in the field of quantum optics. However, how to achieve the chiral interaction between light and mechanical oscillators and explore the applications of the chiral optomechanical systems are still difficult encountered in cavity optomechanics. Here, a method is proposed to achieve chiral optomechanical interaction by exploiting directional squeezed light in a multimode optomechanical system. Based on the chiral interaction between photon and phonon, the nonreciprocal photon transport at a single‐photon level can be realized. An isolation ratio of and a negligible insertion loss for the photonic isolator are obtained. This method paves the way to realize chiral optomechanical interaction for conducting chiral optomechanics and opens up the prospect of exploring and utilizing chiral photon–phonon manipulation in the quantum regime.

Compact and Broadband Adiabatically Bent Superlattice-Waveguides With Negligible Insertion Loss and Ultra-Low Crosstalk

Broadband and ultra-low crosstalk integrated silicon superlattice waveguides are proposed and demonstrated, enabling high-density waveguide integration. The superlattice waveguides are implemented as S-shaped adiabatic bends that yield ultra-low crosstalks in the neighboring channels, and an extremely low insertion loss, for the TE polarization. Special materials or complex fabrication steps are not required. The bent superlattice waveguides are measured to have an average insertion loss <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\leq 0.1 \rm{dB}$</tex-math></inline-formula> for all channels. The average crosstalk values are <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\leq -37.8 \rm{dB}$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\leq -45.2 \rm{dB}$</tex-math></inline-formula> , in the first nearest neighboring waveguide and the second nearest neighboring waveguide, respectively. The transmission spectra are measured over the wavelength ranges of ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1.24 \mu \rm{m}$</tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1.38 \mu \rm{m}$</tex-math></inline-formula> ) and ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1.45 \mu \rm{m}$</tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1.65 \mu \rm{m}$</tex-math></inline-formula> ), covering both communication wavelengths of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1310$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1550\, \rm{nm}$</tex-math></inline-formula> . The simulation results predict an efficient broadband performance over the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$500\, \rm{nm}$</tex-math></inline-formula> wavelength range ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1200\, \rm{nm}$</tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1700\, \rm{nm}$</tex-math></inline-formula> ), covering all O, E, S, C, L & U bands. The proof of concept was done for a silicon-on-insulator platform and the approach is applicable to other waveguide geometries and integrated photonic platforms.

Generalized Concept and MATLAB Code for Modeling and Analyzing Wideband 90° Stub-Loaded Phase Shifters with Simulation and Experimental Verifications.

In the design of phase shifters, the modeling equations are too complicated and require some approximations to be derived correctly by hand. In response to this problem, this paper presents a generalized concept, algorithm, and MATLAB code that provide the exact modeling equations of the transmission parameters and the scattering parameters of any 90° wideband stub-loaded phase shifter. The proposed code gives the modeling equations in term of variables for any number of stubs and characteristic impedance value by utilizing the symbol-based analysis of the MATLAB code. It also illustrates the results as a function of normalized frequency relative to the center frequency fo, and can be and can be tailored to any user-defined frequency range. As a matter of comparison, a three-stub wideband 90° stub-loaded phase shifter is simulated using CST Microwave Studio and experimentally fabricated on Rogers RT5880 dielectric substrate with dimensions of 30 × 40 × 0.8 mm3. The comparison reveals the accuracy of the proposed computerized modeling with -10 dB impedance bandwidth equal to 90% (0.55fo-1.45fo), (90°∓5°) phase difference bandwidth equal to 100% (0.5fo-1.5fo), and negligible insertion loss. The novelty of this work is that the proposed code provides the exact modeling equations of the stub-loaded phase shifter for any number of stubs regardless the complexity of the mathematical derivations.

Artificial Gauge Field Enabled Low‐Crosstalk, Broadband, Half‐Wavelength Pitched Waveguide Arrays

AbstractDense waveguide arrays with half‐wavelength pitch, low‐crosstalk, broadband, and flexible routing capability are essential for integrated photonics. However, achieving such performance is challenging due to the relatively weaker confinement of dielectric waveguides and the increased interactions among densely packed waveguides. Here, leveraging the artificial gauge field mechanism, half‐wavelength‐pitched dense waveguide arrays, consisting of 64 waveguides, in silicon with −30 dB crosstalk suppression from 1480 to 1550 nm are demonstrated. The waveguide array features negligible insertion loss for 90° bending. This approach enables flexibly routing a large‐scale dense waveguide array that significantly reduces on‐chip estate, leading to a high‐density photonic integrated circuit, and may open up opportunities for important device performance improvement, such as half‐wavelength‐pitch optical phased array and ultra‐dense space‐division multiplexing.

High performance thin-film lithium niobate modulator on a silicon substrate using periodic capacitively loaded traveling-wave electrode

Thin-film lithium niobate (TFLN) based traveling-wave modulators maintain simultaneously excellent performances, including large modulation bandwidth, high extinction ratio, low optical loss, and high modulation efficiency. Nevertheless, there still exists a balance between the driving voltage and modulation bandwidth. Here, we demonstrate an ultra-large bandwidth electro-optic modulator without compromising the driving voltage based on the TFLN platform on a silicon substrate, using a periodic capacitively loaded traveling-wave electrode. In order to compensate the slow-wave effect, an undercut etching technique for the silicon substrate is introduced to decrease the microwave refractive index. Our demonstrated devices represent both low optical and low microwave losses, which leads to a negligible optical insertion loss of 0.2 dB and a large electro-optic bandwidth with a roll-off of 1.4 dB at 67 GHz for a 10 mm-long device. A low half-wave voltage of 2.2 V is also achieved. Data rates up to 112 Gb s−1 with PAM-4 modulation are demonstrated. The compatibility of the proposed modulator to silicon photonics facilitates its integration with matured silicon photonic components using, e.g., hybrid integration technologies.

Optimization of Scattering Parameters Through Numerical Investigation of One-Bit RF MEMS Switch Over Ku, K and Ka Band

Aim: Computation of loss factors for one-bit RF MEMS switch over Ku, K and Ka-band for two different insulating substrates. Objective: Numerical investigation of return loss, insertion loss, isolation loss are computed under both actuated and unactuated states for two different insulating substrates of the 1-bit RF MEMS switch, and corresponding up and down-capacitances are obtained. Methods: The unique characteristics of a 1-bit RF MEMS switch of providing higher return loss under both actuated and unactuated states and also of isolation loss with negligible insertion loss makes it as a prime candidate for phase shifter application. This is presented in this manuscript with a keen focus on improvement capability by changing transmission line width, and also of overlap area; where dielectric constant of the substrate also plays a vital role. Results: The present work exhibits very low down-capacitance over the spectrum whereas considerable amount of up-capacitance. Also when overall performance in terms of all loss parameters are considered, switch provides very low insertion loss, good return loss under actuated state and standard isolation loss. Conclusion: Reduction of transmission line width of about 33% improved the performance of the switch by increasing isolation loss. Isolation loss of -40 dB is obtained at actuated condition in higher microwave spectra for SiO2 at higher overlap area. Down capacitance of ~ 1dB is obtained which is novel as compared with other published literature. Moreover, a better combination of both return loss, isolation loss and insertion loss are reported in this present work compared with all other published data so far.

Ultrawideband, high-power, microstripline test setup for experimental study and characterization of multipactor.

This paper discusses different components of a high-power test setup for replicating multipactor in a laboratory environment. We developed a broadband test cell for parallel-plate multipactor discharges that can operate from DC to 1.2GHz. The proposed test cell design features a multi-step transition from a coaxial line to a microstripline with negligible insertion loss suitable for high-power breakdown experiments. The multipactor section is adjustable and replaceable, offering flexibility in conducting various multipactor tests, such as different gap distances and local surface treatments. We incorporated two local multipactor detection methods, an electron multiplier tube and a biased standalone probe to rapidly and reliably detect the growth of secondary electrons in the multipactor vicinity. The driving circuits of these detection methods have been designed to filter out RF coupling while preserving the detection signal due to multipactor current. To demonstrate the accuracy of the proposed test setup, we validated the multipactor thresholds determined in simulation using the 3D particle-in-cell module of CST Microwave Studio. We obtained very good agreement between simulation and experimental results over the broadband frequency range. The topics discussed in this paper further inform how to address the design obstacles encountered in developing a bench-top multipactor test setup.

Overlap junctions for superconducting quantum electronics and amplifiers

Due to their unique properties as lossless, nonlinear circuit elements, Josephson junctions lie at the heart of superconducting quantum information processing. Previously, we demonstrated a two-layer, submicrometer-scale overlap junction fabrication process suitable for qubits with long coherence times. Here, we extend the overlap junction fabrication process to micrometer-scale junctions. This allows us to fabricate other superconducting quantum devices. For example, we demonstrate an overlap junction-based Josephson parametric amplifier that uses only two layers. This efficient fabrication process yields frequency-tunable devices with negligible insertion loss, a gain of ∼30 dB, and quantum limited noise performance. Compared to other processes, the overlap junction allows for fabrication with minimal infrastructure, high yield, and state-of-the-art device performance.

Ultra-compact and broadband silicon polarizer employing a nanohole array structure.

An ultra-compact and broadband transverse magnetic (TM)-pass polarizer is experimentally demonstrated using a photonic crystal nanohole structure. By engineering the period of the circular holes, the fundamental transverse electric mode is suppressed due to the bandgap of the nanohole array, while the T M 0 mode propagates with a negligible insertion loss. Simulation results predict that the bandwidth of the device can reach 245 nm with a 33 dB polarization extinction ratio (PER). In the experiment, an insertion loss <1.2d B for the T M 0 mode and a PER over 20.8 dB are demonstrated in a 70 nm wavelength range from 1520 to 1590 nm, mainly limited by the grating couplers used for fiber-to-chip coupling. The fabricated device is compact with a total length of 7.21 µm.

A Slotline DC Block for Microwave, Millimeter, and Submillimeter Circuits

DC blocks are used frequently in planar circuits to enable separate dc voltage/current biasing of active components inserted along the transmission lines. In this letter, we present a slotline dc block design where the conductors of the transmission line can be physically broken while allowing the propagation of the RF signal across the discontinuity with negligible insertion loss. The dc block comprises two breaklines with narrow gaps, patterned on the two ground planes of a slotline with each breakline connected to an RF choke. The RF chokes present open circuit nodes that prevent the RF power from leaking into the breaklines gaps. We have fabricated and tested the dc block and demonstrated that the measured performance agrees very well with simulated results. The insertion loss was close to −0.5 dB in the designated range of 12–16 GHz, demonstrating that the RF leakage through the dc block is indeed negligible.

Polarization-Independent Mode-Evolution-Based Coupler for the Silicon-on-Insulator Platform

We demonstrate a polarization-independent mode-evolution-based coupler for the silicon-on-insulator platform. The measured coupler has negligible insertion loss over a bandwidth of about 100 nm, i.e., from 1500 to 1600 nm. The measured maximum power imbalances for the polarization-independent coupler are 1.2 and 0.2 dB for the fundamental transverse electric (TE $_\text{00}$ ) mode and the fundamental transverse magnetic (TM $_\text{00}$ ) mode, respectively. Our coupler also has a compact design footprint with mode-evolution region not more than ${75}{-\mu {\rm m}}$ long.

Tunable Photonic Radio-Frequency Filter With a Record High Out-of-Band Rejection

As radiofrequency filtering plays a vital role in electromagnetic devices and systems, recently photonic techniques have been intensively studied to implement radiofrequency filters to harness wide frequency coverage, large instantaneous bandwidth, low frequency-dependent loss, flexible tunability and strong immunity to electromagnetic interference. However, one crucial challenge facing the photonic radiofrequency filter (PRF) is the less impressive out-of-band rejection. Here, to the best of our knowledge, we demonstrate a tunable PRF with a record out-of-band rejection of 80 dB, which is 3 dB higher than the maximum value (~77 dB) reported so far, when incorporating highly selective polarization control and large narrow-band amplification enabled by stimulated Brillouin scattering effect. In particular, this record rejection is arduous to be achieved for a narrow passband (e.g., a few megahertz) and a high finesse in a PRF. Moreover, the proposed PRF is an active one capable of providing negligible insertion loss and even signal gain. Tunable central frequency ranging from 2.1 to 6.1 GHz is also demonstrated. The proposed PRF will provide an ultra-high noise or clutter suppression for harsh electromagnetic scenarios, particularly when room-temperature implementation and remote distribution are needed.

ANALYSIS OF COMPLEMENTARY BEAM STRUCTURED RF MEMS SWITCH FOR WIRELESS APPLICATIONS

This paper analysis the performance of a RF MEMS switch having a complementary beam structure operating at frequency ranging from 0 to 12GHz, which facilitates its application in the field of wireless mobile communication. This design is a modified cantilever beam forming a complementary structure with an easy fabrication process to implement. The switch is designed in form of a meander beam spring type in order to lower the spring constant there by achieving a relatively less pull-in voltage for actuation. The simulated results show a pull-in voltage of about 4V with the complementary cantilever beam structure. RF analysis shows a negligible insertion loss of -0.113dB and -7.181dB in the up-state of the switch from 0 to 12GHz. The isolation in the up-state was -57.62dB at 12GHz.

HIGH-PERFORMANCE LPF USING COUPLED C-SHAPE DGS AND RADIAL STUB RESONATORS FOR MICROWAVE MIXER

A high-performance microstrip low-pass filter (LPF) with low cutoff frequency, negligible passband insertion loss, very sharp transition band, and deep ultra-wide stopband is designed, fabricated and measured. The presented filter is realized using three types of resonators which are coupled C-shape defected ground structure (C-CDGS), mirrored series-resonant branch loaded by radial stub and high impedance line loaded by radial stub. A novel equivalent circuit model of the C-CDGS resonator is created, and its corresponding parameters are also extracted. The proposed filter is experimentally verified through the measured results which show good agreement with electromagnetic simulations.

Ring-Shaped Substrate Integrated Waveguide Wilkinson Power Dividers/Combiners

This paper proposes and presents a class of substrate integrated waveguide (SIW) power dividers/combiners based on a modified Wilkinson architecture. The proposed design consists of a ring-type circuit of 1.5 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> length with three waveguide ports. Impedance variation without affecting cutoff frequency and integration of isolation resistance are the two major limitations in connection with the design of SIW Wilkinson structures. Central ring part with different thickness ensures different impedance in the first proposed scheme while the half-mode SIW in the second option. As for the second limitation, the optimal configuration of integrating the isolation resistance is studied. A version without resistance is also examined using a broad-wall series slot. To validate the proposed concept, a bilayered circuit with standard Printed circuit board prototype was fabricated and measured. A table summarizing performances of all the proposed circuits shows a bandwidth of around 25% at the 10 dB reference. A negligible additional insertion loss is observed. The proposed design techniques are found useful at millimeter-wave frequencies where reduced physical dimensions make a circuit configuration suitable for low-cost implementation. This concept is also valid for rectangular waveguide counterparts.

RF-MEMS packaging by using quartz caps and epoxy polymers

This work reports on RF MEMS chip capping to protect sensitive devices by quartz caps having a cavity to enclose MEMS devices and an epoxy film polymer as a sealing ring. Full hermeticity is not possible due to the permeability of polymer but the goal to protect the mobile parts of the devices during dicing and assembling was achieved. Good RF MEMS devices are produced by die-to-die bonding and a reliable fabrication process is defined while wafer-to-wafer process still needs improvement to increase the fabrication yield. In this paper the fabrication process for both die-to-die and wafer-to-wafer 0-level capping is presented. Good adhesion of caps to the substrate is demonstrated by shear tests, while RF measurements on CPW lines indicate a negligible insertion loss increase. Capping of both capacitive and ohmic contact switches is reported showing no loss of functionality but a modification of actuation voltage induced by thermal treatment.

Mid-infrared wavelength division (de)multiplexer using an interleaved angled multimode interferometer on the silicon-on-insulator platform

A low-cost and high-performance wavelength division (de)multiplexing structure in the mid-IR wavelength range is demonstrated on the silicon-on-insulator platform using an interleaved angled multimode interferometer (AMMI). As compared to a single AMMI, the channel count was doubled and the channel spacing halved with negligible extra insertion loss and crosstalk and with only a slight increase in device footprint. The device requires only single lithography and etching steps for fabrication. Potential is also shown for achieving improved performance with further optimized design.

CB-CPW based Wide Band Bandpass Filter using Open-Stub Resonator

In this paper one conductor back coplanar waveguide based wide band bandpass filter is designed with end-coupled λ/4 open-stub resonator at the operating frequency 2.5 GHz. This proposed BPF structure exhibits negligible passband insertion loss of 0.2 dB, 100 % fractional bandwidth at −3 dB, sharp transition from passband to stopband, wide attenuation bandwidth of 4 GHz. This structure is simple in design with reduced size and provides slow-wave characteristics. This designed BPF is used for almost 2.5 GHz band around central frequency, almost no dispersion or scattering other than 0.5 ns group delay. Finally, the proposed structure has been fabricated and measured. There is a good agreement between the simulated and measured result. Therefore, the proposed filter is applicable in our modern microwave and millimetre wave communication systems due to its characteristics.

Nonreciprocal switching thresholds in coupled nonlinear microcavities

A concept for the design of nonlinear optical diodes is proposed that uses the multistability of coupled nonlinear microcavities and the dependence of switching thresholds on the direction of incidence. A typical example of such a diode can be created by combining two mirror-symmetric microcavities where modes of the opposite parity dominate. It is shown that a strong nonreciprocal behavior can be achieved together with a negligible insertion loss. To describe the dynamical properties of such systems, a model based on the coupled-mode theory is developed, and a possible implementation in the form of multilayered structures is considered.

Design of a Quasi- elliptic Lowpass Filter using A New Defected Ground Structure and Capacitively Loaded Microstrip Line

The modern microwave and millimeter wave communication system demands good filtering characteristics with compact sizes. In this paper the attention has been given towards the design of a good elliptical lowpass filter with sharp transition between passband and stopband, negligible passband insertion loss and wide stop band. A new defected ground structure (DGS) consisting of two square slots connects with a rectangular slot by two thin transverse slots underneath a microstrip line is proposed. In the frequency characteristics of proposed unit pattern provides an attenuation zero close to an attenuation pole. As a result, better transition sharpness, lower passband insertion loss and broader stopband are observed compares to dumbbell DGS. An equivalent lumped L-C network is proposed to model the introduced DGS unit and corresponding L-C parameters are extracted. A 3rd order quasi-elliptic lowpass filter with 1.4 GHz cut- off frequency, 1.7 GHz attenuation pole frequency, negligible passband insertion loss, almost 100 dB/GHz sharpness factor and 1.56GHz passband bandwidth (at -15 dB) is designed by cascading three investigated DGS units of different dimensions under capacitively loaded microstrip line.