mW Input Research Articles

PENGARUH PEMBEBANAN TERHADAP EFISIENSI DAN SUSUT UMUR TRANSFORMATOR STEP UP 6kV / 70kV DI PLTU SUMBAWA BARAT UNIT 1 DAN 2 2×7 MW PT.PLN (PERSERO) UPK TAMBORA

This study aims to determine the magnitude of the fluctuating load factor on the efficiency and loss of life of the 6kV/70kV transformer and to determine the optimal load in order to obtain the best efficiency and minimize loss of life. The method used in this study is a quantitative research method. The results showed that the highest efficiency of PLTU Unit 1 was at 93.3% with an output power of 5.8 MW and an input power of 6.21 MW, while the lowest was at 83.9% with an output power of 5.5 MW and a power 6.55 MW input. The highest efficiency of PLTU Unit 2 is at 95.7% with an output power of 5.5 MW and an input power of 5.75 MW, while the lowest is at 61.03% with an output power of 3.3 MW and an input power of 5.41. MW. Meanwhile, the transformer life for Unit 1 PLTU Sumbawa Barat is 0.0469 hours/day with an average load of 5.8 MW, while for Unit 2 it is 0.0311 hours/day with an average load of 5.2 MW. The size of the loss of life of the transformer depends on the given load, the greater the load, the greater the loss of life. In this case, the load for Unit 1 is higher than for Unit 2, so it can be seen that the life loss of the Unit 2 transformer is smaller. While the optimal load on the PLTU is in the position of 80-85% of its capacity. The results of this study are expected to be a material consideration for the Sumbawa power plant to better distribute and optimize the load so that there is no imbalance between the transformer capacity and the power produced and perform routine transformer maintenance to reduce losses that occur.

Investigation of dual-band antenna with low-SAR characteristics for bidirectional brain-machine interface applications

In this paper, we propose an innovative dual-band printed monopole antenna (PMA) for bidirectional brain-machine interface (Bi-BMI) application. The proposed antenna configuration contains of a square radiator with a pair of rectangular slots and an inverted U-shaped slot and a truncated ground plane with a pair of L-shaped slots, which provides two usable radiating bands for down-link data transferring around 2.3–2.5 GHz and for up-link data transferring 3.21–9.03 GHz. By inserting two rectangular slots surrounded by a modified inverted U-shaped slot with modified dimensions on the radiating square patch and also by cutting two L-shaped slots, new resonances are created and therefore much wider impedance bandwidth can be generated at both lower and higher bands. Despite recently reported antenna designs in the literature, the proposed antenna demonstrates wideband radiative characteristics even at higher frequencies, and also the specific absorption rate (SAR) level in 1 mW input power case is satisfactory less than 0.4 W/kg in the whole radiating band. The designed antenna has a compact configuration and small size. Simulated and measured S-parameter and radiation patterns results are demonstrated to confirm the utility of the designed antenna configuration for brain machine interface application.

Antenna-integrated silicon–plasmonic graphene sub-terahertz emitter

Photo-mixing with its advantages of ultra-large bandwidth and precise tunability has emerged as an important technique for terahertz (THz) wave generation. Recently, graphene photodetectors exhibiting a large bandwidth are expected to further boost the development of integrated THz emitters. Here, we fabricate a sub-THz emitter based on a large-bandwidth silicon–plasmonic graphene (SPG) photodetector integrated with a broadband rounded bow-tie THz antenna. The SPG sub-THz emitter is experimentally demonstrated to emit sub-THz waves with a radiation spectrum from 50 to 300 GHz. A maximum sub-THz emission power of 5.4 nW is obtained at 145 GHz with only 3 mW input light power. The SPG sub-THz emitter can be fabricated by a CMOS-compatible process, which offers enormous opportunities for its use in a variety of THz applications.

A comparative simulation study on lateral and L-shaped PN junction phase shifters for single-drive 50 Gbps lumped Mach–Zehnder modulators

We present a comparative study of lateral and L-shaped PN junction Si optical phase shifters for Mach–Zehnder modulators in Si photonics based on TCAD simulation. First, we introduce an easy fabrication method for L-shaped PN junctions by inverting dominant dopant type in Si. Then, we present the quantitative comparison of Si optical phase shifters. The L-shaped PN junction device shows the larger modulation efficiency of VpiL and the lower optical phase shifter loss compared to the lateral one. The VpiL for the vertical one is 0.89 Vcm, nearly half that of the lateral one, 1.76 Vcm at the same optical phase shifter loss, 10.5 dB cm−1. Finally, taking advantage of single-drive configuration and optimizing input characteristic impedance, the large-signal simulation with 1 mW input power and a 500 μm phase shifter shows the dynamic optical modulation amplitude of 0.22 mW for the vertical one, which could be a promising solution for a compact device footprint without a traveling wave electrode.

A 140 GHz high efficiency frequency doubler based on a physical‐based SDD model of SBD

SummaryIn this paper, a physical‐based SDD (symbolically defined devices) model of SBD (Schottky barrier diode) is proposed, in which conventional C‐V characteristics of diode SPICE model are modified by terahertz C‐V characteristics obtained by physical‐based simulation. Detail modeling method and design process are introduced in detail. To verify the accuracy of the SDD model, a 140 GHz high efficiency doubler is designed, fabricated, and measured. The measured maximum efficiency is 34.3% under 90 mW input power, and the 3 dB bandwidth is about 7 GHz, which agrees well with the simulated results. The proposed physical‐based SDD model is demonstrated to be more accurate than traditional diode SPICE model.

Cr3+‐Doped Sc‐Based Fluoride Enabling Highly Efficient Near Infrared Luminescence: A Case Study of K2NaScF6:Cr3+

AbstractThe development of highly efficient and thermally stable broadband near‐infrared (NIR) luminescence materials is a great challenge to advance the next‐generation smart NIR light source. Benefitting from the low phonon energy and relatively weak electron phonon coupling effect of the fluoride, K2NaScF6:Cr3+ phosphor is designed and obtained, which demonstrates a full width at half maximum of 100 nm peaking at ≈765 nm. Upon blue light excitation, the phosphor exhibits a high quantum efficiency of 74% and its emission intensity at 150 °C can keep 89.6% of the initial value at 25 °C. An NIR output power of 159.72 mW (input electric power, 1094 mW) with a high photoelectric conversion efficiency of ≈14.60%, light‐emitting diode (LED) device is presented based on this K2NaScF6:Cr3+ phosphor. Furthermore, applying the high‐power NIR phosphor‐converted LED device as lighting source, clear and quick veins imaging and recognition in fingers, palm, wrist, and arm of the human hand are first realized, suggesting K2NaScF6:Cr3+ phosphor has high promise in practical applications.

Human RF-EMF Exposure Assessment Due to Access Point in Incoming 5G Indoor Scenario

The study aimed at expanding the knowledge about the assessment of radio-frequency electromagnetic fields (RF-EMF) exposure, considering the novelties introduced by the incoming 5G networks. Specifically, a possible future case of indoor exposure scenario is investigated, where the presence of a 5G access point (AP) in a room is simulated. The AP was modelled by two different indoor uniform planar array (UPA) antennas at 3.7 GHz and at 14 GHz, to evaluate how the beamforming and the higher frequency use could impact the exposure levels. Different scenarios were evaluated, considering the maximum antenna gain, two different human computational models, an adult model and a child one, and by varying the distance and the orientation between the UPA antenna and the two models head. All the simulations were conducted using the Sim4Life platform and in particular the exposure levels were expressed by the specific absorption rate averaged on 10 g of tissue (SAR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10g</sub> ), which was analyzed for the skin and for some specific tissues. The work underlined that the highest SAR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10g</sub> values were obtained in the head area for all scenarios, with the skin SAR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10g</sub> highest peaks when the UPA is placed laterally to the human model (195.73 mW/kg and 223.29 mW/kg for the adult and child model, respectively, for 100 mW input power). Furthermore, the work permitted to highlight that the SAR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10g</sub> exposure levels are slightly higher for the child model, compared to the adult one and that the distance between the UPA antenna and the human models could greatly lower the SAR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10g</sub> levels. At last, it was found that the SAR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10g</sub> exposure levels obtained with the UPA antenna at 14 GHz were lower than the ones at 3.7 GHz, although further investigations will be necessary.

Sub-milliwatt optical frequency combs in dual-pumped high-Q multimode silicon resonators

We experimentally study the generation of optical frequency combs (OFCs) in dual-pumped high-quality factor (&amp;gt;106) multimode silicon racetrack resonators and show that sub-milliwatt (0.3 mW) input pump powers were sufficient to produce six-order OFC generation with eleven peaks, even in waveguides with normal dispersion. The low pump power and enhanced efficiency of the OFC generation can be attributed to mode coupling between two mode families of the multimode resonator, which acts to change the effective magnitude and the sign of the local dispersion of the resonator. We experimentally observed that the OFC generation had 3.6 times more peaks and 12.1 dB higher conversion efficiency than that without any bias. We compared the efficiencies of the OFC generation at different pump wavelengths within and beyond the mode coupling region. At low pump powers circulating in the resonator, pump wavelengths in the mode coupling regime produced 1.3 times more peaks and 8 dB enhancement in conversion efficiency than pumping beyond the mode coupling regime. The experimental results were consistent with the theoretical simulations by solving the modified Lugiato–Lefever equation.

Anomalous thermoacoustic effect in topological insulator for sound applications

Topological insulators possess unique surface states, which can be very useful for low power electronics. Most research on topological insulators focuses on their fundamental physical properties, and until now, there has been little work on their practical applications. Here, we extend the application of topological insulators to the field of acoustics. We show that topological insulators can be used for sound source applications using a large area of Bi2Se3. The sound pressure level (SPL) can reach up to 30 dB with an 85 mW input at a measured 1 cm distance at room temperature. More interestingly, an anomalous valley with a sound pressure level (SPL) drop of ∼9 dB occurs at 21.5 kHz in a Bi2Se3 topological insulator, which is not observed in monolayer graphene. This anomalous phenomenon is related to the unique surface and bulk states of Bi2Se3. A theoretical equivalent circuit model is built for a topological insulator and compared with that of graphene. Based on the equivalent circuit model combined with thermoacoustic sound-generation theory, such an anomalous thermoacoustic effect with an SPL valley at around 21.5 kHz can be simulated. Our work shows that topological insulators have potential as powerful sound sources, such as earphones and loudspeakers, and that the unique surface states are highly conducive to frequency-selected sound emission.

Cascaded Stokes and anti-Stokes laser based on an optical resonator with a self-assembled organic monolayer.

Due to their high circulating intensities, ultra-high quality factor dielectric whispering gallery mode resonators have enabled the development of low threshold Raman microlasers. Subsequently, other Raman-related phenomena, such as cascaded stimulated Raman scattering (CSRS) and stimulated anti-Stokes Raman scattering (SARS), were observed. While low threshold frequency conversion and generation have clear applications, CSRS and SARS have been limited by the low Raman gain. In this work, the surface of a silica resonator is modified with an organic monolayer, increasing the Raman gain. Up to four orders of CSRS are observed with sub-milliwatt (mW) input power, and the SARS efficiency is improved by three orders of magnitude compared to previous studies with hybrid resonators.

High optical damage threshold on-chip lithium tantalate microdisk resonator.

Lithium tantalate (LT) is one of the most attractive optical nonlinear materials, as it possesses a high optical damage threshold and great UV transparency (0.28-5.5 µm). Recently, optical grade LT nanoscale film was developed. Here a high-quality-factor (∼105) LT microdisk resonator based on LT-on-insulator (LTOI) film is fabricated by utilizing focused ion beam (FIB) milling. 2 µW output second-harmonic waves are achieved in the LTOI microdisk at about 500 mW input power. Cascaded third-harmonic generation is also observed in the fabricated device. This work may pave the way for LTOI in integrated photonic chips.

Impact of nonlinear effects on transmission losses of hollow-core antiresonant negative curvature optical fiber.

We investigate the impact of input pulse duration and peak power of a femtosecond laser on pulse broadening and propagation losses in selected hollow-core antiresonant fiber (HC-ARF). The mixed effects of strong self-phase modulation and relatively weak Raman scattering broaden the spectral width, which in turn causes a portion of the output spectrum to exceed the transmission band of the fiber, resulting in transmission losses. By designing and setting up a gas flow control system and a vacuum system, the nonlinear behavior of the fiber filled with different pressurized gases is investigated. The experimental results show that replacing the air molecules in the fiber core with argon can weaken pulse broadening and increase the transmittable peak power by 14 MW for a given 122 MW input, while a vacuum system can reduce the nonlinearity to a larger extent, therefore enhancing the transmission of HC-ARF by at least 26 MW.

Characterization of the Interdependence Between the Light Output and Self-Heating of Gallium Nitride Light-Emitting Diodes

Abstract With the advent of gallium nitride (GaN) as an enabling material system for the solid-state lighting industry, high-power and high-brightness light-emitting diodes (LEDs) with wavelengths ranging from near ultraviolet to blue are being manufactured as part of a tremendously large and ever-increasing market. However, device self-heating and the environment temperature significantly deteriorate the LED's optical performance. Hence, it is important to accurately quantify the LED's temperature and correlate its impact on optical performance. In this work, three different characterization methods and thermal simulation were used to measure and calculate the temperature rise of an InGaN/GaN LED, as a result of self-heating. Nanoparticle-assisted Raman thermometry was used to measure the LED mesa surface temperature. A transient Raman thermometry technique was utilized to investigate the transient thermal response of the LED. It was found that under a 300 mW input power condition, self-heating is negligible for an input current pulse width of 1 ms or less. The temperature measured using nanoparticle-assisted Raman thermometry was compared with data obtained by using the forward voltage method (FVM) and infrared (IR) thermal microscopy. The IR and Raman measurement results were in close agreement whereas the data obtained from the widely accepted FVM underestimated the LED temperature by 5–10%. It was also observed that an increase in environment temperature from 25 °C to 100 °C would degrade the LED optical power output by 12%.

Ti Hot Electron Bolometers with Johnson Noise Readout for Terahertz Radiation Detection

A hot electron bolometer (HEB) with Johnson noise readout is an attractive technique for radiation detection due to its high sensitivity, wide operating temperature range, and large dynamic range. In this paper, we present the development of a terahertz HEB based on Johnson noise readout. The HEB consists of a titanium microbridge connected to two high-energy-gap niobium contacts for confining hot electrons. We measured the thermal conductance and noise equivalent power (NEP) of the HEB at different bath temperatures. We find that the thermal conductance due to the electron–phonon interaction increases with temperature as T2.5. At 3.0 K, the thermal conductance is found to be 37.9 ± 1.4 nW/K and the electrical NEP is as low as 23.0 ± 0.8 pW/$$ \sqrt {\text{Hz}} $$. In addition, we find that the HEB works efficiently up to 15 μW input power.

Quasi-Phase Matched Second Harmonic Generation in Plasmonic–Organic Hybrid Structures

In this article, we propose the design and analyze a plasmonic-organic-hybrid (POH) waveguide structure for efficient forward and backward second harmonic generation (SHG) to bridge the mid-infrared (IR) to near-IR. The required phase matching is satisfied by quasi-phase matching (QPM) technique through periodically altering the material of the metal-insulator-metal slot region between a nonlinear polymer (with second-order nonlinear coefficient of χ (2) ≠ 0) and Al2O3 (with χ (2) = 0) leading to modulation of χ (2) coefficient along the propagation direction. The strong field confinement offered by surface plasmon polaritons (SPPs) significantly enhances the normalized efficiency up to 1.75 × 106 W−1cm−2 in the case of backward SHG over a short device length of 17 μm with only 20 mW input power. Also, a slightly lower efficiency is achieved for forward configuration with broadband response, high fabrication tolerance, and small temperature-variation sensitivity. Furthermore, our proposed structure is based on standard nanofabrication technologies and can be used for all-optical signal processing, low-noise detection of a mid-IR signal in the near-IR windows, and (mirrorless) optical parametric oscillator.

Functionalized polymer waveguide optical switching devices integrated with visible optical amplifiers based on an organic gain material

In this work, polymer waveguide based optical switching devices integrated with visible optical amplifying waveguides based on an organic gain material are designed and fabricated. The gain compound is a red emissive oligomer, with good dispersibility in organic polymer matrices. Optical characteristics and thermal stabilities of the active polymer waveguide core and cladding materials are analyzed. Optical gain of the amplifier operating at 650 nm red signal wavelength with 0.1 mW input power is found to be over 3.5 dB under only 1.6 mW pumping power with 532 nm green excitation light. The on-off response time of the integrated thermo-optic switch applied is measured to be 600 μs, with switching extinction ratio of 20 dB and electric switching power of 18.5 mW. The integrated switching device capable of optical gain will be suitable for applications to optical communications at the visible wavelength range involving plastic optical fiber systems.

Development of High Power 220 GHz Frequency Triplers Based on Schottky Diodes

In this paper, the development of two high power 220 GHz frequency triplers is proposed. The GaAs Schottky diodes with six nodes are applied to realize high efficiency 220 GHz tripler, while the application of GaN Schottky diodes with eight nodes is another attempt to improve power handling of the 220 GHz tripler. To reduce thermal effect of high power multipliers, the AlN substrates with high thermal conductivity are applied to provide better heat dissipation at the diode areas. A combination of electrical and thermal model of the Schottky diodes is established while the optimization of 220 GHz triplers are realized with 3D electromagnetic (EM) simulation and harmonic balanced simulation. Good agreement is achieved between the simulated results based on electro-thermal model and measured performances of the triplers. At room temperature, peak efficiency of the tripler based on GaAs Schottky diodes is 17.8%, while the maximum output of the tripler is 38.2 mW with 300 mW input power. As for the 220 GHz GaN Schottky diode tripler, measured results show that the maximum power handling is beyond 400 mW. The peak efficiency and maximum output are 4.7% and 18.4 mW, respectively. The proposed methods of developing high power multipliers can be applied in higher frequency band in the future.

A 300 GHz power‐combined frequency doubler based on E‐plane 90°‐hybrid and Y‐junction

AbstractIn this article, a 300 GHz power‐combined frequency doubler using two chips in a single waveguide block is developed to acheive high power handling capability. Each doubler chip integrated with six diodes on a 5‐μm‐thick GaAs membrane is manufactured by the LERMA‐C2N Schottky process. In the power combining architecture, the input wave is split into two paths with a 90° relative phase shift by using a 90° hybrid coupler, and the in‐phase E‐field power combining between the output ports is provided by an E‐plane Y‐junction. This doubler can enjoy comparable performance of bandwidth and efficiency as the single‐chip version except with the twice input power handling. Partial results including ~8 mW output power and ~15% efficiency have been delivered in the band of 260‐310 GHz when pumping with 20‐60 mW input power, which indicates that this dual‐chip doubler can work availably. Such E‐plane power‐combined doubler can be further served to drive high‐power terahertz multiplier chains, and also pump multipixel heterodyne detectors.

A Reconfigurable Passive RF-to-DC Converter for Wireless IoT Applications

In this brief, we present a reconfigurable rectifier, which makes it feasible to harvest energy with net-zero energy consumption, i.e., without draining power from battery, in a wide input power range. The proposed topology can operate with low input power signals and can be fine-tuned for a specific operating frequency in a wide frequency range from several MHz to GHz in remotely powered systems. A prototype is fabricated in 0.35- $ {\mu }\text{m}$ standard CMOS process and occupies 0.019 mm2. Although the proposed rectifier supports four different rectifier topologies, on silicon it only occupies the footprint of a single rectifier. At 13.56 MHz with 2.2 mW input power, the four-switch rectifier topology yields 82% power conversion efficiency (PCE), while the hybrid topology (diodes + switches) provides 81% PCE at 11.2 mW input power. The rectifier operates with input power as low as 1.1 mW, at which level the PCE is still reasonable at 65.2%. This allows a wireless device at low power level to operate at extended read range. This reconfigurable rectifier is especially suitable for Internet of Things mobile application, where the power of the incoming signal changes by the distance between the power source and the device.

(Invited) Planar Thermoelectric Micro Refrigerators Based on Nanograined SiGe Thin Films

Rapid development of modern miniaturized microelectronic and optical devices demands for low-power and fast-response on-chip refrigeration to reduce thermal noise and improve device lifetime. Thermoelectric microrefrigerators offer an attractive all-solid-state solution with many prominent merits. Conventional thermoelectric microrefrigerators widely adopt integrated-circuit (IC)-incompatible toxic heavy metal compounds as thermoelectric elements, rendering them unsuitable for on-chip integration. Here we developed free-standing planar thermoelectric microrefrigerators based on nanograined SiGe thin films. The novel support-free design and the record high performance of the nanograined SiGe thin films lead to significant improvement in the cooling performance. A maximum cooling temperature of 10.3 K together with a response time of 16 ms has been achieved in the single-stage microrefrigerator with a power consumption of 56 μW near room temperature while a maximum cooling temperature of 11.2 K can be achieved in the two-stage refrigerator with 0.41 mW input power. The cooling temperatures of the SiGe microrefrigerators also improve with the increasing ambient temperature, reaching up to 15 K and 17 K for the single and two-stage microrefrigerators respectively at 340 K. These SiGe thin-film devices can deliver cooling performances comparable to the records for traditional heavy-metal-based microrefrigerators while providing excellent IC compatibility and almost one to two orders of magnitude higher cooling temperature to power consumption ratios (184 K/mW), rendering them ideal candidates for low-power on-chip refrigeration.