dBm Input Research Articles

Synthesis and characterization of Er2O3-doped Y2O3 nanoparticle incorporated optical fiber for use as optical amplifier

Erbium oxide (Er2O3)-doped optical fibers (EDF) are well-known for their applications in optical amplification at 1550 nm. In this study, we present the synthesis of Er2O3-doped yttrium oxide (Y2O3) nanoparticles (NPs) using a homogeneous coprecipitation technique and their integration into optical fibers for enhanced optical amplification. A series of NP samples with varying Y/Er molar ratios were synthesized to identify the optimal composition for incorporation into optical fibers. X-ray diffraction (XRD) analysis revealed that the nanoparticles crystallize in a cubic geometry (space group Ia3) with crystallite sizes ranging from 20 to 41 nm. These sizes increased approximately to 90 nm as the calcination temperature was raised from 1000°C to 1400°C. Field emission scanning electron microscopy (FESEM) corroborated the XRD results, while high-resolution transmission electron microscopy (HRTEM) confirmed the crystalline structure and an average particle size of approximately 100 nm. Photoluminescence studies showed that emission and excitation intensities were functions of the Y/Er molar concentration ratio and calcination temperature, with the lifetime extending up to 6.86 ms for a sample with a 0.25:0.01 Y2O3:Er2O3 ratio calcined at 1400°C. To assess the performance of the synthesized NPs, an optical preform was prepared using the Vapor Phase Delivery (VPD) method combined with the Solution Doping (SD) technique. The preform was then drawn into fiber, and its amplification performance was evaluated. The resulting fiber demonstrated efficient amplification with a gain of 14.9 dB with respect to 0 dBm input signal at 1550 nm under 150 mW pump power from 9 m active fiber, indicating its potential as a gain medium for constructing erbium-doped fiber amplifiers (EDFAs).

A 2.4 GHz High-Efficiency Rectifier Circuit for Ambient Low Electromagnetic Power Harvesting.

A novel 2.4 GHz high-efficiency rectifier circuit suitable for working under very-low-input electromagnetic (EM) power conditions (-20 to -10 dBm) is proposed for typical indoor power harvesting. The circuit features a SMS7630 Schottky diode in a series with a voltage booster circuit at the front end and a direct-current (DC)-pass filter at the back end. The voltage booster circuit consists of an asymmetric coupled transmission line (CTL) and a high-impedance microstrip line (of 100 Ω instead of 50 Ω) to significantly increase the potential at the diode's input, thereby enabling the diode to operate effectively even in very-low-power environments. The experimental measurements show that the microwave direct-current (MW-DC) conversion efficiency of the rectifier circuit reaches 31.1% at a -20 dBm input power and 62.4% at a -10 dBm input power, representing a 7.4% improvement compared to that of the state of the art. Furthermore, the rectifier circuit successfully shifts the input power level corresponding to the peak rectification efficiency from 0 dBm down to -10 dBm. This design is a promising candidate for powering low-energy wireless sensors in typical indoor environments (e.g., the home or office) with low EM energy density.

A Prediction about Radio Frequency Envelope Detectors for Implementing a 2.4 GHz Rectenna for IEEE 802.15.4 with MOS Transistors

This study introduces a rectenna, functioning as an RF envelope detector, utilizing a 16 nm bulk MOS transistor (metal-oxide-semiconductor field-effect transistor) for nonlinear detection. A circuit architecture is presented alongside a detailed design methodology and simulations. The detector efficiently demodulates a 2.4 GHz OOK (On/Off Keying) encoded signal, comprising a 32-bit word, within 320 μs. Remarkably, the circuit operates passively, requiring no voltage supply or bias current, and functions effectively with −53 dBm input power at the antenna. This capability enables the decoding of 32-bit unsigned integer radio packets as a wakeup radio event. The effectiveness of the envelope detector is substantiated through comprehensive simulations.

A 40.3–50.5 GHz locking range transformer‐based injection‐locked frequency divider utilizing a high third harmonic rejection buffer

AbstractInjection‐locked dividers feature ultrahigh operating frequency, low power consumption, and low phase noise, making them suitable for Q‐band phase‐locked loop. This paper presents a transformer‐based divide‐by‐4 injection locking frequency divider with a high third harmonic rejection buffer based on 40‐nm CMOS technology. Employing a fourth‐order transformer resonator enhances the third‐order harmonic amplitude, increasing the injection efficiency and expanding the locking range. The proposed high third harmonic rejection buffer using a source degeneration inductor can effectively suppress the output of the third harmonic caused by the resonator, ultimately yielding a clean fundamental frequency signal. Simulation results demonstrate that the proposed divide‐by‐4 injection‐locked frequency divider (ILFD) achieves a locking range of 10.2 GHz (from 40.3 to 50.5 GHz) with 0 dBm input signal. The core divide‐by‐4 ILFD circuit consumes 4.6 mW power with a 0.9 V supply and occupies an area of 0.026 mm2.

Modeling optimization design and amplification characteristics of O-band irregular Bragg bismuth-doped fiber amplifier

In recent years, O-band bismuth-doped fiber amplifier (BDFA) have been rapidly developed due to the fluorescence properties of bismuth-doped glass in the near-infrared (NIR) band, while there are still few studies on bismuth-doped fibers (BDF) with large mode fields as of now. In addition, although the use of a double-pass structure on the amplifier can lead to gain improvement, this also deteriorates the noise figure (NF). Therefore, the study of bismuth-doped fibers with large mode-field areas is a promising path to develop high-performance BDFA. In this work, taking a commercial bismuth-doped fiber as an instance, we first measured the refractive index distribution of the BDF in the O-band using a self-developed fiber refractive index tester, and thereby obtained its actual mode-field area. Then, based on this we further propose an irregular Bragg bismuth-doped fiber with the refractive index growing layer by layer. The results suggests that the effective mode-field area of this fiber reaches 401 um2 at 1320 nm, which is nearly 5.8 times that of a common single-mode BDF. Finally, we performed numerical simulations of the amplification performance based on this fiber. Under the condition of total pumping power of 8 W, the signal with −20 dBm input power obtains a gain of more than 54 dB and an NF of less than 5 dB at 1320 nm wavelength. This work demonstrates the great potential of this Bragg bismuth-doped fiber as an O-band high-gain amplifier and high-power laser.

Dual-band low-power RF-to-DC signal converter circuits for energy harvesting

This article presents dual-band low-power, high-sensitive radio-frequency (RF)-to-direct current (DC) signal converter circuits, operating at 2.45 and 5.5 GHz bands, for radio frequency energy harvesting applications. In particular, it focuses on the lumped element and microstrip transmission line model circuits. The lumped element RF-to-DC converter circuit is composed of a dual-band impedance matching circuit, voltage-doubler rectifier, and DC-pass filter with a resistive load of 5 kΩ. This converter circuit gives a DC output voltage of 48 mV at 2.45 GHz and 25 mV at 5.5 GHz on −25 dBm input power. Maximum conversion efficiency is 47% at the 2.45 GHz band and 27% at the 5.5 GHz band when the input power is set to −10 dBm. Circuit design steps, matching conditions, performance parameters, and so on, are presented using Advanced Design System simulation. To validate the concept of the lumped element model, a microstrip transmission line RF-to-DC converter model is simulated and fabricated. It also composes of a dual-band matching network, voltage-doubler, and DC-pass filter with a load resistance of 5 kΩ. At a low input power of −18 dBm, it gives an output voltage of 21 mV in measurement. An appropriate match between the simulation and measurement is noted.

A peak enhancement of frequency response of waveguide integrated silicon-based germanium avalanche photodetector

Avalanche photodetectors (APDs) featuring an avalanche multiplication region are vital for reaching high sensitivity and responsivity in optical transceivers. Waveguide-coupled Ge-on-Si separate absorption, charge, and multiplication (SACM) APDs are popular due to their straightforward fabrication process, low optical propagation loss, and high detection sensitivity in optical communications. This paper introduces a lateral SACM Ge-on-Si APD on a silicon-on-insulator (SOI) wafer, featuring a 10 μm-long, 0.5 μm-wide Ge layer at 1310 nm on a standard 8-inch silicon photonics platform. The dark current measures approximately 38.6 μA at −21 V, indicating a breakdown voltage greater than −21 V for the device. The APDs exhibit a unit-gain responsivity of 0.5 A/W at −10 V. At −15 V, their responsivity reaches 2.98 and 2.91 A/W with input powers of −10 and −25 dBm, respectively. The device's 3-dB bandwidth is 15 GHz with an input power of −15 dBm and a gain is 11.68. Experimental results show a peak in impedance at high bias voltages, attributed to inductor and capacitor (LC) circuit resonance, enhancing frequency response. Furthermore, 20 Gbps eye diagrams at −21 V and −9 dBm input power reveal signal to noise ratio (SNRs) of 5.30. This lateral SACM APD, compatible with the stand complementary metal oxide semiconductor (CMOS) process, shows that utilizing the peaking effect at low optical power increases bandwidth.

Evaluation of Recycled Cardboard Paper as an Eco-Friendly Substrate for Rectenna and Ambient Radio Frequency Energy Harvesting Application

Developers of electronics for the Internet of Things are considering nonstandard substrate materials like recyclable, low-cost, and eco-friendly cardboard paper. From this perspective, this article reviews the design and experimental results of a 2D-rectenna for scavenging radio-frequency energy at 2.45 GHz on various cardboard paper substrates for both the antenna and rectifier. Four types of recycled cardboard material, each with different thicknesses, air gaps, and surface roughness, are selected for characterization. A linearly polarized rectangular microstrip patch antenna with microstrip transmission feeding is adopted for ease of fabrication. At 2.45 GHz, the antenna has a simulated and measured global gain of 2.98 dB and 2.53 dB, respectively, on a 2.2 mm thick cardboard material. The rectifying element consists of a voltage-doubler configuration connected through a T-matching network to the antenna. At low RF input power (−10 dBm), the maximum available DC output power is experimentally evaluated at 1.73 μW, 7.5 μW, and 8.5 μW for HSMS-2860, HSMS-2850, and SMS7306-079L diodes, respectively. The respective rectifiers with diodes SMS7306-079L, HSMS-2850, and HSMS-2860 exhibit optimal load values of 2 kΩ, 2.6 kΩ, and 8 kΩ. The rectifier designed using the SMS7306-079L diode experimentally reaches a maximum power conversion efficiency (PCE) of 14.2% at −5 dBm input power when the optimal load value is 1.5 kΩ.

High-gain ultra-wideband bismuth-doped fiber amplifier operating in the O + E + S band.

We present a double-pass bismuth (Bi)-doped fiber amplifier (BDFA) providing high-gain wideband amplification from 1330 to 1480 nm. A peak gain of 38 dB with 4.7 dB noise figure (NF) was obtained at 1420 nm for a -23 dBm input signal, with >20 dB gain from 1335 to 1475 nm. We achieved 30 and 21.5 dB peak gains with 122 nm (1341-1463 nm) and 140 nm (1333-1473 nm) 6 dB-gain bandwidth for -10 and 0 dBm input signal, respectively. For a 0 dBm signal, the power conversion efficiency (PCE) reached 23.7%, and the in-band optical-signal-to-noise ratio (OSNR) across the wideband BDFA was >44 dB. Also, the absorption and luminescence characteristics have been studied for different Bi-doped phosphosilicate fibers (BPSFs) fabricated in-house.

Dual Frequency Energy Harvesting System Based on Planar Inverted F-shaped Antenna

<p>With the expansion of Internet of things (IoT) scale and the extension of its application fields, node energy acquisition has become one of the constraints on the development and application of IoT technology. Wireless energy acquisition is faced with the challenge of how to enhance power conversion efficiency under low input power in the broadband range. This study aimed to improve the capability of energy collection and transmission in wireless communication, an efficient dual-frequency energy harvesting system was proposed, moreover a novel dual-frequency planar inverted-f antenna (PIFA) and its energy conversion circuit for Radio frequency (RF) energy harvesting were designed by studying the characteristics of ambient RF energy and antenna. The developed antenna is designed and manufactured for GSM 900mhz or DCS 1.8 GHz to harvest the ambient energy provided by nearby devices. It is proved that the new dual-frequency antenna still has high efficiency when the input power is less than -20 dbm, and can maximize the receiving energy. The system works with an energy conversion and storage module to convert weak signals into required voltages, the simulation and test results show that the maximum conversion efficiency of the prototype is about 65% at 920MHZ and 1.8GHz at -20 dBm input power.</p> <p> </p>

Optimizing High Data Rate Up to 2.5 Tbps Transmission using 64-Channel DWDM System with DCF and NRZ Modulation

Objectives: This study aims to enhance and optimize a modern communication system for high data rate transmission using Dense Wavelength Division Multiplexing (DWDM). The objectives include employing a 64-channel DWDM system, implementing different data speeds, and utilizing a dispersion compensation method. Methods: To achieve the objectives, we simulate and analyze the effects of Dispersion Compensation Fiber (DCF) in a DWDM system with 64 channels. The system employs Non-Return-to-Zero (NRZ) modulation format at varied bit rates and multiple energy levels. We propose a method for achieving data rates of 10 to 40 Gbps using NRZ modulation and Erbium-Doped Fiber Amplifier (EDFA) over a single-mode fiber transmission distance of 40 to 160 km, along with a dispersion compensation fiber of 8 to 32 km (DCF). The performance of the developed model is evaluated based on Quality Factor, Bit Error Rate (BER), Eye Height, and Threshold. These metrics are measured at two input energy levels from an optical power source, covering a communication capacity ranging from 0.625 Tbps to 2.5 Tbps. Findings: Through the simulations and analyses, we uncover the impact of dispersion and demonstrate the effectiveness of the proposed method in compensating for dispersion effects. Performance analysis of two different input transmitter power levels, -10 dBm is more efficient compared to 0 dBm input transmitter power in terms of bit error rate and quality factor. Novelty: This study presents a novel approach to improving modern communication systems by utilizing DWDM with a dispersion compensation method. The use of a 64-channel DWDM system, combined with the proposed NRZ modulation technique and dispersion compensation fiber, provides an efficient solution for achieving high data rates over long transmission distances while minimizing the effects of dispersion. The findings contribute to the advancement of communication systems for high data rate transmission. Keywords Dispersion effect, Bit Error Rate, Q-factor, Optisystem software, Erbium doped fiber amplifier

Electrical feedback system for enhancing the RF power of photodetector.

In this paper, we propose a system for enhancing the RF output power of the photodetector, especially the power of fundamental tune and second-order harmonic, by feeding back part of the RF signal through an electrical feedback circuit. As a result of bias modulation and opto-electric mixing, the RF output power can be effectively enhanced. The structure of uni-traveling carrier photodetector (UTC-PD) is employed in this work. With the RF enhancement system, the power of fundamental tune and second-order harmonic improve by 6.4 dB and 9.9 dB respectively, under the condition of 26 dBm input optical power, 3 V bias voltage, and 14 GHz input optical signal. Further, it was observed that third-order harmonic appeared under the influence of this system.

Microwave quantum diode

The fragile nature of quantum circuits is a major bottleneck to scalable quantum applications. Operating at cryogenic temperatures, quantum circuits are highly vulnerable to amplifier backaction and external noise. Non-reciprocal microwave devices such as circulators and isolators are used for this purpose. These devices have a considerable footprint in cryostats, limiting the scalability of quantum circuits. As a proof-of-concept, here we report a compact microwave diode architecture, which exploits the non-linearity of a superconducting flux qubit. At the qubit degeneracy point we experimentally demonstrate a significant difference between the power levels transmitted in opposite directions. The observations align with the proposed theoretical model. At − 99 dBm input power, and near the qubit-resonator avoided crossing region, we report the transmission rectification ratio exceeding 90% for a 50 MHz wide frequency range from 6.81 GHz to 6.86 GHz, and over 60% for the 250 MHz range from 6.67 GHz to 6.91 GHz. The presented architecture is compact, and easily scalable towards multiple readout channels, potentially opening up diverse opportunities in quantum information, microwave read-out and optomechanics.

High bismuth-doped germanosilicate fiber for efficient E + S-band amplification.

Bismuth-doped germanosilicate fiber (BGSF), the active media of fiber amplifiers, has attracted widespread attention. Here, we report a BGSF with a high bismuth concentration of 0.075 wt. % and achieve high-efficiency E + S-band amplification, which was prepared by the modified chemical vapor deposition (MCVD) process. The small signal absorption (SSA) and unsaturated loss (UL) of BGSF at 1310 nm are 1.32 and 0.11 dB/m, respectively. The results show a record with only 45 m BGSF was created, to the best of our knowledge, which provides a maximum gain of 39.24 dB with an NF of 6.2 dB at 1430 nm under -20 dBm input signal power.

EDFA with power pump laser in WDM Network design of 10GBPS transmission

Wavelength Division Multiplexing (WDM) that enabled optical networks are currently widely used in current telecommunications infrastructures and are anticipated to play a significant role in next-generation networks and the future Internet, supporting a wide range of services with a wide range of bandwidth, latency, reliability, and other feature requirements. In WDM networks, the input power of an optical transmitter is crucial; as a result, this results in a good output signal at the receiver side. The purpose of this paper is to design a WDM Optical Network in terms of length and pump power. The system is simulated using Opti-System software to achieve bit error rate (BER), quality factor, and output power of EDFA through optimized fiber length and pump power. In this analysis, the BER value, Q-factor and output of the system have been evaluated between 1550 and 1552nm with 0 dBm input signal power. EDFA length of 5km, power pump value of 500mv and 980nm frequency was set as reference in this study. This system was analysed using Opti-System simulation software at 10 Gigabits per second (10GBPS) transmission system. Result have shown that, min BER value shows a very significant increase at a 9-meter length and the Q-factor was rapidly decrease. The min BER value was in range 10-11 and 10-19 and Q-factor range 6.5 to 9.1 for 200mW to 8000mW power pump.

Circularly polarized metasurface antenna based on characteristic mode analysis for microwave energy harvesting

AbstractIn this paper, a circularly polarized metasurface antenna for microwave energy harvesting (MEH) is proposed. First, a 4 × 4 metasurface is analyzed and integrated with the microstrip slot based on characteristic mode analysis for broadband, low profile, and high gain metasurface antenna. The measured results show that the impedance bandwidth of the metasurface antenna is 1.82 GHz, the 3 dB axial ratio bandwidth is 0.96 GHz. Subsequently, a wideband rectifier for C‐band is fabricated and measured according complex impedance compression theory. The frequency of efficiency >50% is from 5.1 to 6.3 GHz with 17 dBm input power. Finally, the novel antenna and rectifier are connected as rectenna for MEH, which shows great potential due to the tunability of the polarization mode (right‐handed CP [RHCP]/left‐handed CP [LHCP]) and the flexibility of the structure.

Effects of Optical Sampling Pulse Power, RF Power, and Electronic Back-End Bandwidth on the Performance of Photonic Analog-to-Digital Converter.

The effects of optical sampling pulse power, RF power, and electronic back-end bandwidth on the performance of time- and wavelength-interleaved photonic analog-to-digital converter (PADC) with eight-channel 41.6 GHz pulses have been experimentally investigated in detail. The effective number of bits (ENOB) and peak-to-peak voltage (Vpp) of converted 10.6 GHz electrical signals were used to characterize the effects. For the 1550.116 nm channel with 5.2 G samples per second, an average pulse power of 0 to -10 dBm input to the photoelectric detector (PD) has been tested. The Vpp increased with increasing pulse power. And the ENOB for pulse power -9~-3 dBm was almost the same and all were greater than four. Meanwhile, the ENOB decreased either when the pulse power was more than -2 dBm due to the saturation of PD or when the pulse power was less than -10 dBm due to the non-ignorable noise relative to the converted weak signal. In addition, RF powers of -10~15 dBm were loaded into the Mach-Zehnder modulator (MZM). The Vpp increased with the increase in RF power, and the ENOB also showed an increasing trend. However, higher RF power can saturate the PD and induce greater nonlinearity in MZM, leading to a decrease in ENOB, while lower RF power will convert weak electrical signals with more noise, also resulting in lower ENOB. In addition, the back-end bandwidths of 0.2~8 GHz were studied in the experiments. The Vpp decreased as the back-end bandwidth decreased from 8 to 3 GHz, and remained nearly constant for the bandwidth between the Nyquist bandwidth and the subsampled RF signal frequency. The ENOB was almost the same and all greater than four for a bandwidth from 3 to 8 GHz, and gradually increased up to 6.5 as the back-end bandwidth decreased from the Nyquist bandwidth to 0.25 GHz. A bandwidth slightly larger than the Nyquist bandwidth was recommended for low costs and without compromising performance. In our experiment, the -3 to -5 dBm average pulse power, about 10 dBm RF power, and 3 GHz back-end bandwidth were recommended to accomplish both a high ENOB more than four and large Vpp. Our research provides a solution for selecting optical sampling pulse power, RF power, and electronic back-end bandwidth to achieve low-cost and high-performance PADC.

The Design of a 1-6 GHz Broadband Double-Balanced Mixer.

This brief proposes a 1-6 GHz broadband double-balanced mixer. On the basis of the standard Marchand balun mixer, two techniques to enhance the performance of the mixer are proposed. Firstly, by loading capacitors, the amplitude and phase imbalance of the balun at high frequencies are improved, thereby expanding the relative bandwidth of the mixer by 0.1. Secondly, by cascading a first-order LC filter at the intermediate-frequency (IF) port, the leakage of radio frequency (RF) and local oscillator (LO) signals at the IF port is reduced by approximately 8 dB and 7 dB, respectively. This brief analyzes the various parameters that affect balun indicators and designs a broadband balun with a double-layer spiral line structure. As a result of these technologies, a 1-6 GHz double-balanced mixer is realized. The chip area is 1.13 mm × 0.95 mm, and the isolation between the IF port and the RF port is 34 dB and yields 13.5 dBm input power at 1 dB compression point (IP1 dB). The chip is fabricated via the GaAs pHEMT process.

Radiation-resistant cerium co-doped erbium-doped fibers for C- and L-band amplifiers in a high-dose gamma-radiation environment.

We experimentally demonstrate a comparative study on the radiation-resistant cerium (Ce) co-doped erbium-doped fiber amplifiers (EDFAs) exposed to a high-dose gamma-radiation environment of 1.8 kGy/h dose rate in the C and L bands. Our results show that Ce is an effective co-dopant in the aluminosilicate EDFs for suppressing radiation-induced attenuation (RIA) of more than an order of magnitude lower than the Ce-free EDF. After exposure to a high-dose gamma-radiation of up to 10 kGy, the Ce co-doped EDF still exhibits good radiation tolerance, providing 41.6 ± 2.9 dB gain and 5 ± 0.8 dB NF from 1535-1560 nm for a -25 dBm input signal. In the L-band, we report, for the first time, the radiation-resistant EDFA with the radiation-induced gain degradation (RIGD) of 3.7 dB under 2.5 kGy irradiation and 4.4 dB under 10 kGy irradiation at 1600 nm. Also, the radiation-dependent gain coefficient and gain saturation were studied in the C and L bands. A comparison of different Ce co-doped EDFs exposed to different total gamma doses reveals the radiation impact on the amplifier performance, indicating the feasibility of using Ce co-doped EDFs for space-based optical communications, requiring robust radiation stability.

A Compact RF Energy Harvesting Wireless Sensor Node with an Energy Intensity Adaptive Management Algorithm.

This paper presents a compact RF energy harvesting wireless sensor node with the antenna, rectifier, energy management circuits, and load integrated on a single printed circuit board and a total size of 53 mm × 59.77 mm × 4.5 mm. By etching rectangular slots in the radiation patch, the antenna area is reduced by 13.9%. The antenna is tested to have an S11 of -24.9 dB at 2.437 GHz and a maximum gain of 4.8 dBi. The rectifier has a maximum RF-to-DC conversion efficiency of 52.53% at 7 dBm input energy. The proposed WSN can achieve self-powered operation at a distance of 13.4 m from the transmitter source. To enhance the conversion efficiency under different input energy densities, this paper establishes an energy model for two operating modes and proposes an energy-intensity adaptive management algorithm. The experiments demonstrated that the proposed WSN can effectively distinguish between the two operating modes based on input energy intensity and realize efficient energy management.