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13 pages, 713 KiB

Open AccessArticle

Design and Analysis of an O+E-Band Hybrid Optical Amplifier for CWDM Systems

by Benish Kanwal, Ammar Armghan, Salman Ghafoor, Ahmad Atieh, Muhammad Sajid, Tasleem Kausar, Jawad Mirza and Yun Lu

Micromachines 2022, 13(11), 1962; https://doi.org/10.3390/mi13111962 - 12 Nov 2022

Cited by 1 | Viewed by 1934

Abstract

Broadband amplification in the O+E-band is very desirable nowadays as a way of coping with increasing bandwidth demands. The main issue with doped fiber amplifiers working in this band such as the bismuth-doped fiber amplifier is that they are costly and not widely [...] Read more.

Broadband amplification in the O+E-band is very desirable nowadays as a way of coping with increasing bandwidth demands. The main issue with doped fiber amplifiers working in this band such as the bismuth-doped fiber amplifier is that they are costly and not widely available. Therefore, a wideband and flat-gain hybrid optical amplifier (HOA) covering the O+E-band based on a parallel combination of a praseodymium-doped fiber amplifier (PDFA) and a semiconductor optical amplifier (SOA) is proposed and demonstrated through numerical simulations. The praseodymium-doped fiber (PDF) core is pumped using a laser diode with a power of 500 mW that is centered at a wavelength of 1030 nm. The SOA is driven by an injection current of 60 mA. The performance of the HOA is analyzed by the optimization of various parameters such as the PDF length, Pr

^{3 +}

concentration, pump wavelength, and injection current. A flat average gain of 24 dB with a flatness of 1 dB and an output power of 9.6 dBm is observed over a wavelength range of 1270–1450 nm. The noise figure (NF) varies from a minimum of 4 dB to a maximum of 5.9 dB for a signal power of 0 dBm. A gain reduction of around 4 dB is observed for an O-band signal at a wavelength of 1290 nm by considering the up-conversion effect. The transmission performance of the designed HOA as a pre-amplifier is evaluated based on the bit-error rate (BER) analysis for a coarse wavelength-division multiplexing (CWDM) system of eight on-off keying (OOK)-modulated channels, each having a data rate of 10 Gbps. An error-free transmission over 60 km of standard single-mode fiber (SMF) is achieved for different data rates of 5 Gbps, 7.5 Gbps, and 10 Gbps. Full article

(This article belongs to the Special Issue Optical Sensing and Devices)

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13 pages, 560 KiB

Open AccessArticle

Performance Enhancement of Ytterbium-Doped Fiber Amplifier Employing a Dual-Stage In-Band Asymmetrical Pumping

by Jawad Mirza, Salman Ghafoor, Ammar Armghan, Osama I. Elhamrawy, Laiq Jamal, Musab Magam, Sharif Iqbal Mitu Sheikh and Khurram Karim Qureshi

Micromachines 2022, 13(9), 1488; https://doi.org/10.3390/mi13091488 - 7 Sep 2022

Cited by 1 | Viewed by 2072

Abstract

The performance of doped fiber amplifiers can be enhanced significantly with the help of multi-stage pumping technique provided that various critical parameters of pumps including their optical power and wavelength are optimized. We report the performance enhancement of a ytterbium doped fiber amplifier [...] Read more.

The performance of doped fiber amplifiers can be enhanced significantly with the help of multi-stage pumping technique provided that various critical parameters of pumps including their optical power and wavelength are optimized. We report the performance enhancement of a ytterbium doped fiber amplifier (YDFA) for a 1.02–1.08

μ

m spectral region with an optimized design based on a novel dual-stage in-band asymmetrical pumping scheme. By accurately adjusting the optical power and wavelength of pumps in both the stages, a record peak gain of around 62.5 dB and output power of 4.5 W are achieved for a signal wavelength of 1.0329

μ

m at an optimized length of Ytterbium-doped silica fiber and optimized doping concentration of Yb

^{3 +}

. Moreover, a minimum noise figure (NF) of 4 dB is observed for a signal wavelength of 1.0329

μ

m at the optimized parameters. Similarly, the effect of using high and low pump powers at the first and the second stage, respectively, on NF of the amplifier is also investigated at different values of signal powers. It is observed that the value of NF increases significantly by using high pump power at the first stage and low pump power at the second stage. Full article

(This article belongs to the Special Issue Optical Sensing and Devices)

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9 pages, 2713 KiB

Open AccessCommunication

Thrombin Determination Using Graphene Oxide Sensors with Co-Assisted Amplification

by Lei Liu, Qin Li, Haixia Shi and Li Gao

Micromachines 2022, 13(9), 1435; https://doi.org/10.3390/mi13091435 - 31 Aug 2022

Cited by 1 | Viewed by 1476

Abstract

Graphene oxide (GO) is widely used in sensors. The detection of proteins based on bare GO has been developed; however, the detection sensitivity needs to be improved. In this paper, a novel GO-DNA sensor for thrombin detection was developed using an aptamer linked [...] Read more.

Graphene oxide (GO) is widely used in sensors. The detection of proteins based on bare GO has been developed; however, the detection sensitivity needs to be improved. In this paper, a novel GO-DNA sensor for thrombin detection was developed using an aptamer linked to the surface of GO. Polyethylene glycol (PEG) was further used to prevent thrombin from nonspecific adsorption and to improve the sensitivity of the sensor for detection of thrombin. In order to improve the limit of detection for thrombin, we developed a GO and RecJf exonuclease co-assisted signal amplification strategy, and a detection limit of 24.35 fM for thrombin was achieved using this strategy. The results show that it is a promising method in analytical applications. Full article

(This article belongs to the Special Issue Optical Sensing and Devices)

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14 pages, 5752 KiB

Open AccessArticle

Design and Fabrication of a Tunable Optofluidic Microlens Driven by an Encircled Thermo-Pneumatic Actuator

by Wei Zhang, Heng Li, Yongchao Zou, Pengpeng Zhao and Zeren Li

Micromachines 2022, 13(8), 1189; https://doi.org/10.3390/mi13081189 - 28 Jul 2022

Cited by 5 | Viewed by 2042

Abstract

This paper presents the design, simulation, fabrication, assembly, and testing of a miniature thermo-pneumatic optofluidic lens. The device comprises two separate zones for air heating and fluid pressing on a flexible membrane. A buried three-dimensional spiral microchannel connects the two zones without pumps [...] Read more.

This paper presents the design, simulation, fabrication, assembly, and testing of a miniature thermo-pneumatic optofluidic lens. The device comprises two separate zones for air heating and fluid pressing on a flexible membrane. A buried three-dimensional spiral microchannel connects the two zones without pumps or valves. The three-dimensional microfluidic structure is realized using a high-resolution three-dimensional printing technique. Multi-physics finite element simulations are introduced to assess the optimized air chamber design and the low-temperature gradient of the optical liquid. The tunable lens can be operated using a direct-current power supply. The temperature change with time is measured using an infrared thermal imager. The focal length ranges from 5 to 23 mm under a maximum voltage of 6 V. Because of the small size and robust actuation scheme, the device can potentially be integrated into miniature micro-optics devices for the fine-tuning of focal lengths. Full article

(This article belongs to the Special Issue Optical Sensing and Devices)

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6 pages, 3629 KiB

Open AccessCommunication

High Sensitivity Fiber Interferometric Strain Sensors Based on Elongated Fiber Abrupt Tapers

by Haimiao Zhou, Ya-Pei Peng and Nan-Kuang Chen

Micromachines 2022, 13(7), 1015; https://doi.org/10.3390/mi13071015 - 27 Jun 2022

Viewed by 1351

Abstract

We demonstrate high-sensitivity fiber strain sensors based on an elongated abrupt taper. The fiber abrupt taper, with a tapered diameter ranging from 40–60 μm, was made by using a hydrogen microflame to break the waveguide adiabaticity so as to convert the fundamental mode [...] Read more.

We demonstrate high-sensitivity fiber strain sensors based on an elongated abrupt taper. The fiber abrupt taper, with a tapered diameter ranging from 40–60 μm, was made by using a hydrogen microflame to break the waveguide adiabaticity so as to convert the fundamental mode into cladding modes. The abrupt taper was further uniformly tapered by using a normal moving flame with a torch diameter of 7 mm to elongate the tapered region until the tapered diameter was down to 2.5–5 μm. The excited high-order modes were confined to propagate along the cladding and then recombined at the rear edge of the fiber taper to produce interferences with extinction ratios of up to 16 dB. The tapered region was pulled outwardly to change the optical path difference (OPD) between modes to measure the tensile strain with all the interfering wavelengths blue-shifted. The measured best strain sensitivity was 116.21 pm/με and the coefficient of determination R2 of linear fitting exhibits high linearity. This strain sensor based on elongated abrupt taper is several times higher than that of most of the fiber strain sensors ever reported. Full article

(This article belongs to the Special Issue Optical Sensing and Devices)

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10 pages, 4351 KiB

Open AccessArticle

THz Multi-Mode Q-Plate with a Fixed Rate of Change of the Optical Axis Using Form Birefringence

by Can Koral, Zahra Mazaheri and Antonello Andreone

Micromachines 2022, 13(5), 796; https://doi.org/10.3390/mi13050796 - 20 May 2022

Cited by 6 | Viewed by 2252

Abstract

We report the design, fabrication and experimental validation of a THz all-dielectric multi-mode q-plate having a fixed rate of change of the optical axis. The device consists of space-variant birefringent slabs manufactured by 3D printing using melt-extruded Acrylonitrile Butadiene Styrene (ABS). The desired [...] Read more.

We report the design, fabrication and experimental validation of a THz all-dielectric multi-mode q-plate having a fixed rate of change of the optical axis. The device consists of space-variant birefringent slabs manufactured by 3D printing using melt-extruded Acrylonitrile Butadiene Styrene (ABS). The desired form birefringence is analytically evaluated and experimentally measured by the THz time domain spectroscopy technique. The manufactured q-plate design is characterized using a polarization-sensitive imaging setup. The full electric field spatial maps are acquired from the beam propagating through the q-plate. The device enables the realization of both radial and azimuthal vector beams at discrete frequency intervals by controlling the space-dependent orientation of the ordinary and extraordinary axes in the transverse plane with a multi-mode sequence. Full article

(This article belongs to the Special Issue Optical Sensing and Devices)

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11 pages, 4035 KiB

Open AccessArticle

Design of a Highly Sensitive Photonic Crystal Fiber Sensor for Sulfuric Acid Detection

by Md. Ahasan Habib, Lway Faisal Abdulrazak, Musab Magam, Laiq Jamal and Khurram Karim Qureshi

Micromachines 2022, 13(5), 670; https://doi.org/10.3390/mi13050670 - 25 Apr 2022

Cited by 13 | Viewed by 2348

Abstract

In this research, a photonic crystal fiber (PCF)-based sulfuric acid detector is proposed and investigated to identify the exact concentration of sulfuric acid in a mixture with water. In order to calculate the sensing and propagation characteristics, a finite element method (FEM) based [...] Read more.

In this research, a photonic crystal fiber (PCF)-based sulfuric acid detector is proposed and investigated to identify the exact concentration of sulfuric acid in a mixture with water. In order to calculate the sensing and propagation characteristics, a finite element method (FEM) based on COMSOL Multiphysics software is employed. The extensive simulation results verified that the proposed optical detector could achieve an ultra-high sensitivity of around 97.8% at optimum structural and operating conditions. Furthermore, the proposed sensor exhibited negligible loss with suitable numerical aperture and single-mode propagation at fixed operating conditions. In addition, the circular air holes in the core and cladding reduce fabrication complexity and can be easily produced using the current technology. Therefore, we strongly believe that the proposed detector will soon find its use in numerous industrial applications. Full article

(This article belongs to the Special Issue Optical Sensing and Devices)

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11 pages, 2960 KiB

Open AccessArticle

Optical Fiber–Based Continuous Liquid Level Sensor Based on Rayleigh Backscattering

by Xingqiang Chi, Xiangjun Wang and Xuan Ke

Micromachines 2022, 13(4), 633; https://doi.org/10.3390/mi13040633 - 17 Apr 2022

Cited by 5 | Viewed by 3587

Abstract

This work reports an optical fiber–based continuous liquid level sensor for cryogenic propellant mass gauging, which has significant advantages over the existing liquid level sensors in terms of accuracy, simplicity, and reliability. Based on Rayleigh backscattering coherent optical frequency domain reflectometry, every point [...] Read more.

This work reports an optical fiber–based continuous liquid level sensor for cryogenic propellant mass gauging, which has significant advantages over the existing liquid level sensors in terms of accuracy, simplicity, and reliability. Based on Rayleigh backscattering coherent optical frequency domain reflectometry, every point of the sensing fiber is a liquid sensor which is able to distinguish liquid and vapor. We obtained a measurement accuracy of 1 mm for the optical fiber sensor by measuring both liquid nitrogen and water levels. For the first time, for practical applications, we experimentally studied the influence of ambient temperature and strain changes on the sensing performance as well as the repeatability of the optical fiber–based liquid level sensor’s measurements. Full article

(This article belongs to the Special Issue Optical Sensing and Devices)

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9 pages, 4566 KiB

Open AccessCommunication

High Sensitivity Strain Sensors Using Four-Core Fibers through a Corner-Core Excitation

by Lina Suo, Ya-Pei Peng, Cheng-Kai Yao, Shijie Ren, Xinhe Lu and Nan-Kuang Chen

Micromachines 2022, 13(3), 431; https://doi.org/10.3390/mi13030431 - 11 Mar 2022

Cited by 5 | Viewed by 2133

Abstract

A weakly-coupled multicore fiber can generate supermodes when the multi-cores are closer to enter the evanescent power coupling region. The high sensitivity strain sensors using tapered four-core fibers (FCFs) were demonstrated. The fan-in and fan-out couplers were used to carry out light coupling [...] Read more.

A weakly-coupled multicore fiber can generate supermodes when the multi-cores are closer to enter the evanescent power coupling region. The high sensitivity strain sensors using tapered four-core fibers (FCFs) were demonstrated. The fan-in and fan-out couplers were used to carry out light coupling between singlemode fibers and the individual core of the FCFs. A broadband lightsource from superlumminescent diodes (SLDs) was launched into one of the four cores arranged in a rectangular configuration. When the FCF was substantially tapered, the asymmetric supermodes were produced to generate interferences through this corner-core excitation scheme. During tapering, the supermodes were excited based on a tri-core structure initially and then transited to a rectangular quadruple-core structure gradually to reach the sensitivity of 185.18 pm/μԑ under a tapered diameter of 3 μm. The asymmetric evanescent wave distribution due to the corner-core excitation scheme is helpful to increase the optical path difference (OPD) between supermodes for improving the strain sensitivity. Full article

(This article belongs to the Special Issue Optical Sensing and Devices)

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Review

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21 pages, 5521 KiB

Open AccessReview

Six-Degree-of-Freedom Posture Measurement Technologies Using Position Sensitive Detectors (PSDs): State of the Art

by Xiangxu Meng, Siwei Sun, Xuetao Yan, Fengman Liu, Liqiang Cao, Qidong Wang and Yu Sun

Micromachines 2022, 13(11), 1903; https://doi.org/10.3390/mi13111903 - 3 Nov 2022

Cited by 6 | Viewed by 2332

Abstract

Six degree-of-freedom (6-DOF) posture measurement is an important academic research topic which has been broadly applied in many fields. As a high-speed photoelectronic sensor with ultra-high resolution and precision, position sensitive detector (PSD) has shown to be one of the most competitive candidates [...] Read more.

Six degree-of-freedom (6-DOF) posture measurement is an important academic research topic which has been broadly applied in many fields. As a high-speed photoelectronic sensor with ultra-high resolution and precision, position sensitive detector (PSD) has shown to be one of the most competitive candidates in 6-DOF measurement. This review presents the research progress of PSD-based 6-DOF posture measurement systems in the field of large-scale equipment assembly, ultra-precision manufacturing and other emerging areas. A total of six methods for implementing 6-DOF measurement are summarized and their advantages and limitations are discussed. Meanwhile, the paper illustrates challenges, potential solutions and future development trends. Full article

(This article belongs to the Special Issue Optical Sensing and Devices)

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