Compact Fiber Research Articles

Comprehensive Evaluation of Nutritional, Physicochemical, and Volatile Profiles of Selected Bovine Head Muscles

This study analyzed the nutritional composition, physicochemical properties, and volatile profiles of three major bovine head muscles—medial pterygoid, masseter, and buccinator—to reduce byproduct resource waste and increase the utilization rate of bovine head to establish a foundation for its industrial use. Compared to tenderloin, which is popular among consumers, these head muscles were found to be rich in collagen (4.90–13.1 mg/g), low in fat (0.39–1.61%), and abundant in free amino acids (143.93–223.00 mg/100 g). Their compact fiber structures, with minimal gaps between myocytes, resulted in lower cooking and press losses, making them suitable for various production processes. Notably, the medial pterygoid and masseter muscles contained high levels of polyunsaturated fatty acids (PUFAs) and lower saturated fatty acids (SFAs), with a PUFA/SFA ratio exceeding 0.45. The buccinator muscle, while containing more volatile organic compounds associated with undesirable odors and bitter amino acids, was not indicative of spoilage. Overall, this study confirmed that bovine head muscles possess high collagen, low fat, and diverse nutritional qualities, making them suitable as premium raw materials for value-added meat products, and their returns will be most economically equal to the meat derived from cattle.

Compact Si-SiN photonic fiber optic gyroscope transceiver for large volume manufacturing

Miniaturized interferometric fiber optic gyroscopes (IFOGs) providing high-precision angular measurement are highly desired in various smart applications. In this work, we present a high-performance Si-SiN photonic FOG transceiver composed of an optical source, polarizer, splitter, and on-chip germanium (Ge) photodetector (PD). The transceiver is assembled in a standard butterfly package with a thermo-electric cooler (TEC). The optical loss (including two edge couplers, as well as one 3 dB splitter) and polarization extinction ratio (PER) are less than 7 dB and greater than 20 dB at room temperature, respectively. Built with the polarization maintaining (PM) fiber coil with 70 mm average diameter and 580 m length, the transceiver-based IFOG exhibits record-low bias stability of 0.022 deg/h at an integration time of 10 s, the angular random walk (ARW) of 0.0012 deg/h, and the bias instability of 0.003 deg/h, to the best of our knowledge. The preliminary reliability test agrees well with the practical requirements. Our work verifies that the on-chip Ge PD is eligible for high-performance FOG applications. Leveraged with the typical CMOS compatible 8-inch (200 mm diameter wafers) silicon photonics platform and decreased fiber splicing points, the presented transceiver provides a promising solution toward a low-loss and miniaturized FOG system with large volume manufacturing capability.

Probe-type optical fiber sensors for electric field distribution measurement

This paper reports a compact fiber optical electric field (E-field) sensor aiming for the precise detection of transient E-field distributions. Here, a reflective polarization-reciprocal optical path is proposed, which inherently mitigates the temperature-induced birefringence interference of the electro-optical crystal without the need for additional optical elements, thereby facilitating a reduced-size sensing probe. Furthermore, an adaptive particle swarm optimization (A-PSO) algorithm has been utilized for the first time to optimize the insulation structure of the optical E-field sensor, which significantly suppresses field distortion within the sensing region by 50%. This method addresses the technical gap in optical E-field sensor structure optimization, providing an effective means to improve its spatial resolution. The experimental results demonstrate that the proposed sensor exhibits a broad response frequency range from 50 Hz to 15 MHz, with a sensitivity of 0.675 V/kV cm−1. The proposed sensor successfully monitors the spatial distribution of electric fields in the lightning interception region of a lightning rod, thereby validating its effectiveness.

Silicon‐Nitride‐Integrated Hybrid Optical Fibers: A New Platform for Functional Photonics

AbstractHybrid optical fibers that integrate exotic materials within more traditional silica glass architectures open a route for the development of highly functional all‐fiber photonic systems. Here, a compact hybrid optical fiber platform is reported formed by depositing a silicon nitride (SiNx ‐ nitride‐rich) nanolayer onto the surface of fused‐silica microfibers via plasma‐enhanced chemical vapor deposition. The SiNx thickness can be precisely tuned over a range of tens of nanometers, while maintaining an ultra‐smooth deposition surface, allowing for tunable coupling between the modes guided predominantly in the nanolayer and the fiber core. The effective indices of the hybrid modes display an anti‐crossing behavior under resonant conditions, resulting in a rich dispersion landscape that can be tailored via adjusting the SiNx thickness. By fabricating a SiNx‐silica hybrid microfiber with precise dispersion engineering and a low insertion loss, a flat supercontinuum spectrum spanning >1.5 octaves (−20 dB level) has been generated. The results demonstrate that SiNx‐silica hybrid microfibers can offer a unique combination of broadband transmission and wide tunablity of the mode properties, while still retaining the benefits of robust integration with conventional silica glass fiber networks, providing a rich playground for hybrid fiber‐based photonic systems.

A curvature and temperature simultaneous measurement sensor based on micro-taper Formed MZI and an Embedded FBG

Abstract A compact fiber Bragg grating (FBG) and Mach–Zehnder interferometer (MZI) compound for simultaneous measurement of bending and temperature is described. The FBG and MZI are fabricated in fiber forming a compact device, which is different from the previously developed axial cascade of different structures. Experimental results show that the FBG and MZI have different sensitivities for bending and temperature, allowing this device to measure bending and temperature simultaneously. The device has the advantages of small size, simple preparation steps, low cost, short preparation cycle, etc. Due to its excellent performance, it has the potential to become an excellent universal bending and temperature sensor.

High-power pulsed Raman fiber laser with wavelength over 2.4 μm

In this paper, the compact high-power pulsed Raman fiber lasers based on single-pass stimulated Raman scattering have been experimentally presented. Home-built noise-like pulse laser centered at ∼1994.7 nm with an envelope width of ∼20.8 ns was utilized as the pump laser, which can provide a maximal output power of ∼19.1 W without a notable spectral broadening. The 1st-order Raman laser operated at ∼2190.8 nm with a maximal output power of ∼4.11 W and a spectral purity of ∼93 % was achieved. Furthermore, by finely optimizing the length of Raman-gain fiber, the 2nd-order Raman laser centered at ∼2408.5 nm with a maximal power of ∼2.36 W was achieved, which represents the maximal value of Raman laser at 2.4 μm in silica-core fiber, to the best of our knowledge. The high-power pulsed Raman fiber lasers may have the potential applications in polymer material processing and spectroscopy.

Ultrafast and Reproducible Fiber-Optic Hydrogen Sensor via a Tilted Fiber Grating With Pd/WO3 Nanocoating

Hydrogen, a high-density and clean energy, has been widely used in various critical applications. However, the safety risk caused by hydrogen leakage during storage and transportation is still a non-negligible issue. Therefore, it is necessary to offer hydrogen sensors with fast response and high repeatability, and it will be perfect for achieving in situ monitoring over the lifecycle of hydrogen production and utilization. Here, we propose a compact optical fiber sensor with a short section of the tilted Bragg fiber grating (TFBG) inscribed in the fiber core and a palladium and tungsten trioxide (Pd/WO3) combined film of 40 nm thickness over the fiber surface. The TFBG excites tens of narrow cladding resonances, part of which possess refractive indexes matching that of the Pd/WO3 coating and providing the high sensitivity to the surrounding hydrogen concentration change. The sensor offers improved sensing characteristics, including the fast response time (less than 10 s), high repeatability (over tens of measurement), and excellent linear response (higher than 99.6%) over the 0% to 3% concentration range.

Compact Three-Channel Photonic Crystal Fiber Sensor Based on Surface Plasmon Resonance

Compact Three-Channel Photonic Crystal Fiber Sensor Based on Surface Plasmon Resonance

Enhanced axial strain and vector magnetic field sensitivity in MZI utilizing dual cascaded air bubbles with tapered fiber.

In this study, we believe this is a novel and compact fiber optic sensor for measuring strain and vector magnetic fields that has been proposed and examined. The sensor is comprised of a sequence of two bubbles and a tapered fiber with a diameter of 31µm, offering a maximum strain sensitivity of -44.5 pm/µɛ. A susceptible magnetic field sensing structure can be achieved by simply bonding the strain device to a magnetostrictive material. Results demonstrate that the sensor exhibits a magnetic field sensitivity of -0.7838 nm/mT, with a linear fit of 0.9931 within the 8 to 28 mT. The direction sensitivity is calculated to be 230.85 pm/° for a magnetic field of 24 mT. This work demonstrates the device's great mechanical strength, low cross-sensitivity to temperature, ease of manufacture, and versatility in measuring strain and vector magnetic fields, making it suitable for use in civil engineering, aerospace, and other industrial fields.

Multi-Degree-of-Freedom Force Sensor Incorporated into Soft Robotic Gripper for Improved Grasping Stability.

In recent years, soft robotic grippers have emerged as a promising solution for versatile and safe manipulation of objects in various fields. However, precise force control is critical, especially when handling delicate or fragile objects, to avoid excessive grip force application or to prevent object slippage. Herein, we propose a novel three-degree-of-freedom force sensor incorporated within a soft robotic gripper to realize stable grasping with force feedback. The proposed optical sensor employs lightweight and compact optical fibers, thereby allowing for cost-effective fabrication, and a robust sensing system that is immune to electromagnetic fields. By innervating the soft gripper with optical fibers, a durable system is achieved with the fibers functioning as a strengthening layer, thereby eliminating the need for embedding an external stiffening structure for efficient bending actuation. The innovative contact-based light loss sensing mechanism allows for a robust and stable sensing mechanism with low drift (<0.1% over 9000 cycles) that can be applied to soft pneumatic bending grippers. We used the developed sensor-incorporated soft gripper to grasp various objects, including magnetic materials, and achieved slip detection along with grip force feedback without any signal interference. Overall, this study proposes a robust measuring multi-degree-of-freedom force sensor that can be incorporated into grippers for improved grasping stability.

Generation of high-energy self-mode-locked pulses in a Tm-doped fiber laser

The incorporation of a material-based or artificial saturable absorber into a fiber laser cavity imposes a limitation on energy enhancement owing to its low damage threshold and high environmental sensitivity. To address this issue, one promising alternative approach is the utilization of the self-mode-locking technique. Here, we present a robust self-mode-locked Tm-doped fiber laser with high pulse energy emission. A simple and compact fiber laser structure is realized by utilizing a section of a Tm-doped fiber, serving both as a gain medium and a saturable absorber. Thus, the operational stability is enhanced, especially under high-energy conditions. Furthermore, the realization of high-energy pulses is accomplished through the integration of dispersion management technique. Experimental results reveal that the maximum single-pulse energy increases from 34.8 pJ to 120.2 nJ as the round-trip group delay dispersion decreases from −0.43 to −12.40 ps2. The proposed self-mode-locked Tm-doped fiber laser under high-energy operation exhibits remarkable performance. Our results provide a simple approach to obtaining a mid-infrared laser source with high pulse energy and hold significant potential for advancing high-energy laser systems.

Tunable and switchable multi-wavelength mode-locked fiber lasers induced by an optimized hybrid mode-locked composite filtering effect.

A multi-wavelength mode-locked fiber laser can generate different wavelengths from a single laser cavity, offering potential as a dual-frequency comb and serving as an ideal light source for terahertz wave generation. We present an optimized hybrid mode-locked Er-doped fiber laser with flexible outputs: switchable and tunable dual-wavelength mode-locking, along with stable tri-wavelength mode-locking, which is achieved by introducing 0.69 m polarization-maintaining fiber and bent 200 m single-mode fiber to enhance intra-cavity birefringence and nonlinear effect to optimize the hybrid mode-locking effect, that is, build the composite filter effect. The dual-wavelength mode-locking not only covers a tunable wavelength range of 5 nm but also provides tunable wavelength intervals of 4-26 nm due to the composite filter effect. The formation dynamics of the tri-wavelength mode-locking can be switched either pair-by-pair or one-by-one. This approach enables the realization of wavelength interval tunable dual-wavelength mode-locking in mode-locked fiber lasers simply by introducing fiber without additional actions. Such a simple, compact fiber laser with tunable wavelength capabilities holds significant potential for diverse applications.

Tunable mode-locked holmium-doped fiber laser based on GIMF-SIMF-GIMF structure at 2.09 µm

In this study, a structure of graded-index multimode fiber-step index multimode fiber-graded index multimode fiber (GIMF-SIMF-GIMF) was used as a saturable absorber (SA) to generate mode-locking in a holmium-doped fiber laser (HDFL). The HDFL was pumped with a compact in-house thulium-doped fiber laser (TDFL) operating at 1943 nm with a maximum output power of 2.1 W. Mode-locked pulses with a pulse duration of 1.61 ps were successfully generated at the center wavelength of 2091.1 nm. The pulse had a repetition rate of 12.79 MHz with a bit of fluctuation of 2.09 %, indicating stable pulses. The mode-locked pulses were also tunable with a range from 2086.5 nm to 2091.1 nm by stretching the GIMF part of the SA. This first report demonstrated mode-locking using nonlinear multimode interference (NL-MMI) using GIMF-SIMF-GIMF structure as a saturable absorber in HDFL operating near 2.1 µm wavelength.

Fiber optic strain sensor based on enhanced harmonic Vernier effect

In sensors utilizing the traditional harmonic Vernier effect, it is imperative to isolate the reference interferometer to mitigate the impact of external environmental fluctuations on the reference spectrum, thereby averting measurement inaccuracies. However, achieving such isolation between interferometers in compact fiber optic sensors poses significant challenges. We propose a fiber optic strain sensor based on the enhanced harmonic Vernier effect. In the enhanced harmonic Vernier effect, two interferometers are simultaneously involved in sensing. Hence, the isolation of interferometers is no longer a concern. Furthermore, the two interferometers exhibit responses with opposite signs, leading to a greater displacement of the envelope. Consequently, the sensitivity of the sensor is further enhanced without altering the harmonic order. Firstly, we conducted numerical simulations to analyze the enhanced harmonic Vernier effect. Secondly, we fabricated a Fabry–Perot interferometer (FPI) and a Mach–Zehnder interferometer (MZI) with strain sensitivity of opposite signs, generating a first-order harmonic. The experimental results indicate that the sensor’s sensitivity is 15.1 pm/μϵ, which is 1.41 and 2.80 times higher than the traditional harmonic Vernier effect using FPI and MZI as sensing interferometers, respectively. The proposed sensor and enhancement method hold promising potential for applications in high-sensitivity measurement fields.

High-performance optical fiber differential urea sensing system for trace urea concentration detection with enhanced sensitivity using liquid crystals

A compact optical fiber differential sensing system consisting of microfiber interferometer (MFI) functionalized urease combined with stearic acid (SA)-doped 4-cyano-4′-pentylbiphenyl (5CB) and two fiber Bragg gratings (FBGs) for urea detection has been proposed and experimentally demonstrated. The SA-doped 5CB plays an important role of sensing signal amplification in urease specific recognition of urea. The hydrolysis reaction between urea and urease at the microfiber surface causes the deprotonation and self-assembly of SA, which further induces the reorientation of 5CB from planar alignment to homeotropic alignment. This process can be captured and transduced into the macroscopic wavelength shift of the MFI and power difference of two FBGs in the differential sensing system. The experimental results show that the differential sensing system can effectively detect urea in artificial urine, where the sensitivity of MFI is 3.85 nm/mM with a detection limit of 0.03 mM and the power difference sensitivity of two FBGs is 15.05 dB/mM with a detection limit of 0.01 mM within low concentration range of 0.01–0.1 mM. Furthermore, the differential sensing system has good selectivity, affordability, and temperature self-compensation. Therefore, the differential sensing system can be used as a sensitive method for urea detection and has potential applications in human health detection.

GHz-rate 57-fs acousto-optic mode-locking fiber laser based on cascaded all-fiber pulse compression.

We demonstrate a compact ultrafast fiber laser system that can deliver 1.87 GHz pulse train at 1550 nm with a pulse energy of 52 pJ and an ultrashort pulse duration of 57 fs. While an acousto-optic mode-locking fiber laser was used as the seed light source at GHz rate, a stage of Er-doped fiber amplifier boosted the laser power to ∼320 mW, giving a pulse energy of ∼170 pJ. Then, a pulse compression setup was constructed, providing a high compression ratio of ∼10 with a total efficiency of ∼32%. In the cascaded compression configuration, multiple fiber samples with alternately normal and anomalous dispersion were fused together, providing efficient nonlinear spectral broadening while suppressing excessive pulse broadening over propagation. This GHz-rate ultrafast fiber laser, with compact configuration, broad optical spectrum, and high time-resolving ability could be used as the seed light source for constructing high-rate, high-power ultrafast laser systems and may find a few applications in optical measurements and microwave photonics.

Design and simulation of a compact plasmonic photonic crystal fiber filter with wide band and high extinction ratio

In order to realize the performance optimization and function expansion of modern all-optical systems, this work presents a compact plasmonic photonic crystal fiber (PCF) filter, using finite element tool. The deposited gold and graphene layers within the elliptical pores interact with the transmitted light, creating surface plasmon resonance (SPR) effect that amplifies the energy difference between x- and y-polarized light greatly. The simulation results indicate that the structural parameters are configured with the cladding holes' diameter of 0.6 μm, the large-holes’ diameter of 1.2 μm, the inner small-holes’ diameter of 0.2 μm, the lattice constant of 2.0 μm, the elliptical holes' minor axis length of 0.45 μm, the elliptical holes' major axis length of 1.30 μm, the gold layer thickness of 50 nm, and the graphene layer thickness of 20 nm, the central wavelength of the proposed PCF filter is 1.56 μm. When the length of this PCF filter is 1 mm, a maximum extinction ratio (ER) of 133 dB, an operating bandwidth exceeding 800 nm, covering two common communication windows of 1.31 μm and 1.55 μm, as well as a low insertion loss (IL) of 0.59 dB can be achieved. What's more, the feasibility of fabricating the device is also examined. This filter with compactness, broadband and high-extinction demonstrates promising applications in optical communication, optical sensing, optical computing, and various other fields.

A Novel Compact High-Sensitivity Fiber Bragg Grating Sensor for Microvibration Measurement of Robot Joints

A Novel Compact High-Sensitivity Fiber Bragg Grating Sensor for Microvibration Measurement of Robot Joints

Compact and efficient high-power mid-infrared supercontinuum fiber laser source based on a noise-like pulse and germania fiber

Here, we demonstrate a compact and efficient high-power mid-infrared supercontinuum (MIR-SC) laser source based on a tunable noise-like pulse (NLP) fiber laser system and a short section of single-mode germania-core fiber (GCF). The NLP all-polarization-maintaining fiber laser system can deliver the maximum output power of ∼30.6 W and a broadband spectrum (∼1.8-2.7 µm) with a compact single-stage fiber amplifier. By directly pumping only ∼6.5 cm-long GCF with a core diameter of ∼3.5 µm, a MIR-SC (spectral coverage of ∼1.5-3.3 µm) with a maximum power of ∼25.2 W and a power conversion efficiency ∼81.2% is obtained, which represent the highest power and efficiency in any single-mode GCF-based MIR-SCs, to the best of our knowledge. Our study contributes to the high-power MIR-SC laser source with compact all-fiber configuration, and will prompt its practical applications.

Larval biomass production from the co-digestion of mushroom root waste and soybean curd residues by black soldier fly larvae (Hermetia illucens L.).

People are increasingly using black soldier fly larvae (BSFL) as a sustainable waste management solution. They are high in protein and other essential nutrients, making them an ideal food source for livestock, poultry, and fish. Prior laboratory studies with BSFL developed on pure mushroom root waste (MRW) showed poor conversion efficiency compared to a regular artificial diet. Therefore, we mixed the nutrient-rich soybean curd residues (SCR) with MRW in different ratios (M2-M5). Pure mushroom root waste (M1, MRW 100%) had the lowest survival rate (86.2%), but it increased up to 96.9% with the SCR percentage increasing. M1 had the longest developmental period (31.1days) and the lowest BSFL weight (7.4g). However, the addition of SCR reduced the development time to 22.0 and 21.5days in M4 (MRW 40%, SCR 60%) and M5 (MRW 20%, SCR 80%), respectively, and improved the larval weight to 10.9g in M4 and 11.8g in M5. Other groups did not have as much feed conversion ratio (FCR) (8.4 for M4 and M5), bioconversion (M4 5.4%; M5 5.9%), or lipid content (M4 25.2%; M5 24.3%). These mixtures did.Compare this to M1. We observed better results, with no significant differences between the M4 and M5 groups and their parameters. In the present study, our main target was to utilize more MRW. Therefore, we preferred the M4 group in our nutritional and safety investigation and further compared it with the artificial diet (M7). The heavy metals and essential amino acids (histidine 3.6%, methionine 2.7%, and threonine 3.8%) required for human consumption compared to WHO/FAO levels showed satisfactory levels. Furthermore, fatty acids (capric acid 1.9%, palmitic acid 15.3%, oleic acid 17.3%, and arachidonic acid 0.3%) also showed higher levels in M4 than M7. The SEM images and FT-IR spectra from the residues showed that the BSFL in group M4 changed the structure of the compact fiber to crack and remove fibers, which made the co-conversion mixture better.