Fiber Ferrule Research Articles

On the Synthesis of Graphene Oxide/Titanium Dioxide (GO/TiO2) Nanorods and Their Application as Saturable Absorbers for Passive Q-Switched Fiber Lasers.

We report passively Q-switched pulse operation through an erbium-doped fiber laser (EDFL) utilizing graphene oxide/titania (GO/TiO2) nanorods as a saturable absorber. The GO/TiO2 nanorods were fabricated using a Sol-gel-assisted hydrothermal method. The optical and physical characterization of the GO/TiO2 was then characterized using a field-emission-scanning electron microscope (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and diffuses reflectance spectroscopy (DRS). To investigate the performance of the Q-switched EDFL based on the GO/TiO2 SA, the prepared nanorods were mechanically deposited on the fiber ferrule employing adhesion effects of in-dex-matching gel. This integration of the nanorod SA resulted in a self-starting Q-switching opera-tion initiated at a pump power of 17.5 mW and sustained up to 306.9 mW. When the pump range was tuned from 17.5 to 306.9 mW, the emission wavelength varied from 1564.2 to 1562.9 nm, pulse repetition rates increased from 13.87 kHz to 83.33 kHz, and pulse width decreased from 30.27 µs to 3.75 µs. Moreover, at the maximum pump power of 306.9 mW, the laser exhibited an average output power of 0.74 mW, a peak power of 1.54 mW, and a pulse energy of 8.88 nJ. Furthermore, this study investigates the GO/TiO2 damage threshold and prolonged stability of the proposed EDFL system.

Comparing optical deposition and drop casting for enhanced tunability in Q-switched fiber lasers using a biogenic AgNPs-CS saturable absorber

This study presents the successful synthesis and characterization of silver nanoparticles (AgNPs) using Camellia sinensis (CS) leaf extract as a biogenic saturable absorber (SA) for tunable Q-switched applications. The AgNPs-CS SA was fabricated through optical deposition and drop casting methods into a fiber ferrule. The nonlinear optical properties of AgNPs-CS as SA were investigated, revealing a modulation depth of 24.37% and a saturation intensity of 0.15 MW cm−2. Q-switching based on optical deposition exhibited a pump power of 213.40 mW, a 3-dB bandwidth of 3.20 nm, a pulse repetition rate of 78.74 kHz, and a pulse duration of 2.38 μs. Meanwhile, the drop casting method showed a 3-dB bandwidth of 2.0 nm, a pulse repetition rate of 53.05 kHz, and a pulse duration of 5.53 μs for the Q-switched pulse. Additionally, the tunability of wavelength in Q-switching using AgNPs-CS SA was investigated. The drop casting method achieved a tuning range of 32.00 nm, covering the S-band to C-band, while the optical deposition technique resulted in a tuning range of 54.20 nm, spanning from the C-band to L-band. Notably, this work represents the first utilization of AgNPs synthesized with leaf extract as a biogenic SA in the tunability of Q-switched lasers, employing two distinct fabrication techniques for the SA.

Q-switched triple-wavelength erbium-doped fiber laser with black phosphorus absorber

We achieved a notable advance in laser technology by generating a triple-wavelength output in a Q-switched Erbium-doped fiber laser (EDFL) using a new black phosphorous saturable absorber (BPSA). The BPSA was made by exfoliating multilayer BP material from a bulk crystal and transferring it onto a fiber ferrule tip. Upon integration into an EDFL ring cavity, this BPSA facilitated the production of Q-switched pulses at wavelengths of 1530.4, 1531.5, and 1532.6 nm. This distinctive triple-wavelength lasing phenomenon, characterized by uniform spacing, arises from standing wave interference within the ring cavity, leveraging the highly nonlinear active gain medium. With an increase in pumping strength from 147 mW to 223 mW, the repetition rate escalated from 41.15 to 60.83 kHz, accompanied by a reduction in pulse width from 8.45 µs to 6.06 µs. Notably, the highest recorded pulse energy peaked at 11.8 nJ. These findings highlight the efficacy of BP as a Q-switcher for the generation of multi-wavelength pulses, marking a significant advancement in laser technology.

Spider silk biological material for Q-switched temperature sensor

Abstract A temperature sensor using compact design and highly sensitivity of side polished fiber and fiber Bragg grating as the sensing elements, Q-switched pulse fiber laser source with spider silk as a saturable absorber is proposed and demonstrated. Spider silk sample was gently collected from a live spider, specifically, the jumping spider of Plexippus sp. which then incorporated within the laser cavity by deposited the silk onto the surface of the fiber ferrule to facilitate the generation of Q-switched pulse fiber laser. The temperature variations were detected by monitoring the pulse train and radio frequency shift from the oscilloscope. The performance of the side polished fiber sensor probe shows a sensitivity of 0.1522 kHz/°C, with 0.9479 coefficient of determination value as the temperature increased from -0.5 °C to +3.1 °C. Besides, a linear temperature re-sponse in the range of 25 °C – 55 °C with a sensitivity of 0.0423 kHz/°C, and a linear correlation coefficient of 0.951 was experimentally achieved for a fiber Bragg grating device. The spider silk as a saturable absorber material is compatible with fiber optic interconnection and the temperature sensing characteristics were successfully demonstrated. The sensor's straight-forward design further enhances its desirability as a sensor for temperature monitoring, including in the field of biological treatments, consumer electronics, detection of chemical analytes, and medical diagnosis.

Biological material spider silk by direct incorporation onto fiber ferrule for wavelength tunable Q-switched application

This study presents a novel structure saturable absorber (SSA) based on spider silk for wavelength tunable Q-switched erbium-doped fiber laser (EDFL) operation from S to L bands. The nonlinear optical absorption of spider silk was measured, showing a high modulation depth of 64.92%, a low saturation intensity of 0.03 MW cm−2, and a non-saturable loss of 24%. By adjusting the polarization controller, a wavelength tunable Q-switched EDFL was achieved, with a tuning range of 64 nm from 1522 nm to 1586 nm. The Q-switched pulses had a repetition rate varying from 20.62 kHz to 6.57 kHz and a pulse width ranging from 14.02 μs to 26.30 μs, corresponding to an output power from −11.31 dBm to −9.02 dBm at the maximum pump power of 151.40 mW. The proposed SSA using spider silk offers a low-cost, eco-friendly, and high-performance solution for wide wavelength tunable Q-switched EDFL applications in optical testing, fiber communication, optical fiber sensing, and ultrafast lasers.

Passively Q-switched Er-doped fiber laser based on carbon-doped silver nanoparticles saturable absorber prepared using laser ablation method

In this work, we investigate the effect of carbon-doped silver nanoparticles on the Q-switched performance of erbium-doped fiber laser (EDFL). The carbon-doped silver nanoparticles were synthesized using a laser ablation method. The prepared nanoparticles were inserted between fiber ferrules using the adhesion process of the index-matched gel. Incorporating a saturable absorber inside the laser cavity initiates a stable Q-switched mechanism at 11.2 mW of threshold power. The measured results demonstrate that as the pump power of EDFL increases from 11.2 to 267 mW, the pulse repetition, and pulse width tuned from 21.33 to 95.2 kHz and 13.3–3.18 µs, respectively. At 267 mW of pump, the maximum average output power, pulse energy, and peak power were further measured to be 2.36 mW, 24.68 nJ, and 7.76 mW, respectively. Besides, the stability and threshold characteristics of EDFL based on carbon-doped silver nanoparticles were further explored. This study shows that the synthesis of metal nanoparticles using the laser ablation technique and their implementation as saturable absorber represents a promising avenue for advancing ultrafast laser technologies with improved stablility, efficiency, and tunability.

Fe-MOF as a novel saturable-absorber for pulse operation in erbium-doped fiber lasers

This study demonstrated the utilization of an iron metal–organic framework (Fe-MOF) thin film to act as a saturable absorber in a passively Q-switched erbium-doped fiber laser cavity. The Fe-MOF thin film was prepared using the conventional solution method technique and was characterized using XRD, SEM, EDX, and Raman. The integration of Fe-MOF thin film into fiber ferrule yields a stable self-starting Q-switching operation at a pump power of 55.4 mW. Besides at a maximum pump power of 531 mW, emission at 1561.8 nm, minimum pulse duration of 3.9 µs, maximum repetition rate of 91.7 kHz, and a maximum average output power of 10.8 mW was achieved. The measured results further reveal a maximum 53 dB single-to-noise ratio (SNR), signifying good pulse stability. Moreover, we examined a Fe-MOF-SA damage threshold and long-term stability. The optimum stability, excellent threshold, and shorter pulse width highlight the potential of Fe-MOF as a promising saturable absorber (SA) in a passively Q-switched fiber laser. In addition, this study broadened the applications of MOFs in pulse laser technology and introduced a new approach to advancing the field of ultrafast photonics.

Inorganic Material of Magnesium Nitrate Mg(NO3)2 Film as Q-Switcher in the C-Band Region

A novel inorganic material of Magnesium Nitrate (Mg(NO3)2) thin film is successfully investigated in the C-band region. The Q-switcher is Mg(NO3)2 thin film. The solvent casting method has been applied to prepare Mg(NO3)2 thin film before being positioned within the fiber ferrule duo to act as a Q-switcher. Thereby, the modulation depth and the saturation intensity of the Mg(NO3)2 thin film exhibit at 32.40% and 0.07 MW/cm2, respectively. It is possible to produce a steady Q-switched pulse fiber laser with a maximum pump power of 403.00 mW, a repetition rate of 72.56 kHz, and a pulse width of 3.00 µs. In addition, the tunable Q-switched pulse fiber laser is also examined using a figure-of-eight cavity design incorporating a tunable bandpass filter (TBF). Consequently, the operating wavelength is changed in the range of 1528 nm to 1552 nm, even while the pump power remains the same at 403.00 mW. During this time, the pulse width and repetition rate shifted from 2.10 µs to 4.10 µs and altered from 67.90 kHz to 35.80 kHz, respectively. Consequently, the Mg(NO3)2 thin film has the opportunity to be an effective saturable absorber for generating pulsed fiber lasers and can be applied in optical communications applications.

10 Hz Stable Mode-locked Er-Fiber Laser

Abstract: In this paper, a stable output at the reduction repetition rate from 80 MHz mode-locked Er-doped fiber laser (EDFL) was demonstrated by adjusting the operating point for external LiNbO3 Mach-Zehnder‎ electro-optic intensity modulator to suppress harmonic mode-locked pulses. More than 70% of the laser beam was launched into the external pigtail Mach-Zehnder intensity modulator using single mode fiber with collimating lens and fiber (ferrule connector) FC adapter. The optimum values of Mach-Zehnder modulator bias voltages V0 and Vπ (half wave voltage) which resulted in maximum and minimum laser output power to leave the modulator were found at 6.5 and 0.29 V, respectively. The best modulation was achieved for the RF modulating signal with an opening time of about 8 ns. For driving voltage equal to Vπ, a clean mode-locked pulse train was generated with a pulse shape and energy similar to the input pulse, albeit with a low repetition rate. The minimum repetition rate reached as low as 10 Hz, resulting in pulse energy and peak power of 0.32 nJ and 1.5 kW, respectively. Second-harmonic generation of the low repetition rate pulse train was also produced by using a PPLN crystal. This opens up the potential for using this laser in single photon detection experiments and as a seed laser for many applications. Keywords: Er-fiber laser, Passively mode-locked fiber laser, Nonlinear polarization rotation, Mach-Zehnder modulator, Fast electro-optic modulator. PACS: Fiber lasers, 42.55.Wd, Mode locking, 42.60.Fc.

Steady Q-switched erbium-doped fiber laser pulse generation by exploiting spider silk as a passive saturable absorber

Spider silk is a biomaterial composed of natural protein that possesses unique strength and biocompatibility. Spider silk was explored for the first time that act as a potential saturable absorber (SA) for steady Q-switched erbium-doped fiber laser pulse generation around 1569 nm. The biocompatibility of spider silk SA will lead to the realization of an environment that is free from hazardous precursors and undesirable byproducts. In this study, spider silk was directly deposited onto the end face of the fiber ferrule to complete the fiberized SA assembly. In optical characteristic context, the modulation depth of spider silk SA used was 26 % and its saturation intensity was 0.02 MW/cm2. Results showed that self-started Q-switched at 30 mW threshold pump power was achieved. It was also interesting to find that the repetition rate of spider silk SA increased from 7 kHz to 29 kHz while the pulse width decreased from 32 µs to 10 µs. The signal-to-noise ratio (SNR) of the fundamental frequency was 54 dB, confirming the good stability of the pulsed laser. The highest output power and pulse energy measured at the pump power of 200 mW were 0.04 mW and 1.4 nJ respectively. In a nutshell, these results indicate that spider silk can be a viable alternative to real SA for producing laser at the 1570 nm region and spider silk-based SA can be equally with or even superior to the commonly employed SAs, which then opens up new possibilities for pulsed laser source applications.

Fe2O3 Nanoparticle-Based Q-Switched Pulse Fiber Laser

We demonstrate the utilization of iron oxide (Fe2O3) as light-absorbing material in an erbium-doped fiber laser (EDFL) for the generation of Q-switched pulses. A sandwich-type saturable absorber (SA) with Fe2O3 nanoparticles between fiber ferrules is proposed. A fiber ferrule tip is tapped onto a cap of index-matching gel, which is then dipped into Fe2O3 nanoparticle powder to allow its deposition through the adhesion effect. By incorporating Fe2O3–SA in an EDFL, self-started and stable Q-switched pulses are attained at a threshold power of 50.1 mW. The pulse repetition rate is tunable from 9.92 kHz to 22.47 kHz, whereas the pulse duration reduces from 38.4 µs to 13.8 µs with the pump power increment. The maximum pulse energy achieved is 36.9 nJ. This work offers a simple integration method of Fe2O3 nanoparticles as potential SAs for the generation of Q-switched pulses.

Parallel dual‐cavity fiber‐optic F‐P salinity sensor based on hollow core fiber and ceramic ferrule

AbstractA parallel dual‐cavity fiber‐optic Fabry‐Perot (F‐P) salinity sensor based on hollow core fiber and a ceramic ferrule is proposed. The sensor is comprised of a F‐P reference cavity and a F‐P sensing cavity in parallel. The reference cavity is a closed cavity that is fusion spliced with a segment of single‐mode optical fiber (SMF) and a small piece of silica tube (ST). The sensing cavity is an open liquid cavity that is connected by a ferrule after inserting two single‐mode fibers into a ceramic core, facilitating the replacement of salt water. Variations in the salinity of salt water will affect the change in refractive index of optical path, and then change the output spectral structure. By precisely controlling the length of two cavities, the free spectral range (FSR) of the sensing cavity is approximately equal to the FSR of the reference cavity, resulting in the generation of the Vernier effect, which improves the sensitivity of the sensor to salinity greatly. From the experimental results, it can be seen that the sensor sensitivity to salinity reaches −0.78 nm/‰ (−3809.68 nm/RIU) in the salinity range from 35‰ to 20‰ at room temperature of 25°C, which is 10.8 times higher than the sensitivity of a single sensing cavity. The enhancement factor is generally consistent with theoretical analysis results.

Laser Welding of Fiber and Quartz Glass Ferrule.

Optical fiber sensors fabricated by bonding have several limitations. To address these limitations, a CO2 laser welding process for an optical fiber and quartz glass ferrule is proposed in this study. A deep penetration welding method with optimal penetration (penetrating the base material only) is presented to weld a workpiece according to the requirements of the optical fiber light transmission, size characteristics of the optical fiber, and the keyhole effect of the deep penetration laser welding. Moreover, the influence of laser action time on the keyhole penetration is studied. Finally, laser welding is performed with a frequency of 24 kHz, power of 60 W, and duty cycle of 80% for 0.9 s. Subsequently, the optical fiber is subjected to out-of-focus annealing (0.83 mm, 20% duty cycle). The results show that deep penetration welding produces a perfect welding spot and has good quality; the hole generated from deep penetration welding has a smooth surface; the fiber can bear a maximum tensile force of 1.766 N. The performance of the optical fiber sensor is stable, and the maximum pressure deviation corresponding to the cavity length fluctuation is about 7.2 Pa. Additionally, the linear correlation coefficient R of the sensor is 0.99998.

Graphitic carbon nitride modulated short pulse generation in an Erbium-doped fiber laser

In the present study, a few layered graphitic carbon nitrides (g-C3N4) nano-sheets were successfully manufactured by the calcination method. It demonstrates nonlinear optical (NLO) property with modulation depths of ∼4.26% at 1.5 μ m. The index-matching gel adhesion effect was used to place the g-C3N4 nano-sheets on the fiber ferrule surface to produce short-pulsed lasers. The g-C3N4 saturable absorber (SA) based Q-switched erbium-doped fiber laser (EDFL) emits at 1560.5 nm wavelength with 1.2 nm of spectral bandwidth at 3 dB. The radio frequency's signal-to-noise ratio (SNR) is 42 dB at first harmonic, demonstrating excellent pulse stability. As the pump power increases, the frequency increases from 27.2 to 108 kHz, and the pulse shortens from 14.6 to 4.2 μ s, correspondingly. The highest pulse energy, peak power, and average output power are measured to be 48.7 nJ, 11 mW, and 5.18 mW at the highest pump power of 479.1 mW. Besides, the morphology and structure of g-C3N4 were characterized by scanning electron microscopy (SEM) and X-rays powder diffraction (XRD), photoluminescence (PL) spectra, Raman spectroscopy, Fourier transform infrared spectra (FT-IR), and UV- diffuse reflectance spectroscopy (DRS) have been also presented. Additionally, the stability of g–C3N4–SA was also measured. These findings suggest that few layered g-C3N4 nano-sheets have a substantial role as a SA in optical modulation devices and nonlinear optical properties at the near and mid-infrared band.

Impact of Intracavity Power Variations toward Ultrashort Pulse Generation

This study demonstrates a passive mode-locked erbium-doped fiber laser with a graphene nanoplatelet-saturable absorber (GNP-SA) that generates ultrashort pulses within femtosecond pulse duration. The GNP-SA is fabricated via a direct transfer approach by mechanically exfoliated graphene on a fiber ferrule. Its characteristics include 0.8% modulation depth, 8.7 MW/cm2 saturation fluence, and 36.8% absorbance. The quality of ultrashort pulses is studied with a variation of intracavity circulating powers that is controlled through an optical coupler. By changing the light intensity in the cavity, the optical amplification property in the erbium-doped fiber is also impacted. The increment of the output coupling ratio increases the population inversion in the active gain medium, which leads to the change of lasing wavelength from 1558 to 1532 nm. Using a 50% output coupling ratio, the fiber laser generates 960 fs pulse duration, 11.08 MHz repetition rate, and 6.05 mW output power. This study contributes to the understanding of oscillating light behavior while changing its intracavity power that affects the optical amplification properties.

The role of saturable absorbers thickness in the Q-switching of the erbium-doped fiber laser

A passively Q-switched Erbium (Er3+) doped fiber laser (EDFL) based on a ZnO saturable absorber (SA) prepared using a pulsed laser deposition (PLD) technique is demonstrated. The in-situ monitoring of the thickness in the PLD system enabled the control of the SA’s thickness during the growth. The thickness of the SA was varied and the output characteristics of the fiber laser with all thicknesses are compared. This study reveals that the performance and efficiency of an EDFL including pulse repetition rates, pulse duration, pulse energy, peak power, stability, and signal-to-noise ratio can be improved by varying the thickness of the SA. Based on the thickness of the SA, the optimized results are also presented. These findings suggest that the thickness control of the SA film grown directly on the fiber ferrule facilitates much-improved EDFL that has potential applications in pulsed laser sources.

Q-switched pulse operation in erbium-doped fiber laser subject to CdS nanoparticles-based saturable absorber deposit directly on the fiber ferrule

In this work, we demonstrate the performance of a Q-switched erbium-doped fiber laser (EDFL) using a cadmium-sulfide (CdS) nanoparticle-based saturable absorber (SA). The CdS nanoparticles were deposited on the fiber ferrule using the adhesion effect of the index matching gel. By incorporating the CdS nanoparticles on the fiber ferrule, a self-starting and stable Q-switched operation started under 11.2 mW pump power. As the pump power of EDFL based on the CdS-SA was increased from 11.2 to 297 mW, the emission wavelength varied from 1564.16 nm to 1568.83 nm, the pulse repetition rates, and pulse duration ranged from 20 to 90.25 kHz and 15.2 to 3.5 μs, respectively. The maximum average output power, pulse energy, and peak power were measured as 2.55 mW, 28.26 nJ, and 8.07 mW, respectively at a maximum available pump power of 297 mW. Furthermore, the stability of EDFL based on CdS nanoparticles based SA was further investigated. This study suggests that CdS nanoparticles-based SA offers an easy fabrication and integration of SA inside the laser cavity to generate a pulse operation in fiber lasers.

Optical-thermally actuated graphene mechanical resonator for humidity sensing

This paper demonstrates an optical-thermally actuated multi-layer graphene resonator for humidity sensing. A ∼10-layered graphene resonator with a diameter of 125 µm peripherally clamped on the fiber ferrule end face was actuated to vibrate using the intensity-modulated laser, and the vibration was detected based on the optical fiber Fabry-Perot interference method. The humidity sensing experiment exhibited an up to 350 Hz/%RH humidity sensitivity in the range of 0–100 % RH at 25 °C, which was 10 times higher than those of the previously reported Quartz Crystal Microbalance (QCM)-based humidity sensors. Also, a good repeatability of the frequency-humidity response was observed for the presented graphene resonator. Moreover, in view of the coupling effect of temperature on the graphene resonator, the temperature drift of 0.942 kHz/°C was measured in the range of 25–50 °C, thereby inducing an absolute humidity error of about 0.6 g/(m3·°C).

Highly stable Fabry-Pérot fiber-optic modulation device based on the photothermal effect of V2C MXene

The photothermal effect of MXene has attracted considerable attention because of its vast application potential. In this study, a Fabry-Perot interferometer (FPI)-based fiber-optic modulation device utilizing the good photothermal effect and high thermal conductivity of MXene V2C was realized. The modulation device was fabricated by forming a reflective FPI structure with two layers composed of a polymer layer and a MXene V2C layer on top of a fiber ferrule facet. An excellent pump-to-phase conversion efficiency of 0.332 π/mW was achieved using the device, which is larger than the values of other types of two-dimensional material-based photothermal modulation devices. The extinction ratio (ER) was ∼16.44 dB. The rise and fall time constants were ∼10 ms and ∼9 ms, respectively. The stability of the fabricated device was also investigated; the standard deviations of the extinction ratio and resonance wavelength fluctuation were 0.103 % and 0.002 nm, respectively.

Novel low-cost high-speed optic–electric laser diode pigtail module packaging technology

• At present, the research and development of high-speed laser modules for communication are designed with ceramic components globally. • In module packaging without the ceramic part, the misalignment caused by the deformation results in coupling efficiency loss. • A new type of high-speed laser diode pigtail module is designed to change the structure of a laser module and remove ceramic and process parts. • A laser diode pigtail module package achieves the best coupling efficiency. A high-speed laser diode pigtail for wide-band fiber-optic communications is a key component in optical fiber user loop systems, optical fiber data communication systems, and cable television systems. With the advent of a new type of optic–electric high-speed laser, wide-band communication has emerged. These three systems constitute future mainstreams of optical fiber communications. However, high-speed laser diode pigtails used in module components and process assembly account for extremely high production costs. The proposed pigtail module eliminates ceramic parts and facilitates mass production of the components. An optic fiber (including a jacket) was placed into a ferrule sleeve. The optic fiber did not undergo laser damage, and its stability in the reliability test was ensured by the plastic jacket. The optic fiber terminal surfaces grind the 7° angle to enhance the surface quality of the connector, thereby avoiding reflection and incurring a power loss of 4%. Moreover, achieving alignment in a conventional laser module package without a ceramic part and fiber ferrule is a considerable challenge, and apparently, there are still some issues that need to be resolved. In conventional optical fiber module package, laser welding technique provides a superior joint strength. However, in module packaging without the ceramic part, the misalignment caused by the deformation results in coupling efficiency loss. Therefore, a novel design of laser diode pigtail module packaging is necessary. A transmitter optical subassembly device, receiver optical subassembly device, and transceiver pigtail module can be manufactured in a unified process package. By applying the low-cost packaging technique, the cost and fabrication time of the module packaging were reduced, and the fabrication yield was increased.