Showing papers on "Dispersion-shifted fiber published in 2017"
TL;DR: In this paper, a fiber all-optical phase shifter using few-layer 2D material tungsten disulfide (WS2) deposited on a tapered fiber was demonstrated.
Abstract: All-optical phase shifters and switches play an important role for various all-optical applications including all-optical signal processing, sensing and communication. In this paper, we demonstrate a fiber all-optical phase shifter using few-layer 2D material tungsten disulfide (WS2) deposited on a tapered fiber. WS2 absorbs injected 980 nm pump (control light) and generates heat, which changes the refractive index of both WS2 and tapered fiber due to thermo-optic effect and achieves a maximum phase shift of 6.1π near 1550 nm. The device has a loss of 3.7 dB. By constructing a Mach-Zehnder interferometer with WS2 based phase shifter in one arm, an all-optical switch is also obtained with an extinction ratio of 15 dB and a rise time of 7.3 ms. This all fiber low-cost and compact optical phase shifter and switch demonstrates the potential of 2D transition metal dichalcogenides for all-optical signal processing devices.
98 citations
TL;DR: In this paper, a mode-locked all-fiber laser based on the nonlinear multimode interference (NL-MMI) effect of the graded-index multimode fiber (GIMF) is proposed and demonstrated.
Abstract: A mode-locked all-fiber laser based on the nonlinear multimode interference (NL-MMI) effect of the graded-index multimode fiber (GIMF) is proposed and demonstrated. The saturable absorber (SA) used in the laser consists of a step-index multimode fiber (SIMF) connected by a GIMF. Compared with the theoretically proposed SMF–GIMF–SMF structure, the introduction of the SIMF eliminates the restriction on the length of the GIMF and provides a more flexible method of making an SA based on the NL-MMI. Through bending the device to a certain state, the modulation depth of the SA was measured to be 3.16%. The mode-locked laser output pulses have the pulsewidth of ∼446 fs, the bandwidth of 4.48 nm, and the fundamental repetition rate of 11.73 MHz. This versatility and simplicity of the SA device combined with the possibility of scaling the pulse energy in the large-mode-area double-clad fiber laser make it highly attractive in ultrafast photonics.
95 citations
TL;DR: In this paper, a porous core circular photonic crystal fiber (PC-CPCF) with ultra-low material loss for efficient terahertz wave transmission is presented.
93 citations
TL;DR: In this article, the authors demonstrate the generation of mode-locked pulses from a double-clad ytterbium-doped fiber laser employing a saturable absorber (SA) made of a few layers of black phosphorus (BP).
Abstract: We demonstrate the generation of mode-locked pulses from a double-clad ytterbium-doped fiber laser (YDFL) employing a saturable absorber (SA) made of a few layers of black phosphorus (BP). The BP SA was prepared by mechanically exfoliating BP crystal and spreading the acquired BP flakes on a piece of scotch tape. The tape was then sandwiched between two ferrules and incorporated in a YDFL cavity to achieve a stable mode-locked operation at 1085.58 nm with a repetition rate of 13.5 MHz. A maximum pulse energy of 5.93 nJ was obtained at pump power of 1322 mW with the output power of 80 mW. Our study may well be the first demonstration of the BP-based mode-locked fiber laser that should shed some new insights into two-dimensional layer materials related photonics.
91 citations
TL;DR: A fiber laser which is continuously tunable from 1 to 1.9 μm is reported, a random distributed feedback Raman fiber laser pumped by a tunable Yb doped fiber laser that both stimulated Raman scattering gain and Rayleigh scattering feedback are available at any wavelength.
Abstract: The wavelength tunability of conventional fiber lasers are limited by the bandwidth of gain spectrum and the tunability of feedback mechanism. Here a fiber laser which is continuously tunable from 1 to 1.9 μm is reported. It is a random distributed feedback Raman fiber laser, pumped by a tunable Yb doped fiber laser. The ultra-wide wavelength tunability is enabled by the unique property of random distributed feedback Raman fiber laser that both stimulated Raman scattering gain and Rayleigh scattering feedback are available at any wavelength. The dispersion property of the gain fiber is used to control the spectral purity of the laser output.
89 citations
TL;DR: This Letter reports the first monolithic erbium-doped fluorozirconate fiber laser bounded by two fiber Bragg gratings operating at 3.55 μm, the highest ever achieved at this wavelength from a fiber laser and presents numerical modeling results exhibiting remarkable agreement with experimental results.
Abstract: We report, to the best of our knowledge, the first monolithic erbium-doped fluorozirconate fiber laser bounded by two fiber Bragg gratings (FBGs) operating at 3.55 μm. Its output power and total optical efficiency are 5.6 W and 26.4% respectively, the highest ever achieved at this wavelength from a fiber laser. The monolithic design of the cavity also increases its stability and prevents fiber tip damage which has limited prior demonstrations to a maximum output power of 1.5 W. This Letter also studies the performances of the laser cavity for various output FBG reflectivities and presents numerical modeling results exhibiting remarkable agreement with experimental results.
80 citations
TL;DR: This is the highest output power of single-frequency polarization-maintained fiber amplifier based on an all-fiber structure and the slope efficiency of the main amplifier is about 80%.
Abstract: A high-power 1064 nm single-frequency polarization-maintained fiber amplifier based on an all-fiber master oscillator power amplifier configuration is demonstrated. To mitigate the stimulated Brillouin scattering (SBS) and the mode instability (MI) effect, a polarization-maintained Yb-doped fiber with a high dopant concentration and a 25 μm core diameter is adopted in the main amplifier stage; in addition, step-distributed longitudinal strain is imposed on the active fiber to broaden its effective SBS gain spectrum and further increase the SBS threshold. As a result, a pump-limited 414 W single-frequency fiber laser is obtained without signs of SBS and MI. Experimental results show that the SBS threshold is increased by at least two times. The slope efficiency of the main amplifier is about 80%. The polarization degree is higher than 98% at all the power levels. The beam quality is measured with a M2 of 1.34. To the best of our knowledge, this is the highest output power of single-frequency polarization-maintained fiber amplifier based on an all-fiber structure.
74 citations
TL;DR: By incorporating the sample as a saturable absorber in the Erbium-doped fiber laser (EDFL), bandwidth of 20.5 nm and pulse duration of 200 fs were generated, which corresponded to the best mode-locking results obtained for all-fiber MoS2 saturation absorber at 1.5 µm wavelength.
Abstract: For the first time, we demonstrated the fabrication of mechanically exfoliated molybdenum disulfide (MoS2) samples deposited onto a D-shaped optical fiber. The MoS2 exfoliated flakes were deposited onto a stacked of 1.2 µm PVA (polyvinyl alcohol) and 300 nm PMMA (polymethyl methacrylate) layers and then transferred directly onto a side polished surface of D-shaped optical fiber with polishing length of 17 mm and no distance from the fiber core. The sample exhibited a high polarization performance as a polarizer with relative polarization extinction ratio of 97.5%. By incorporating the sample as a saturable absorber in the Erbium-doped fiber laser (EDFL), bandwidth of 20.5 nm and pulse duration of 200 fs were generated, which corresponded to the best mode-locking results obtained for all-fiber MoS2 saturable absorber at 1.5 µm wavelength.
62 citations
TL;DR: In this article, a few-mode ring-core fiber supporting only single-radial-order modes, which enables weak intermodal coupling between higher order modes and has potential to reduce the complexity of mode-division multiplexed digital signal processing.
Abstract: We report the design, fabrication, and characterization of a few-mode ring-core fiber supporting four mode groups (i.e., seven spatial modes including spatial degeneracies). By carefully designing the ring-core parameters, the fiber can support only single-radial-order modes, which enables weak intermodal coupling between higher order modes and has potential to reduce the complexity of mode-division multiplexed digital signal processing. The low loss (∼0.3 dB/km) and long length (25.3 km) RCF is successfully fabricated and they are both records for a ring-core fiber.
58 citations
TL;DR: In this article, a PANDA ring-core fiber (PM-PRCF) was proposed for space-division multiplexing applications with high contrast index ring and stress-induced birefringence.
Abstract: We present a polarization-maintaining PANDA ring-core fiber (PM-PRCF) characterized by the combination of a ring-core structure with two stress-applying rods. This special fiber design separates the adjacent modes and avoids the cutoff of the higher-order modes, which is a common problem in elliptical core polarization-maintaining few-mode fibers. Using a high-contrast index ring and stress-induced birefringence, the PM-PRCF features support for 10 vector modes, with effective refractive index separations from their adjacent modes >10−4. Broadband performance is investigated subsequently over a wide wavelength range from 1500 to 1630 nm. The proposed fiber is targeted at applications in space-division multiplexing while eliminating the complex multiple-input multiple-output signal processing.
58 citations
TL;DR: A novel amplification regime in a counter-pumped, relatively long (2 meters), large mode area, highly Yb-doped and polarization-maintaining tapered fiber, which offers a high peak power directly from the amplifier.
Abstract: We demonstrate a novel amplification regime in a counter-pumped, relatively long (2 meters), large mode area, highly Yb-doped and polarization-maintaining tapered fiber, which offers a high peak power directly from the amplifier. The main feature of this regime is that the amplifying signal propagates through a thin part of the tapered fiber without amplification and experiences an extremely high gain in the thick part of the tapered fiber, where most of the pump power is absorbed. In this regime, we have demonstrated 8 ps pulse amplification to a peak power of up to 0.76 MW, which is limited by appearance of stimulated Raman scattering. In the same regime, 28 ps chirped pulses are amplified to a peak power of 0.35 MW directly from the amplifier and then compressed with 70% efficiency to 315 ± 10 fs, corresponding to an estimated peak power of 22 MW.
TL;DR: In this article, the multimode optical fiber size effects on the performances of the clad-modified fiber with ZnO nanorods relative humidity (RH) sensor were experimentally investigated.
Abstract: In this work, the multimode optical fiber size effects on the performances of the clad-modified fiber with ZnO nanorods relative humidity (RH) sensor were experimentally investigated. Simple and controlled chemical etching method through on line monitoring was used to prepare different fiber waist diameter with long length of 15 mm. More precisely, the competition behavior of sensor performances with varying fiber waist diameter was studied to find appropriate size of maximizing evanescent fields. The obtained results revealed that evanescent wave absorption coefficient ( γ ) enhanced more than 10 times compare to bare fiber at the proposed optimum fiber diameter of 28 µm. Also, high linearity and fast recovery time about 7 s was obtained at the proposed fiber waist diameter. Applicable features of the proposed sensor allow this device to be used for humidity sensing applications, especially to be applied in remote sensing technologies.
TL;DR: In this article, an erbium-doped fiber laser based on a polarization-maintaining fiber Bragg grating (PM-FBG) and all-fiber Mach-Zehnder interferometer (MZI) was used to realize a quadruple-wavelength 1.5μm laser output.
Abstract: We propose the use of an erbium-doped fiber laser based on a polarization-maintaining fiber Bragg grating (PM-FBG) and all-fiber Mach–Zehnder interferometer (MZI) to realize a quadruple-wavelength 1.5-μm laser output. In the proposed system configuration, a 1535-nm center wavelength PM-FBG acts as the wavelength selector. The dual-pass MZI is fabricated using two couplers with a 50:50 splitting ratio, and the wavelength spacing of the comb is varied by using a spectrum power-driven optical fiber delay line inserted in MZI. The working threshold in the experiment is 82 mW. Tunable lasers of single-, dual-, triple-, and quadruple-wavelengths can be realized by adjusting the polarization controller. The generated wavelengths are in the range of 1534 to 1534.6 nm, the wavelength space is 0.2 nm, and the 3 dB linewidth is less than 0.05 nm. The power fluctuation is observed to be less than 0.912 dB, and the signal-to-noise ratio (SNR) is larger than 34.9 dB at 26 °C over a scan time of 10 min.
TL;DR: An optical Fabry-Perot interferometer fiber tip sensor based on an etched end of multimode fiber filled with ultraviolet adhesive that has a high potential in monitoring environment of high pressure.
Abstract: We demonstrate an optical Fabry-Perot interferometer fiber tip sensor based on an etched end of multimode fiber filled with ultraviolet adhesive. The fiber device is miniature (with diameter of less than 60 μm), robust and low cost, in a convenient reflection mode of operation, and has a very high gas pressure sensitivity of −40.94 nm/MPa, a large temperature sensitivity of 213 pm/°C within the range from 55 to 85 °C, and a relatively low temperature cross-sensitivity of 5.2 kPa/°C. This device has a high potential in monitoring environment of high pressure.
TL;DR: In this article, the femtosecond fundamental and harmonic mode-locked Er-doped fiber laser with WS2 solution saturable absorber (SSA) is presented.
Abstract: This study presents the femtosecond fundamental and harmonic mode-locked Er-doped fiber laser with WS2 solution saturable absorber (SSA). The SA is fabricated based on a D-shaped fiber (DF) embedded in WS2 nanosheets solution. Such WS2 solution has virtues of good antioxidant capacity, excellent scattering resistance, high heat dissipation, and high damage threshold. This kind of SA shows a modulation depth of 11%, a saturable intensity ${\rm I_{sat}}$ of 5 MW/cm2, and nonsaturable loss of 18%. By employing DF-WS2 SSA, a stable mode-locked fiber laser is achieved with repetition rate of 10.2 MHz and pulse duration of 660 fs. At the pump power of 350 mW, 460.7-MHz repetition rate harmonic mode-locking (HML) operation is also obtained, which corresponds to 45th harmonics of the fundamental cavity repetition rate. The pulse duration is 710 fs and signal-to-noise ratio is 66 dB, showing the excellent performance in HML fiber laser with SA. The results indicate that DF-WS2 solution can work as a potential SA for ultrafast nonlinear optics.
TL;DR: Through systematic characterization of the pump absorption and output power dependence on gas pressure, fiber length, and pump intensity, it is determined that the reduction of pump absorption at high pump flux and the degradation of gain performance at high gas pressure necessitate the use of increased gain fiber length for efficient lasing at higher powers.
Abstract: We report the characteristics of a 1 W hollow-core fiber gas laser emitting CW in the mid-IR. Our system is based on an acetylene-filled hollow-core optical fiber guiding with low losses at both the pump and laser wavelengths and operating in the single-pass amplified spontaneous emission regime. Through systematic characterization of the pump absorption and output power dependence on gas pressure, fiber length, and pump intensity, we determine that the reduction of pump absorption at high pump flux and the degradation of gain performance at high gas pressure necessitate the use of increased gain fiber length for efficient lasing at higher powers. Low fiber attenuation is therefore key to efficient high-power laser operation. We demonstrate 1.1 W output power at a 3.1 μm wavelength by using a high-power erbium-doped fiber amplifier pump in a single-pass configuration, approximately 400 times higher CW output power than in the ring cavity previously reported.
TL;DR: It is evident that RDF and hybrid RDF + DFF has presented the highest signal quality factor and optical nonlinearity signal processing in compared with other optical fibers communication channel.
Abstract: Our research presents best candidate different commercial optical fiber communication channel for optical nonlinearity signal processing in high optical transmission bit rate systems in the presence of traveling wave semiconductor optical amplifier (TW-OSA) These optical fibers that are namely dispersion flattened fiber (DFF), reverse dispersion fiber (RDF), non zero dispersion shifted fiber, dispersion compensated fiber, single mode fiber, and hybrid RDF + DFF Wavelength division multiplexing (WDM) system is employed to benefit 80 users with the high transmission bit rates up to 160 Gb/s over optical fiber communication channel length up to 200 km with trying to reduce nonlinearity effects by choosing suitable channel spacing and first or second order Bessel, Gaussian WDM Mux/Demux filter Maximum peak power, optical signal to noise ratio, and signal quality factor can be measured to test the system performance It is evident that RDF and hybrid RDF + DFF has presented the highest signal quality factor and optical nonlinearity signal processing in compared with other optical fibers communication channel The obtained results were done using optiwave system software simulation version 7
TL;DR: In this paper, a review of all the main approaches for dispersion compensation in optical networks is presented and a characterization of fiber Bragg grating is done using the reflection spectrum and group delay response analysis.
Abstract: Pulse spreading due to the dispersion causes the overlapping of the transmitted pulses at the receiver end known as inter symbol interference (ISI). The ISI thus limits transmission of high speed data. We are living in the age of bandwidth hungry and high speed applications, for which optical networks form the most important part because of its high bandwidth. In optical networks chromatic dispersion (CD) is one of the main obstacle in high speed transmission. Hence this CD is compensated by various approaches throughout the transmission system. A review of all the main approaches is presented in this paper. Characterization of fiber Bragg grating for dispersion compensation is done using the reflection spectrum and group delay response analysis.
TL;DR: In this paper, a pure silica core photonic crystal fiber with multicoating layers for high refractive index (RI) sensing is proposed, where Tantalum pentoxide is deposited on Au in order to prevent the oxidation and further enhance the evanescent field.
Abstract: A pure silica core photonic crystal fiber with multicoating layers for high refractive index (RI) sensing is proposed. Au is used as the active plasmonic material. Tantalum pentoxide is deposited on Au in order to prevent the oxidation and further enhance the evanescent field. The simulation was preformed through the full-vector finite element method (FEM), and the results show that the proposed fiber sensor can obtain the average wavelength sensitivity of 9180 nm/RIU with the analyte RI range of 1.40–1.44, corresponding to the resolution of 1.09 × 10–5 RIU. Moreover, the maximum amplitude sensitivity of 1739.26 RIU–1 with resolution of 5.75 × 10–6 RIU are also obtained. The designed sensor can be a potential candidate for microfluidic analyte detecting.
TL;DR: A high-power, high-efficiency Raman fiber laser pumped directly by laser diode modules at 978 nm is demonstrated, which is the highest power and highest efficiency Raman Fiber laser demonstrated in any configuration allowing brightness enhancement, regardless of pumping scheme.
Abstract: We demonstrate a high-power, high-efficiency Raman fiber laser pumped directly by laser diode modules at 978 nm. 154 W of CW power were obtained at a wavelength of 1023 nm with an optical to optical efficiency of 65%. A commercial graded-index (GRIN) core fiber acts as the Raman fiber in a power oscillator configuration, which includes spectral selection to prevent generation of the second Stokes. In addition, brightness enhancement of the pump beam by a factor of 8.4 is attained due to the Raman gain distribution profile in the GRIN fiber. To the best of our knowledge this is the highest power and highest efficiency Raman fiber laser demonstrated in any configuration allowing brightness enhancement (i.e., in either cladding-pumped configuration or with GRIN fibers, excluding step-index core pumped), regardless of pumping scheme (i.e., either diode pumped or fiber laser pumped).
TL;DR: This work presents nonlinear impairment mitigation of wavelength division multiplexed signals, through optical phase conjugation (OPC), and demonstrates the operation of the system using both 16 and 64-quadrature amplitude modulation (QAM) signals.
Abstract: We present nonlinear impairment mitigation of wavelength division multiplexed signals, through optical phase conjugation (OPC). We conduct our experiments on a 400-km-long installed fiber link equipped with erbium-doped fiber amplifiers, with the OPC placed close to the middle of the link. Our OPC configuration realizes efficient reuse of the signal bandwidth, avoiding the loss of half of the spectral band typical of most phase conjugating schemes. We demonstrate the operation of the system using both 16- and 64-quadrature amplitude modulation (QAM) signals and report Q-factor improvements up to 0.5 and 2.5 dB for 16- and 64-QAM, respectively.
TL;DR: High beam quality and narrow spectrum have been obtained in a Raman fiber laser based on a 1.1 km long graded-index fiber directly pumped by a multimode 915 nm laser diode.
Abstract: High beam quality and narrow spectrum have been obtained in a Raman fiber laser based on a 1.1 km long graded-index fiber directly pumped by a multimode 915 nm laser diode. The generation of a near-diffraction-limited beam at 954 nm with M2≤1.27 and Δλ=0.42 nm at an output power above 10 W is enabled by a cavity mirror made of a special fiber Bragg grating inscribed by a femtosecond technique in the central part of the graded-index fiber core.
TL;DR: Experimental results demonstrate that CTFBGs can increase the Raman threshold and promote the slope efficiency of the whole system, which is significant for further power scaling in high power oscillators and amplifiers.
Abstract: Stimulated Raman scattering (SRS) is one of the main limits for fiber lasers further power scaling. We report on the suppression of the stimulated Raman scattering in fiber laser amplifier using chirped and tilted fiber Bragg gratings (CTFBGs) for the first time. In this paper, we design and fabricate a CTFBG used to suppress the SRS in 1090 nm fiber laser output, and establish a system to test the effect of suppression. A maximum suppression ratio nearly 25 dB is achieved. Experimental results demonstrate that CTFBGs can increase the Raman threshold and promote the slope efficiency of the whole system, which is significant for further power scaling in high power oscillators and amplifiers.
TL;DR: In this paper, the authors investigated the hydrostatic pressure dependence of the Bragg wavelength of a fiber Bragg grating inscribed in a perfluorinated graded-index (PFGI-) polymer optical fiber (POF) at 1550 nm.
Abstract: We investigate the hydrostatic pressure dependence of the Bragg wavelength of a fiber Bragg grating (FBG) inscribed in a perfluorinated graded-index (PFGI-) polymer optical fiber (POF) at 1550 nm. At 0.5 MPa, the Bragg wavelength increased with time and became almost constant ~150 min later. Such a long time constant probably originates from the unique structure of the PFGI-POF, which has a thick overcladding around its core and cladding. The pressure-dependence coefficient without considering the time constant was estimated to be 1.3 nm/MPa; this is over five times the values of other types of POF-FBGs. This indicates that by removing the overcladding of the PFGI-POF, fast-response high-sensitivity pressure sensing will be feasible. Once the Bragg wavelength became constant at 0.5 MPa, the pressure-dependence coefficient of the Bragg wavelength was measured to be −0.13 nm/MPa, the absolute value of which was comparable with those of other POF-FBGs, but with an opposite sign.
TL;DR: In this article, an in-line Mach-Zehnder interferometer (MZI) is proposed and experimentally demonstrated by splicing a segment of seven-core fiber (SCF) and two segments of very short multi-mode fibers (MMFs).
Abstract: An in-line Mach–Zehnder interferometer (MZI) is proposed and experimentally demonstrated. The sensor is fabricated by splicing a segment of seven-core fiber (SCF) and two segments of very short multi-mode fibers (MMFs). The mode field of the MMF used in our experiments close to the region of hexagonally distributed fiber cores of the SCF, which help to obtain a higher coupling efficiency. A clear interference spectrum of the proposed MZI is obtained by injecting a broadband light into a lead-in single-mode fiber. Such an MZI could be used to realize the measurement of temperature and curvature. The temperature and curvature sensitivities are 55.81 pm/°C and 31.54 nm/ $\text{m}^{-1}$ , respectively.
TL;DR: A simple route to few-optical-cycle pulse generation from a mid-infrared fiber laser through nonlinear compression of pulses from a holmium-doped fiber oscillator using a short length of chalcogenide fiber and a grating pair is proposed.
Abstract: We propose and demonstrate a simple route to few-optical-cycle pulse generation from a mid-infrared fiber laser through nonlinear compression of pulses from a holmium-doped fiber oscillator using a short length of chalcogenide fiber and a grating pair. Pulses from the oscillator with 265-fs duration at 2.86 {\mu}m are spectrally broadened through self-phase modulation in step-index As2S3 fiber to 141-nm bandwidth and then re-compressed to 70 fs (7.3 optical cycles). These are the shortest pulses from a mid-infrared fiber system to date, and we note that our system is compact, robust, and uses only commercially available components. The scalability of this approach is also discussed, supported by numerical modeling.
TL;DR: This novel optical-fiber micro-displacement sensor based on surface plasmon resonance (SPR) is proposed by fabricating a Kretschmann configuration on graded-index multimode fiber (GIMMF) by employing a single-mode fiber to change the radial position of the incident beam as the displacement.
Abstract: We propose and demonstrate a novel optical-fiber micro-displacement sensor based on surface plasmon resonance (SPR) by fabricating a Kretschmann configuration on graded-index multimode fiber (GIMMF). We employ a single-mode fiber to change the radial position of the incident beam as the displacement. In the GIMMF, the angle between the light beam and fiber axis, which is closely related to the resonance angle, is changed by the displacement; thus, the resonance wavelength of the fiber SPR shifts. This micro-displacement fiber sensor has a wide detection range of 0–25 μm, a high sensitivity with maximum up to 10.32 nm/μm, and a nanometer resolution with minimum to 2 nm, which transcends almost all of other optical-fiber micro-displacement sensors. In addition, we also research that increasing the fiber polishing angle or medium refractive index can improve the sensitivity. This micro-displacement sensor will have a great significance in many industrial applications and provide a neoteric, rapid, and accurate optical measurement method in micro-displacement.
TL;DR: In this paper, a low-cost way of achieving a high sensitivity optical fiber strain sensor by introducing higher-order interference modes using a torsional multimode fiber (MMF) instead of normal MMF based on single-mode-multimode-single-mode (SMS) structure is proposed and the coupling mechanism of twist fiber is investigated theoretically.
TL;DR: In this article, the mid-infrared (MIR) emission behavior of Tb3+-doped Ge-As-Ga-Se bulk glasses and unstructured fiber was investigated when pumping at 2.013 or 2.95 μm.
Abstract: The mid-infrared (MIR) emission behavior of Tb3+-doped Ge–As–Ga–Se bulk glasses (500, 1000, and 1500 ppmw Tb3+) and unstructured fiber (500 ppmw Tb3+) is investigated when pumping at 2.013 μm. A broad emission band is observed at 4.3–6.0 μm corresponding to F57→F67, with an observed emission lifetime of 12.9 ms at 4.7 μm. The F47 level is depopulated nonradiatively and so it is proposed that Tb3+-doped Ge–As–Ga–Se fiber may operate as a quasi-three-level MIR fiber laser. Underlying glass-impurity vibrational absorption bands are numerically removed to give the true Tb3+ absorption cross section, as required for Judd–Ofelt (J–O) analysis. Radiative transition rates calculated from J–O theory are compared with measured lifetimes. A numerical model of the three-level Tb3+-doped fiber laser is developed for Tb3+ doping of 8.25×1024 ions m−3 (i.e., 500 ppmw) and dependence of laser performance on fiber length, output coupler reflectivity, pump wavelength, signal wavelength, and fiber background loss is calculated. Results indicate the feasibility of an efficient three-level MIR fiber laser operating within 4.5–5.3 μm, pumped at either 2.013 or 2.95 μm.
19 Mar 2017
TL;DR: Lowest-ever 0.1419-dB/km loss at 1560-nm wavelength was realized in a silica-core fiber with 1290-°C low fictive temperature, 147-μm2 large effective area and low microbending loss due to soft primary coating.
Abstract: Lowest-ever 0.1419-dB/km loss at 1560-nm wavelength was realized in a silica-core fiber with 1290-°C low fictive temperature, 147-μm2 large effective area and low microbending loss due to soft primary coating.