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To Investigate and Develop a Reduced Cost, Completely Monolithic High Energy Ultrafast Fiber Amplifier Based on Microstructured Fiber and Counter Pumping.
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Giant Pulse Phenomena in a High Gain Erbium Doped Fiber Amplifier
High gain Erbium Doped Fiber Amplifiers (EDFAs) are vulnerable to optical damage when unseeded, e.g. due to nonlinear effects that produce random, spontaneous Q-switched (SQS) pulses with high peak power, i.e. giant pulses. Giant pulses can damage either the components within a high gain EDFA or external components and systems coupled to the EDFA. We explore the conditions under which a reflective, polarization-maintaining (PM), core-pumped high gain EDFA generates giant pulses, provide details on the evolution of normal pulses into giant pulses, and provide results on the transient effects of giant pulses on an amplifier's fused-fiber couplers, an effect which we call Fiber Overload Induced Leakage (FOIL). While FOIL's effect on fused-fiber couplers is temporary, its damage to forward pump lasers in a high gain EDFA can be permanent.
Giant Pulse Phenomena in a High Gain Erbium Doped Fiber Amplifier
High gain Erbium Doped Fiber Amplifiers (EDFAs), while revolutionizing optical communications, remain vulnerable to optical damage when unseeded, e.g. due to nonlinear effects that produce random pulses with high peak power, i.e. giant pulses. Giant pulses can damage the components in a high gain EDFA or external components and systems coupled to the EDFA. We explore the conditions under which a reflective, polarization-maintaining (PM), core-pumped high gain EDFA generates giant pulses, provide details on conditions under which normal pulses evolve into giant pulses, and provide results on the transient effects of giant pulses on amplifier's fused-fiber couplers, an effect which we call Fiber Overload Induced Leakage (FOIL). While FOIL's effect on fused-fiber couplers is temporary, its damage to forward pump lasers in a high gain EDFA can be permanent.
Spectrally tailored supercontinuum generation from single-mode-fiber amplifiers
Spectral filtering of an all-normal-dispersion Yb-doped fiber laser was demonstrated effective for broadband supercontinuum generation in the picosecond time region. The picosecond pump pulses were tailored in spectrum with 1 nm band-pass filter installed between two single-mode fiber amplifiers. By tuning the spectral filter around 1028 nm, four-wave mixing was initiated in a photonic crystal fiber spliced with single-mode fiber, as manifested by the simultaneous generation of Stokes wave at 1076 nm and anti-Stokes wave at 984 nm. Four-wave mixing took place in cascade with the influence of stimulated Raman scattering and eventually extended the output spectrum more than 900 nm of 10 dB bandwidth. This technique allows smooth octave supercontinuum generation by using simple single-mode fiber amplifiers rather than complicated multistage large-mode-area fiber amplifiers.
32 Channel × 40 Gb/s WDM optical communication system utilizing different configurations of hybrid fiber amplifier
In this paper, a simulation analysis of 40 Gb/s wavelength division multiplexing system of 32 channels is implemented through RZ modulation format by using a different hybrid fiber amplifier (HFA) configurations, namely, serial HFA, parallel HFA, and combined serial–parallel hybrid fiber amplifier (CSP-HFA). The performance of the proposed amplifiers is compared in terms of average gain level, average noise figure, flat gain bandwidth. In addition, quality factor, bit error rate, and eye diagram for the demonstrated 32 channel × 40 Gb/s wavelength division multiplexing optical communication system utilizing different configurations of the hybrid fiber amplifier is compared. The CSP-HFA shows better performance than serial and parallel hybrid amplifiers in terms of wider flat gain bandwidth, higher quality factor, lower bit error rate, and wider and clearer eye opening. Furthermore, CSP-HFA exhibits a flat gain bandwidth of 65 nm with an acceptable average gain of 16 dB and average noise figure of 7 dB.
Erbium-doped fiber amplifier elements for structural analysis sensors
The use of erbium-doped fiber amplifiers (EDFA's) in optical fiber sensor systems for structural analysis is described. EDFA's were developed for primary applications as periodic regenerator amplifiers in long-distance fiber-based communication systems. Their in-line amplification performance also makes them attractive for optical fiber sensor systems which require long effective lengths or the synthesis of special length-dependent signal processing functions. Sensor geometries incorporating EDFA's in recirculating and multiple loop sensors are discussed. Noise and polarization birefringence are also considered, and the experimental development of system components is discussed.
Broadband spectral combining of three pulse-shaped fiber amplifiers with 42fs compressed pulse duration
We demonstrate ultra-broadband spectral combining of ultrashort pulses from Yb-doped fiber amplifiers, with coherently spectrally synthesized pulse shaping, to achieve tens-of-fs pulses. This method can fully compensate for gain narrowing and high order dispersion over broad bandwidth. We produce 42fs pulses by spectrally synthesizing three chirped-pulse fiber amplifiers and two programmable pulse shapers across an 80nm overall bandwidth. To the best of our knowledge, this is the shortest pulse duration achieved from a spectrally combined fiber system at one-micron wavelength. This work provides a path toward high-energy, tens-of-fs fiber chirped-pulse amplification systems.
2-.mu.m fiber amplified spontaneous emission (ASE) source
A 2-.mu.m fiber Amplified Spontaneous Emission (ASE) source provides a wide emission bandwidth and improved spectral stability/purity for a given output power. The fiber ASE source is formed from a heavy metal oxide multicomponent glass selected from germanate, tellurite and bismuth oxides and doped with high concentrations, 0.5-15 wt. %, thulium oxides (Tm.sub.2O.sub.3) or 0.1-5 wt% holmium oxides (Ho.sub.2O.sub.3) or mixtures thereof. The high concentration of thulium dopants provide highly efficient pump absorption and high quantum efficiency. Co-doping of Tm and Ho can broaden the ASE spectrum.
Quartz enhanced photoacoustic H{sub 2}S gas sensor based on a fiber-amplifier source and a custom tuning fork with large prong spacing
A quartz enhanced photoacoustic spectroscopy (QEPAS) sensor, employing an erbium-doped fiber amplified laser source and a custom quartz tuning fork (QTF) with its two prongs spaced ∼800 μm apart, is reported. The sensor employs an acoustic micro-resonator (AmR) which is assembled in an “on-beam” QEPAS configuration. Both length and vertical position of the AmR are optimized in terms of signal-to-noise ratio, significantly improving the QEPAS detection sensitivity by a factor of ∼40, compared to the case of a sensor using a bare custom QTF. The fiber-amplifier-enhanced QEPAS sensor is applied to H{sub 2}S trace gas detection, reaching a sensitivity of ∼890 ppb at 1 s integration time, similar to those obtained with a power-enhanced QEPAS sensor equipped with a standard QTF, but with the advantages of easy optical alignment, simple installation, and long-term stability.
Generation of 180 W average green power from a frequency-doubled picosecond rod fiber amplifier
Here, we report on the generation of 180 W average green power from a frequency-doubled picosecond rod fiber amplifier. In an Yb-doped fiber master-oscillator-power-amplifier system, 2.3-ps 704 MHz pulses are first amplified in small-core fibers and then in large-mode-area rod fibers to produce 270 W average infrared power with a high polarization extinction ratio and diffraction-limited beam quality. By carrying out frequency doubling in a lithium triborate (LBO) crystal, 180 W average green power is generated. To the best of our knowledge, this is the highest average green power achieved in fiber-based laser systems.
High-power continuous-wave mid-infrared radiation generated by difference frequency mixing of diode-laser-seeded fiber amplifiers and its application to dual-beam spectroscopy
We report the generation of up to 0.7 mW of narrow-linewidth (<60-MHz) radiation at 3.3 micrometers by difference frequency mixing of a Nd:YAG-seeded 1.6-W Yb fiber amplifier and a 1.5-micrometers diode-laser-seeded 0.6-W Er/Yb fiber amplifier in periodically poled LiNbO3. A conversion efficiency of 0.09%/W (0.47 mWW-2 cm-1) was achieved. A room-air CH4 spectrum acquired with a compact 80-m multipass cell and a dual-beam spectroscopic configuration indicates an absorption sensitivity of +/-2.8 x 10(-5) (+/-1 sigma), corresponding to a sub-parts-in-10(9) (ppb) CH4 sensitivity (0.8 ppb).
E-band neodymium-doped fiber amplifier: model and application
To analyze recent experiments with a neodymium-doped fiber amplifier operating in the E-band of wavelengths (1350–1450 nm) and embedded in fused silica, we develop a time-dependent model consisting of rate equations for the aggregate ion populations and the radiation intensities along the amplifier axis. Both copropagating and counterpropagating intensities, including amplified spontaneous emission, are incorporated. The wavelength-dependent cross section for excited state absorption is inferred from auxiliary measurements. Steady-state solutions are obtained over a range of seed wavelengths and powers. The resulting gain curves agree with experiment at low to intermediate powers (less than ~1 mW). With a proposed addition to the system loss, the agreement extends to saturation (~100 mW).
Polarization Maintaining, Very-Large-Mode Area, Er Fiber Amplifier for High Energy Pulses at 1572.3 nm
We demonstrate the first polarization maintaining, very-large-mode-area Er-doped fiber amplifier with ~1000 square micron effective area. The amplifier is core pumped by a Raman fiber laser and is used to generate single frequency one microsecond pulses with pulse energy of 368 microJoules, M2 of 1.1, and polarization extinction greater than 20 dB. The amplifier operates at 1572.3 nm, a wavelength useful for trace atmospheric CO2 detection.
Multi-Frequency Soliton Complex in Er/Yb-Doped Fiber Amplifier
We experimentally investigated presence of multi-frequency soliton complex that exist in high power Er/Yb-doped Fiber Amplifier. The complex with the spectral bandwidth in excess of 100 nm is bound by the Kerr nonlinearity and exhibit stable propagation.
Mid-infrared difference-frequency generation source pumped by 1.1-1.5 micrometer dual-wavelength fiber amplifier for trace-gas detection
Continuous-wave mid-infrared radiation near 3.5 micrometers is generated by difference-frequency mixing of the output of a compact 1.1-1.5 micrometer dual-wavelength fiber amplifier in periodically poled LiNbO3. The diode side-pumped amplifier is constructed with double-cladding Yb-doped fiber followed by single-mode Er/Yb codoped fiber. Output powers of as much as 11 microW at 3.4 micrometers are obtained, and spectroscopic detection of CH4 and H2CO is demonstrated. c 1998 Optical Society of America.
A 980 nm pseudomorphic single quantum well laser for pumping erbium-doped optical fiber amplifiers
The authors have fabricated ridge waveguide pseudomorphic InGaAs/GaAs/AlGaAs GRIN-SCH SQW (graded-index separate-confinement-heterostructure single-quantum-well) lasers, emitting at 980 nm, with a maximum output power of 240 mW from one facet and a 22 percent coupling efficiency into a 1.55-micron single-mode optical fiber. These lasers satisfy the requirements on efficient and compact pump sources for Er3+-doped fiber amplifiers.
High-power single-element pseudomorphic InGaAs/GaAs/AlGaAs single quantum well lasers for pumping Er-doped fiber amplifiers
A 980-nm-ridge waveguide pseudomorphic InGaAs/GaAs/AlGaAs single-quantum-well laser with a maximum single-ended output power of 240 mW from a facet-coated device is fabricated from a graded-index separate-confinement heterostructure grown by molecular-beam epitaxy. The laser oscillates in the fundamental spatial mode, allowing 22 percent coupling efficiency into a 1.55-micron single-mode optical fiber. Life testing at an output power of 30 mW per facet from uncoated devices reveals a superior reliability to GaAs/AlGaAs quantum-well lasers but also the need for protective facet coatings for long term reliability at power levels required for pumping Er-doped fiber amplifiers.