Doped Fluoride Fiber Amplifier Research Articles

2.3 W, Linearly-Polarized Superfluorescent Generation From a Polarization-Maintaining Er3+-Doped Fluoride Fiber Amplifier Around 2.8 μm

We present a high-power, polarization-maintaining (PM) Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -doped fluoride fiber amplifier, which enables watt- level, linearly-polarized (LP) superfluorescent outputs around 2.8 μm by using a non-PM Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -doped fluoride fiber superfluorescent source (FSS) after polarization controlling as the seed. Based on an optimized scheme, the gained superfluorescent signal with a 20 dB bandwidth of 95 nm (2710∼2805 nm) can yield a maximum power of 2.32 W and a polarization extinction ratio (PER) of up to ∼23.6 dB. To our knowledge, this is the first demonstration of a mid-infrared (mid-IR) PM fiber amplifier, and the power also represents, until now, the highest level from a FSS in the mid-IR. Further power scaling is only limited by the seed power, and can be anticipated by boosting seed power or/and adopting multi-stage amplification. This work provides an alternative way for high-power, LP, mid-IR FSS, enabling a range of real-world applications.

Generation of single solitons tunable from 3 to 3.8 μm in cascaded Er3+-doped and Dy3+-doped fluoride fiber amplifiers

High-power tunable femtosecond mid-infrared (MIR) pulses are of great interest for many scientific and industrial applications. Here we demonstrate a compact fluoride-fiber-based system that generates single solitons tunable from 3 to 3.8 μm. The system is composed of an Er:ZBLAN fiber oscillator and amplifier followed by a fusion-spliced Dy:ZBLAN fiber amplifier. The Er:ZBLAN fiber amplifier acts as a power booster as well as a frequency shifter to generate Raman solitons up to 3 μm. The Dy:ZBLAN fiber amplifier transfers the energy from the residual 2.8 μm radiation into the Raman solitons using an in-band pumping scheme, and further extends the wavelength up to 3.8 μm. Common residual pump radiation and secondary solitons accompanying the soliton self-frequency shift (SSFS) are recycled to amplify Raman solitons, consequently displaying a higher output power and pulse energy, a wider shifting range, and an excellent spectral purity. Stable 252 fs pulses at 3.8 μm with a record average power of 1.6 W and a pulse energy of 23 nJ are generated. This work provides an effective way to develop high-power widely tunable ultrafast single-soliton MIR laser sources, and this method can facilitate the design of other SSFS-based laser systems for single-soliton generation.

Dual stage fiber amplifier operating near 3 µm with milijoule-level, sub-ns pulses at 5 W.

We report a 2800 nm Er3+-doped fluoride fiber amplifier that delivers 1 mJ pulses with an average power of 5 W and pulse duration of 1 ns at 5 kHz repetition rate. To the best of our knowledge, this is the highest pulse energy achieved from a fluoride-fiber-based system operating near 3 µm, and the W-level average power and short pulse lengths make the system a promising tool for biomaterials processing.

Compact CNT Mode-locked Ho $^{3+}$ -doped Fluoride Fiber Laser at 1.2 μm

A diode laser pumped carbon nanotube mode-locked Ho3+-doped fluoride fiber laser at 1.2 μm was demonstrated for the first time. Stable mode-locked pulses with an average power of 1 mW at a repetition rate of 18.47 MHz were obtained at a pump power of 348 mW. The pulse energy and peak power of this mode-locked laser oscillator were about 54 pJ and 12.6 W, and were increased to 2.41 nJ and 0.54 kW, respectively, by using a 15-cm Ho 3+-doped fluoride fiber amplifier. The pulse duration was measured to be 4.3 ps by an autocorrelator. Because the operation wavelength is close to the zero-dispersion wavelength of 1.3 μm, this mode-locked fiber laser exhibits unique features.

Excited states Tm spectroscopy in ZBLAN glass for S-band amplifier

We report on excited state spectroscopy measurements of Tm doped ZBLAN glass designed for fiber amplifier in the 1.48 μm wavelength range. Low temperature absorption, emission and Excited State Excitation measurements are reported to clearly identify the transitions involved in the different pump mechanisms of this Thulium Doped Fluoride fiber Amplifier. Room and low temperature Excited State Absorption spectra were recorded and quantitative determination of absorption cross sections has been obtained which allows to further proceed to a modeling of this amplifier.

Analysis of gain and noise performance of bidirectionally pumped Pr 3+ -doped fluoride fibre amplifier configurations with unbalanced pumping

Analysis of gain and noise performance of bidirectionally pumped Pr 3+ -doped fluoride fibre amplifier configurations with unbalanced pumping

Analysis of gain and noise performance of bidirectionally pumped Pr3+-doped fluoride fibre amplifier configurations with unbalanced pumping

This paper presents a numerical study of the performance of asymmetric bidirectionally pumped and reflective-type amplifier configurations in the unsaturated and saturated regions. The dependences of the optimum relative backward pump power on the fibre parameters and on the amplifier's working conditions for each configuration are analysed. This study has been made in the framework of the European Project COST 241: Characterization of Active Fibres for the Photonic Network.

Gain-flattened tellurite-based EDFA with a flat amplification bandwidth of 76 nm

We describe a tellurite-based Er/sup 3+/-doped fiber amplifier (EDFA) with a flat amplification bandwidth of 76 nm and a noise figure of less than 7 dB. Furthermore, a parallel-type amplifier composed of this EDFA and a 1.45-/spl mu/m-band Tm/sup 3+/-doped fluoride fiber amplifier achieved a flat amplification bandwidth of 113 nm.

Fast power transients in concatenated Pr/sup 3+/-doped fluoride fiber amplifiers

Amplified multiwavelength optical communication networks are prone to substantial saturation induced power fluctuations when a channel is turned on or rerouted. This perturbs amplifier gains at other wavelengths. The effects of addition and/or dropping of wavelength channels due to network reconfigurations or line failures in a multiwavelength network comprising eight concatenated Pr/sup 3+/-doped fluoride fiber amplifiers (PDFFAs) have been studied theoretically. A large-signal numerical model which incorporates time variation effects and the downstream and upstream propagation of signal, pump and amplified spontaneous emission has been used. In an eight channel WDM network the loss of channels will cause very fast power excursions of the surviving channels. The necessary speed of the link control circuit for surviving channel protection has been investigated.

Modelling of the temporal response of -doped fluoride fibre amplifiers

This paper presents a theoretical modelling and a numerical evaluation of the performance in the kHz regime of a typical praseodymium-doped fluoride fibre amplifier. The transient response of the amplifier is studied and amplifier characteristics such as saturation-induced second- and third-order distortion and interchannel interference, which become important in real telecommunication systems, are analysed in detail for amplitude-modulated signals.

Low-noise and gain-flattened fluoride-based Er 3+ -dopedfibre amplifier pumped by 0.97 µm laser diode

The authors demonstrate a gain-flattened Er3+-doped fluoride fibre amplifier with low noise amplification characteristics which employs 0.97 µm laser diode pumping. Excellent flat amplification is achieved with an average signal gain of 12.5 dB and a gain excursion of &lt; 1.0 dB, with a noise figure of 4.7 ± 0.2 dB for an 8 channel WDM signal in the 1532–1560 nm wavelength region. The authors confirm that an Er3+-doped fluoride fibre can be excited effectively to the 4I11/2 level by shifting the pump wavelength from 0.98 to 0.97 µm.

Pr/sup 3+/-doped fluoride fiber amplifier module pumped by a fiber coupled master oscillator/power amplifier laser diode

We constructed the first Pr/sup 3+/-doped fluoride fiber amplifier (PDFA) module pumped by a fiber-coupled master oscillator/power amplifier laser diode (MOPA-LD) operating at 1.017 μm. The maximum signal gain and noise figure were 30.5 and 5.5 dB, respectively. An output power of 18 dBm was achieved at an input signal power of 0 dBm. Furthermore, we showed that the use of MOPA-LD pumping, rather than conventional Nd-YLF laser pumping, makes it possible to halve the length of the Pr/sup 3+/-doped fluoride required in the amplifier module and also allows a broader spectral bandwidth to be achieved.

Optical Fiber Amplifiers and Their Applications. 1.6.MU.m-Band Rare-Earth-Doped Fiber Amplifier.

1.6μm band fiber amplifiers must be developed for future optical transmission line monitoring systems and ultra-wide band wavelength division multiplexing systems. The 1.6μm band Er3+-doped fiber amplifier (EDFA) and the Tm3+-doped fluoride fiber amplifier have been proposed as candidates. The former can be realized by shifting the amplification band of a 1.55μm band EDFA, by using a long Er3+-doped fiber. The latter employs the tail of the 1.8μm amplification band of Tm3+-doped fluoride fiber by the doping of terbium ions in the cladding. This paper reviews the amplification mechanisms and basic characteristics of 1.6μm band EDFAs and TDFAs.

Low noise characteristics of an AM-VSB video signaltransmission using a PDFA pumped by InGaAs semiconductor lasers through fibreBragg gratings

The authors have demonstrated 15 dBm output Pr/sup 3+/ doped fluoride fibre amplifiers (PDFAs) pumped by two high-power, and wavelength stabilised, InGaAs semiconductor lasers and also the low noise characteristics of AM-VSB video signal transmission using a PDFA. The wavelength of the InGaAs pumping semiconductor lasers was locked through fibre Bragg gratings, resulting in a reduction of the white-line noise in a CATV experiment, which is caused by the mode-hopping of the pumping sources.

Efficient distortion-free amplification of 1.3 μm femtosecond pulses in a Pr 3+-doped fluoride fiber amplifier

Amplification of ultrashort pulses in rate earth doped fiber amplifiers is governed by the combined effects of gain, dispersion and the intrinsic fiber nonlinearities (mainly the optical Kerr effect). This may lead to a serious degradation of the pulse quality, especially if the influence of the nonlinear effects becomes strong. In this work we demonstrate that the use of an amplifying fiber with a large group velocity dispersion effectively suppresses the deleterious influence of the fiber nonlinearities through Chirped Pulse Amplification in the active fiber. Efficient (up to ∼ 20 dB), distortion-free amplification of 340 fs pulses in a Pr 3+-doped fluoride fiber amplifier at 1.3 μm is reported for the first time. This result is important in view of many short pulse applications in the fields of ultrafast spectroscopy, optical signal processing and optical communications.

High-speed operation of an optically amplified system in the first telecommunications (800-850 nm) window

A diode pumped, commercially packaged, thulium doped fluoride fiber amplifier, (TDFFA) operating in the region of 0.8 /spl mu/m has been used in a series of high speed (1.2 Gb/s) systems experiments in the 1st telecommunications window. The results of this work indicate that the application of this amplifier unit could have significant benefits for future LAN/MAN type systems architectures involving large signal splits to customer premises.

Transmission of 5 ps solitons at 1.32 µm over50 km of standard fibre using praseodymium doped fluoride fibre amplifiers

The authors report the amplification of 5 ps duration pulses from a gain-switched 1.32 µm DFB laser using a praseodymium doped fluoride fibre amplifier, and their subsequent soliton transmission over 50 km of standard telecommunications fibre.

Subpicosecond pulse generation from a 1.3 µmDFB lasergain-switched at 1 GHz

Pulses from a 1.3 µm gain-switched DFB laser are amplified using a praseodymium doped fluoride fibre amplifier, and then compressed to as short as 240 fs using higher-order soliton compression. Techniques for pedestal minimisation are investigated.

Experimental measurement of gain in erbium-doped fluoride fiber amplifier in the 850-nm signal band

In this letter, we report an efficient single-mode Er/sup 3+/ doped fluoride fiber amplifier (EDFFA) in the 850 mn signal band. The Ti-sapphire laser was used to pump the EDFFA at 792 mm with an estimated absorbed pump power of 35 mW. The EDFFA used a 4.2 meter long NA=0.39, /spl lambda//sub c/=850 nm fluoride fiber as the active medium. A peak gain of 25 dB was observed at 852 mm. The gain was measured for a 10 nm region between 847.5 mn and 857.5 nm. The 3 dB gain bandwidth is less than 3 nm. However, the gain exceeded 20 dB over wavelength region of at least 7.5 nm. The gain and the gain bandwidth can be further increased by optimizing the length of the active fiber.

Optically amplified first window systems experiments

A diode pumped, commercially packaged, thulium doped fluoride fiber amplifier (TDFFA) operating in the region of 0.8 /spl mu/m has been characterized. The unit is capable of producing large small signal gains, low noise figures and high saturated output powers. A power amplifier slope efficiency of 62% has been achieved at 810 nm. The same TDFFA unit was used in a series of systems experiments, at data rates of 310 Mb/s and 1.2 Gb/s, in the first telecommunications window. The results of this work indicate that data can be transmitted over /spl ap/10 km lengths of both singlemode and standard transmission fiber, while still allowing significant margin to split the signal to a number of customers. The application of the TDFFA could therefore have significant benefit for future LAN/MAN type systems architectures involving large signal splits to customer's premises.