All-Fiber erbium doped fiber laser based on an intracavity polarizing fiber grating

Using Aston-made special design polarizing grating, we have implemented a stretchpulse mode locked erbium fiber laser. The laser has a simple and efficient all-fiber configuration with 90 fs output pulse duration and1.68 nJ pulse energy

23 MHz widely wavelength-tunable L-band dissipative soliton from an all-fiber Er-doped laser

Via careful choice of Er-doped fiber length in the cavity, a widely wavelength-tunable L-band dissipative soliton all-fiber Er-doped laser incorporating a L-band optimized polarizing fiber grating device is experimentally demonstrated. The laser delivers 15.38 ps dissipative soliton pulses centered at 1597.34 nm with 3 dB bandwidth of 34.6 nm under 622 mW pump power. The pulse repetition rate is 23 MHz. After using single mode fiber at external cavity, the pulse duration is compressed to 772 fs. With nonlinear polarization rotation-based intracavity comb filter, the central wavelength of the generated dissipative soliton can be tuned from 1567 nm to 1606 nm with a spectral tuning range of 39 nm, which, to the best of our knowledge, is the widest tuning range yet reported for a dissipative soliton fiber laser working in communication band

Stable nanosecond passively Q-switched all-fiber erbium-doped laser with a 45° tilted fiber grating

Nanosecond passive Q-switching generation from an all-fiber erbium-doped laser with a UV inscribed 45° tilted fiber grating (TFG) is systematically demonstrated. The 45° TFG is employed as a polarizer together with two polarization controllers (PCs) to realize nonlinear polarization rotation (NPR). Because of the NPR effect, stable Q-switched pulses with an average output power of 17.5 mW, a single pulse energy of 72.7 nJ, a repetition rate of 241 kHz, a pulse width of 466 ns, and a signal to noise ratio (SNR) of 58.8 dB are obtained with 600 mW pump power. To the best of our knowledge, the SNR is the highest among all-fiber passively Q-switched erbium-doped laser. The stability of this erbium-doped fiber laser (EDFL) is also examined by monitoring the laser consecutively for 5 h under laboratory conditions

Wavelength-tunable passively mode-locked Erbium-doped fiber laser based on carbon nanotube and a 45° tilted fiber grating

A wavelength-tunable all-fiber Erbium-doped mode-locked fiber laser based on carbon nanotubes and 45° tilted fiber grating (TFG) is demonstrated. We investigated the effect of PDL of 45TFG in the tuning range of a mode locked laser. The central wavelength of the laser can be tuned continuously from 1559.85 nm to 1564.46 nm with a tuning range of 4.6 nm using a weak 45TFG and from 1553.37 nm to 1568.63 nm with a tuning range of 15.26 nm using a strong 45TFG. The laser maintains high signal to noise ratio >50 dB across all the wavelength tuning range

Complete characterization of ultrashort pulse sources at 1550 nm

This paper reviews the use of frequency-resolved optical gating (FROG) to characterize mode-locked lasers producing ultrashort pulses suitable for high-capacity optical communications systems at wavelengths around 1550 nm, Second harmonic generation (SHG) FROG is used to characterize pulses from a passively mode-locked erbium-doped fiber laser, and both single-mode and dual-mode gain-switched semiconductor lasers. The compression of gain-switched pulses in dispersion compensating fiber is also studied using SHG-FROG, allowing optimal compression conditions to be determined without a priori assumptions about pulse characteristics. We also describe a fiber-based FROG geometry exploiting cross-phase modulation and show that it is ideally suited to pulse characterization at optical communications wavelengths. This technique has been used to characterize picosecond pulses with energy as low as 24 pJ, giving results in excellent agreement with SHG-FROG characterization, and without any temporal ambiguity in the retrieved puls

Continuous Wave and Pulsed Erbium-Doped Fiber Lasers for Microwave Photonics Applications

El objetivo de esta tesis es el diseño, fabricación y caracterización de láseres de fibra como fuentes ópticas compactas con aplicaciones de fotónica de microondas, como son la generación de ondas en la banda de microondas-milimétricas y la conversión analógico-digital asistida ópitcamente. Las prestaciones de la tecnología electrónica en estas aplicaciones están limitadas para frecuencias de trabajo de decenas de GHZ. En este contexto, la tecnología óptica ha encontrado aplicaciones potenciales con el fin de extender las especificaciones de sistemas de microondas tradicionales. En particular, los láseres de de fibra se presentan como fuentes ópticas fiables de coste reducido las cuales están ganando interés como soluciones compactas en comparación con láseres de estado sólido. Esta tesis presenta el desarrrollo de un láser de fibra de realimentación distribuida capaz de emitir en dos longitudes de onda en régimen continuo para la generación de señales de microondas por fotomezclado. La cavidad óptica está constituida por una red de difracción de Bragg grabada en una fibra dopada con erbio, en la que se aplican dos desfases puntuales. La sintonización dinámica de la diferencia de frecuencia de los dos modos emitidos se lleva a cabo mediante el empleo de dos actuadores piezoeléctricos controlados por una fuente de tensión continua. Tras la fotodetección de la salida del láser se obtiene una señal de microondas con un rango de sintonización continuo de 0.12-7 GHz. La máxima frecuencia de sintonización viene limitada por el ancho de banda espectral de la red de difracción. Por ello, se ha estudiado una segunda configuración del láser con el fin de incrementar el rango de sintonización. La implementación de dos cavidades de realimentación distribuida con diferentes frecuencias de emisión en la misma fibra dopada permite un control más versátil de las frecuencias de emisión de ambos modos ópticos. Esta fuente altamente compacta y sencilla es capaz de proporcionar unVillanueva Ibáñez, GE. (2012). Continuous Wave and Pulsed Erbium-Doped Fiber Lasers for Microwave Photonics Applications [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/17801Palanci

Erbium doped fiber lasers based on 45° tilted fiber gratings

45° tilted fiber grating (TFG) possesses a series of merits, such as strong polarization dependant loss (PDL), low insertion loss, superior compatibility, and compactness. One of the most prominent features of such polarizing device is the all-fiber structure. This polarizing element plays an important role in all-fiber integrated systems which have been widely investigated in the last two decades. In this report, we reviewed the recent development in single wavelength, multiple wavelength, Q-switched, and mode locked fiber lasers based on the 45°TFG as in-fiber polarizer

L-band GHz femtosecond passively harmonic mode-locked Er-doped fiber laser based on nonlinear polarization rotation

Via using an L-band optimized in-fiber polarizing grating device, a GHz L-band femtosecond passively harmonic mode-locked (PHML) Er-doped fiber laser based on nonlinear polarization rotation (NPR) is firstly demonstrated. 4.22 GHz pulses with the duration of 810 fs and super-mode suppression ratio (SMSR) of 32 dB are obtained under the pump power of 712 mW corresponding to 215th harmonic order. The central wavelength of 4.22 GHz pulses is 1581.7 nm with 10.1 nm 3-dB bandwidth. Furthermore, under this fixed pump power, higher harmonic orders can also be attained by rotating the polarization controllers (PCs) properly. The highest repetition rate we obtained is 7.41 GHz with the SMSR of 20.7 dB

Ultra-long mode-locked Er-droped fibre lasers

The development of ultra-long (UL) cavity (hundreds of meters to several kilometres) mode-locked fibre lasers for the generation of high-energy light pulses with relatively low (sub-megahertz) repetition rates has emerged as a new rapidly advancing area of laser physics. The first demonstration of high pulse energy laser of this type was followed by a number of publications from many research groups on long-cavity Ytterbium and Erbium lasers featuring a variety of configurations with rather different mode-locked operations. The substantial interest to this new approach is stimulated both by non-trivial underlying physics and by the potential of high pulse energy laser sources with unique parameters for a range of applications in industry, bio-medicine, metrology and telecommunications. It is well known, that pulse generation regimes in mode-locked fibre lasers are determined by the intra-cavity balance between the effects of dispersion and non-linearity, and the processes of energy attenuation and amplification. The highest per-pulse energy has been achieved in normal-dispersion UL fibre lasers mode-locked through nonlinear polarization evolution (NPE) for self-modelocking operation. In such lasers are generated the so-called dissipative optical solitons. The uncompensated net normal dispersion in long-cavity resonatorsusually leads to very high chirp and, consequently, to a relatively long duration of generated pulses. This thesis presents the results of research Er-doped ultra-long (more than 1 km cavity length) fibre lasers mode-locked based on NPE. The self-mode-locked erbium-based 3.5-km-long all-fiber laser with the 1.7 µJ pulse energy at a wavelength of 1.55 µm was developed as a part of this research. It has resulted in direct generation of short laser pulses with an ultralow repetition rate of 35.1 kHz. The laser cavity has net normal-dispersion and has been fabricated from commercially-available telecom fibers and optical-fiber elements. Its unconventional linear-ring design with compensation for polarization instability ensures high reliability of the self-mode-locking operation, despite the use of a non polarization-maintaining fibers. The single pulse generation regime in all-fibre erbium mode-locking laser based on NPE with a record cavity length of 25 km was demonstrated. Modelocked lasers with such a long cavity have never been studied before. Our result shows a feasibility of stable mode-locked operation even for an ultra-long cavity length. A new design of fibre laser cavity – “y-configuration”, that offers a range of new functionalities for optimization and stabilization of mode-locked lasing regimes was proposed. This novel cavity configuration has been successfully implemented into a long-cavity normal-dispersion self-mode-locked Er-fibre laser. In particular, it features compensation for polarization instability, suppression of ASE, reduction of pulse duration, prevention of in-cavity wave breaking, and stabilization of the lasing wavelength. This laser along with a specially designed double-pass EDFA have allowed us to demonstrate anenvironmentally stable all-fibre laser system able to deliver sub-nanosecond high-energy pulses with low level of ASE noise

Widely Wavelength-tunable Mode-locked Fiber Laser Based on a 45° Tilted Fiber Grating and Polarization Maintaining Fiber

We present a passively mode-locked Erbium-doped fiber laser with tunable parameters including central wavelength, 3-dB bandwidth, and pulse duration. The mode-locking mechanism of the laser is realized by using single-walled carbon nanotubes (SWCNTs) polyvinyl alcohol composite film as a saturable absorber. The tunable operation is implemented via a fiber birefringence filter consisting of a polarization maintaining (PM) fiber and a Brewster fiber grating. The laser achieves a maximum spectral tuning range of 36 nm with 8-cm PM fiber. The maximum spectral width variation of 5.19 nm is acquired when the PM fiber is 12 cm. Simultaneously, the spectral widths of pulses at different central wavelengths are also adjustable. Furthermore, the total cavity length is 8.28 m, which is the shortest cavity length to obtain such wide tuning range in an Erbium-doped fiber laser based on SWCNTs