Multiwavelength Brillouin-erbium Fiber Laser Research Articles

Formation, properties and role of residual waves as seeds in multiwavelength Brillouin-erbium fiber laser

The formation, properties and role of residual waves of a multiwavelength Brillouin-erbium fiber laser (BEFL) which are responsible for the enhancement of the number of spectral lines in the BEFL are discussed and explored. The formation process which involves interplay of stimulated Brillouin scattering, Rayleigh scattering and four-wave mixing (FWM) in a highly nonlinear fiber is explained in this work. The properties of the residual waves (forward propagation) in terms of output spectra, output power and optical signal to noise ratio are compared with the waves of the BEFL (backward propagation) for better understanding. We find experimentally that the residual waves span over a wide band due to the mechanism of FWM and this is believed to play a key role in generating seeds for lasers in the BEFL. The present analysis of the formation, properties and role of the residual waves can well explain how the residual waves enhance the number of spectral lines and this understanding could be useful in creating quality seeds for the BEFL.

Impact of Booster Section Length on the Performance of Linear Cavity Brillouin-Erbium Fiber Laser

The impact of booster section length made from passive erbium-doped fiber (EDF) on the L-band multiwavelength Brillouin-Erbium fiber laser (MBEFL) is studied experimentally in this paper. The influence on the performance of MBEFL in term of number of generated Stokes lines, tuning range and lasing threshold were investigated. A comparison was made between MBEFL without a booster section and with booster sections of different lengths. Through comparative study and at fixed BP power and 100mW of 1480 pump power, longer passive EDF length of 5m exhibits the highest average number of Stokes lines of 23 with tuning range of 14nm. In contrast, shorter passive EDF length of 1m shows the highest tuning range of 17nm and an average number of 21 Stokes lines.

Q-switched multi-wavelength Brillouin erbium fiber laser

In this paper, a demonstration of performance of a multi-wavelength Brillouin Erbium Fiber Laser (BEFL) with double Brillouin spacing (DBS) output comb and Q-switching characteristics featuring a figure-of-eight configuration is presented. It utilizes a four-port circulator to discriminate the odd and even order Stokes lines which allows, using 7 km long dispersion shifted fiber (DSF), the generation of a spectrum with DBS, multi-wavelength comb of nine lasing lines and a 0.16 nm spacing. The Q-switched pulse trains are obtained from the proposed BEFL configured with the DSF and pumped at 1480 nm and power ranging from 20 mW to 40 mW based on relaxation oscillation technique. It has the highest repetition rate of 609 kHz and the smallest pulse width of 0.73 μs at the pump power of 40 mW. The highest pulse energy of 6.15 nJ is obtained at pump power of 30 mW. The repetition rate and pulse width of the BEFL are reduced by replacing the DSF with 10 km long nonzero dispersion shifted fiber (NZ-DSF).

Tunable Brillouin-erbium fiber laser incorporating a low-cost biconic tapered fiber

A new method of tuning a multi-wavelength Brillouin-erbium fiber laser (BEFL) within a Fabry–Perot cavity by incorporating a low-cost biconic tapered fiber is reported. The biconic tapered fiber was fabricated using a flame elongation technique and it was incorporated into the BEFL system to position the self-lasing cavity modes over a tuning range of 5.5 nm within the erbium-doped fiber gain profile. By injecting the Brillouin pump near to the tunable self-lasing cavity modes, it suppresses the modes and generates stable cascaded Brillouin–Stokes lines with more than 20 dB signal-to-noise ratio.

Tunable multiwavelength L-band Brillouin-Erbium fiber laser utilizing passive EDF absorber section

We demonstrate a simple tunable L-band multiwavelength Brillouin-Erbium fiber laser that utilizes a short passive erbium doped fiber (PEDF) as an absorber section. The impact of including the PEDF absorber section on the laser tunability is investigated. The proposed laser structure exhibits a wide tuning range of 24.4nm (from 1583.5nm to 1607.9nm) at 1480nm pump and Brillouin pump powers of 100 and 4mW, respectively. This tuning range represents a 31% increase compared with a laser without a PEDF absorber section. The average number of stable output channels produced within this wavelength range is 16 channels with a spacing of 0.089nm.

Broadly tunable multiwavelength Brillouin-erbium fiber laser using a twin-core fiber coupler

A tunable multiwavelength Brillouin-erbium fiber laser (MW-BEFL) using a twin-core fiber (TCF) coupler is proposed and demonstrated. The TCF coupler is formed by splicing a section of TCF between two single-mode fibers. By simply applying bending curvature on the TCF coupler, the peak net gain is shifted close to the Brillouin pump (BP), which has advantage for suppressing self-lasing cavity modes with low-BP-power injection. In this work, the dependency of the Stokes signals tuning range on the free spectral range (FSR) of TCF coupler is studied. It is also found that the tuning range of MW-BEFL can exceed the FSR of TCF coupler by adopting proper BP power and 980-nm pump power. Up to 40 nm tuning range of MW-BEFL in the absence of self-lasing cavity modes is achieved.

Low threshold multiwavelength Brillouin–erbium fiber laser generation in conjunction with a photonic crystal fiber

We propose and demonstrate the most compact low threshold multiwavelength Brillouin–erbium fiber laser (MBEFL) incorporating a 100-m long photonic crystal fiber (PCF) as a Brillouin gain medium. This optimized configuration with a simple ring cavity makes it possible for the first time to achieve more than 22 Brillouin Stokes waves with a line spacing of 0.08 nm (∼10 GHz) and more than −20 dBm power in conjunction with a 100-m long PCF. Using a pre-amplified Brillouin power approach in a ring cavity realizes a low threshold multiwavelength laser with a Brillouin pump power of around 8 dBm at an injected 980 nm pump power of 125 mW. Anti-Stokes lines are also obtained due to four-wave mixing and bidirectional operation.

Investigation of Q-Switching Characteristics in Single- and Double-Spacing Multi-Wavelength Brillouin Erbium Fiber Laser

A multi-wavelength Brillouin erbium fiber laser (BEFL) with a Q-switching characteristic is demonstrated using a piece of non-zero dispersion shifted fiber (NZ-DSF) as a Brillouin gain medium (BGM) in conjunction with relaxation oscillation technique. The performance of the multi-wavelength short pulse generation is investigated for two different BEFL configurations for single and double Brillouin spacing outputs. The Q-switched BEFL generates a pulse train with repetition rates of 10.36 and 20.41 kHz whose corresponding pulse widths are 13.21 and 3.84 μs for the single and double Brillouin spacing outputs, respectively. The self-starting pulses are obtained within a low 1480-nm pump power region at a slightly higher power than the lasing threshold power. This pulse laser based on stimulated Brillouin scattering (SBS) is fairly stable at room temperature.

150-Channel Four Wave Mixing Based Multiwavelength Brillouin-Erbium Doped Fiber Laser

A wide band tunable multiwavelength Brillouin-erbium fiber laser (BEFL) is developed. In this structure, the laser is formed between a double pass amplification box and a highly nonlinear fiber (HNLF), which acts as a virtual mirror, results in removing the reflective physical mirror from one side of the laser structure. A large number of Stokes and anti-Stokes lines are generated through cascading stimulated Brillouin scattering and inducing four wave mixing process inside the HNLF. Due to optimizing Brillouin and erbium doped fiber (EDF) pump powers, the Rayleigh back scattering is efficiently suppressed, and the generated BEFL wavelengths are free from self lasing cavity modes over a wide tuning range. At EDF pump power and Brillouin pump power of 100 mW and 3 dBm, respectively, up to 150 Stokes lines with wavelength spacing of 0.076 nm, and a tuning range of 40 nm were achieved.

A Multi-Wavelength Brillouin Erbium Fiber Laser With Double Brillouin Frequency Spacing and Q-Switching Characteristics

A multiwavelength Brillouin Erbium fiber laser (MWBEFL) with double brillouin frequency spacing and Q-switching characteristics is demonstrated based on figure-of-eight configuration. The proposed MWBEFL uses a four-port circulator as a double-frequency shifter to isolate and circulate the odd-stokes signals through the Brillouin gain medium. Multiwavelength combs with 14 and 8 lasing lines and spacing of 0.16 nm are obtained by the use of 10-km long nonzero dispersion shifted fiber (NZDSF) and 2-km long dispersion compensating fiber (DCF), respectively. The Q-switched pulse trains are obtained in the proposed MWBEFL at 1480-nm pump power within 29 to 40 mW. It has repetition rates of 20.4 and 104.2 kHz with the corresponding pulse widths of 3.84 and 1.03 μs using the NZDSF and DCF, respectively, as the gain medium.

MULTIWAVELENGTH BRILLOUIN-ERBIUM FIBER LASER GENERATION WITH DOUBLE-BRILLOUIN-FREQUENCY SPACING IN A RING CAVITY

We propose and demonstrate the most compact and stable multiwavelength Brillouin Erbium Fibre Laser (MBEFL) by incorporating a 10-km long nonzero dispersion shifted fiber (NZ-DSF) acting as a Brillouin gain medium. This proposed configuration with only a single ring cavity is able to produce odd-order Brillouin Stokes waves appear in the backward direction with the line spacing 0.16nm (~20GHz). Brillouin pump and the even Stokes orders act as a Brillouin pump in the forward direction using a pre-amplified Brillouin power approach in a ring cavity. Up to 12 odd-order Brillouin Stokes lines are observed with the Brillouin pump power of around 8 dBm at injected 980 nm pump power of 125 mW. The anti-Stokes lines are also obtained due to four wave mixing and bidirectional operation.

Tunable Multiwavelength Brillouin-Erbium Fiber Laser Based on Fiber Amplified Loop

A novel linear multiwavelength Brillouin-erbium fiber laser based on a nonlinear fiber amplified loop is demonstrated. The nonlinear fiber amplified loop induces wavelength-dependent cavity loss and it provides flexibility on controlling the amount of light reflected and transmitted into and out of the laser's cavity. At the Brillouin pump (BP) power of 25 mW and the 980 nm pump power of 200 mW, 21 output channels with 0.08 nm channel spacing are achieved. We realize the tunable output of multiwavelength through adjusting the polarization controller and the BP wavelength. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1741–1743, 2013

Widely tunable L-band multiwavelength brillouin-erbium fiber laser incorporating a bismuth-based erbium-doped fiber

We have demonstrated a widely wavelength tunable Brillouin-erbium fiber laser (BEFL) with multiwavelength lasing in the L-band region. The Brillouin pump (BP) is injected from the external cavity and preamplified by an intracavity bismuth-based erbium-doped fiber amplifier (Bi-EDFA) before entering the single-mode fiber. By combining the broadband gain of Bi-EDFA and BP preamplification technique within the linear cavity, our BEFL exhibits a broad tuning range of 65 nm from 1555 to 1620 nm, which is the widest one achieved in L-band BEFLs to the best of our knowledge. The maximum number of wavelengths obtained within this wavelength range is 12 channels with a spacing of approximately 0.088 nm. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1574–1577, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27664

A widely tunable double-Brillouin-frequency spaced multiwavelength fiber laser with a 110 nm tuning range

A wideband double-Brillouin-frequency spaced multiwavelength Brillouin–erbium fiber laser (MWBEFL) with 110 nm tuning range is demonstrated. The fiber laser utilizes simple compound-ring cavity structures which confine the odd-order Brillouin–Stokes (BS) signals within the right ring and couple out the initial Brillouin pump signal (BP) and even-order BS signals to generate a 0.176 nm spacing multiwavelength. A wavelength- and bandwidth-tunable optical band-pass filter (TBF) is used to manipulate the location of self-lasing cavity and to get a wideband tuning range. All the generated output channels exhibit good stability.

Simple multiwavelength Brillouin–Erbium-doped fiber laser structure based on short SSMF

An efficient multiwavelength Brillouin–Erbium fiber laser (BEFL) was developed by improving the feedback mechanism of Brillouin Stokes lines. The BEFL performance in terms of threshold power and wavelengths count was improved by using a new structure of double pass amplification cavity. The new structure utilized the variable optical coupler (VOA) not only as the input and output ports but also to form a fiber loop mirror that reduces the number of optical components, thus, only three optical components were needed. By optimizing the Brillouin and 1480nm pump power, up to 41 channels and 26 channels were obtained using 0.6km and 0.3km long of standard single mode fiber (SSMF), respectively.

Flattening effect of four wave mixing on multiwavelength Brillouin-erbium fiber laser

A multiwavelength Brillouin-erbium fiber laser with enhanced output uniformity is demonstrated and its performance with and without the assistance of four wave mixing (FWM) is compared. The presence of FWM effect is proven by the generation of anti-Stokes wave and higher-order Stokes wave. This scheme is successful in flattening the multiwavelength output. At Brillouin pump wavelength of 1,550 nm, between the first and the last output channel, peak power differences of 4.59 and 8.32 dB are recorded for the scheme with and without the assistance of FWM, respectively. This represents 3.73 dB improvement in the multiwavelength output power uniformity.

A Q-switched multi-wavelength Brillouin erbium fiber laser with a single-walled carbon nanotube saturable absorber

A Q-switched multi-wavelength Brillouin erbium fiber laser (MWBEFL) is demonstrated using a single-walled carbon nanotube–polyethylene oxide (SWCNT–PEO) saturable absorber (SA). The SA is fabricated by cutting off a small part of the developed SWCNT–PEO film and sandwiching it in between two FC/PC (fiber connector/physical contact) fiber connectors. Multi-wavelength combs with ten lasing lines and spacing of 0.158 nm are obtained by the use of 2 km long dispersion compensating fiber as the Brillouin gain medium and a four-port circulator to isolate and circulate the odd-order Stokes signals. Q-switched pulse trains with a repetition rate of 105.2 kHz and a pulse width of 0.996 μs are obtained in the proposed MWBEFL at a 1480 nm pump power of 120 mW and a Brillouin pump power of 5.4 dBm.

Generation of efficient 20 GHz optical combs in a Brillouin-erbium fiber laser

A tunable multiwavelength Brillouin-erbium fiber laser is experimentally demonstrated with a double-Brillouin-frequency spacing. This double-frequency shifter is constructed by incorporating a four-port circulator to isolate and circulate the odd-Stokes signals through the 10 km long non-zero dispersion shifted fiber, which acts as a Brillouin gain medium. The output even-order Stokes signals are amplified in the erbium gain block formed in a ring cavity. Up to 15 lasing lines with a wavelength spacing of 0.173 nm have been achieved at a 980 nm pump power of 50 mW and a Brillouin pump of 3 dB m. The multiwavelength laser source exhibits a 10 nm tuning range from 1552 to 1562 nm with the optical signal-to-noise ratio of the desired output channels at around 34.5 dB.

Double spacing multi-wavelength L-band Brillouin erbium fiber laser with Raman pump

A new multi-wavelength Brillouin erbium fiber laser (BEFL), which operates in the L-band region with double frequency Brillouin spacing, is demonstrated. This design uses a Raman pump (RP) and a piece of 2 km highly nonlinear fiber as a gain medium. The double frequency spacing is achieved by employing a dual ring configuration, which is formed by utilizing a four-port circulator that removes the odd-order Stoke signals. Twenty Stokes and seventeen anti-Stokes lines, which have optical signal to noise ratio (OSNR) greater than 15 dB, are generated simultaneously with a spacing of 0.16 nm when Brillouin pump and RP powers were fixed at the optimum values of 8 dBm and 40 mW, respectively. The BEFL can be tuned in the range between 1591 nm to 1618 nm. The proposed configuration increases the number of lines generated and the OSNR, and thus allows a compact multi-wavelength laser source to be realized.

Widely Tunable C $+$ L Bands Multiwavelength BEFL With Double-Brillouin Frequency Shifts

A wideband multiwavelength Brillouin–erbium fiber laser (BEFL) with double Brillouin frequency spacing is demonstrated. The fiber laser structure utilizes a tunable band-pass filter and a pre-amplified Brillouin pump technique within a ring cavity. An average of six Brillouin–Stokes signals in C <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$+$</tex></formula> L bands with a constant wavelength spacing of 0.174 nm can be turned over a span of 80 nm from 1530 nm to 1610 nm. Total average output power of 8.5 mW from this laser structure was achieved. All the generated Brillouin–Stokes signals exhibit good stability, and high peak power of above <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex></formula> 10 dBm per signal was demonstrated.