Brillouin Gain Medium Research Articles

L-Band Multiwavelength BEFL With Amplified Fiber Loop Mirror

An efficient L-band multiple-wavelength Brillouin-erbium fiber laser is presented. We configured a linear cavity resonator where the cavity ends are made up of high-reflectivity optical mirror on one side and an amplified fiber loop mirror on the other. This laser architecture provides amplification intensity-dependent transmission and allows the preamplification of the Brillouin pump (BP) signal before being injected into the Brillouin gain medium, i.e., the single-mode fiber (SMF). The technique ensures rapid reduction of erbium gain depletion, Brillouin gain saturation, and Brillouin threshold of the SMF thereby leading to the generation of higher number Brillouin Stokes lines. By utilizing only 8.5 dBm of the BP signal power, the proposed laser generates 54 Brillouin Stokes lines at BP signal wavelength of 1601.7 nm and 33 mW of the 1480-nm laser pump power. The generated channels are rigidly separated by 0.089 nm thereby becoming an attractive candidate to support the dense wavelength division multiplexing optical communication systems.

Multi-wavelength Brillouin fiber laser generation using dual-pass approach

A simple and compact multi-wavelength tunable Brillouin fiber laser (BFL) in conjunction with dual-pass approach is proposed and experimentally compared with the output of a conventional single ring cavity architecture. This BFL source is demonstrated using 10 km long non-zero dispersion shifted fiber (NZ-DSF) as a Brillouin gain medium. By single ring cavity configuration, odd-order Brillouin Stokes lines appear in the backward direction with the line spacing 0.16 nm (∼20 GHz) between each two consecutive waves. However, this single ring cavity in conjunction with dual-pass configuration is able to generate Brillouin Stokes lines with 0.08 nm spacing by providing bi-directional oscillations of Brillouin waves in both forward and backward directions. With a Brillouin pump power of 15.3 dBm, approximately up to 17 Brillouin Stokes lines are generated which is tunable over 40 nm tuning range.

Multiwavelength Brillouin-erbium fiber laser with double-Brillouin-frequency spacing

We demonstrate a multiwavelength Brillouin-erbium fiber laser with double-Brillouin-frequency spacing. The wider channel spacing is realized by circulating the odd-order Stokes signals in the Brillouin gain medium through a four-port circulator. The circulated odd-order Stokes signals are amplified by the Brillouin gain and thus produce even-order Stokes signals at the output. These signals are then amplified by erbium gain block to form a ring-cavity laser. Ten channels with 0.174 nm spacing that are generated at 0.5 mW Brillouin pump power and 150 mW pump power at 1480 nm can be tuned from 1556 nm to 1564 nm. The minimum optical signal-to-noise ratio of the generated output channels is 30 dB with maximum power fluctuations of ±0.5 dB.

Multi-wavelength Brillouin fiber laser using dual-cavity configuration

A simple technique for achieving multi-wavelength tunable multi-wavelength Brillouin fiber laser (BFL) based on dual-pass configuration is demonstrated. The BFL uses a piece of 10 km long non-zero dispersion shifted fiber (NZ-DSF) as a Brillouin gain medium to obtain odd-order Brillouin Stokes waves as an output with the line spacing of 0.16 nm (20 GHz) between each two consecutive waves by employing even-order Brillouin Stokes to improve output performance of the laser. With a BP of 15.3 dBm, at least 15 odd-order Brillouin Stokes and anti-Stokes lines are generated. The laser is room temperature stable, tunable over 50 nm wavelength range and has an optical signal to noise ratio of more than 30 dB at 1560 nm region. This Brillouin fiber laser can operate at any wavelength depending on the Brillouin pump (BP) wavelength used.

Effects of pump recycling technique on stimulated Brillouin scattering threshold: a theoretical model

We develop a theoretical model that can be used to predict stimulated Brillouin scattering (SBS) threshold in optical fibers that arises through the effect of Brillouin pump recycling technique. Obtained simulation results from our model are in close agreement with our experimental results. The developed model utilizes single mode optical fiber of different lengths as the Brillouin gain media. For 5-km long single mode fiber, the calculated threshold power for SBS is about 16 mW for conventional technique. This value is reduced to about 8 mW when the residual Brillouin pump is recycled at the end of the fiber. The decrement of SBS threshold is due to longer interaction lengths between Brillouin pump and Stokes wave.

Simple tunable multiwavelength Brillouin/Erbium fiber laser utilizing short-length photonic crystal fiber

We have demonstrated a simple ring cavity tunable multiwavelength Brillouin/Erbium fiber laser (MWBEFL), in which 70 m highly nonlinear photonic crystal fiber (HNL-PCF) is used as the Brillouin gain medium. The fiber laser utilizes recycling mechanism to enhance stimulated Brillouin scattering (SBS). The configuration that consists of only 3 optical components is easy to be integrated and improves the practicality. At the maximum 1480 nm pump power of 110 mW and the Brillouin pump power of 3 dBm, 10 stable output channels with more than 10 dB optical signal to noise ratio (OSNR) and 0.078 nm channel spacing could achieve 10 nm tuning ranges.

Double Brillouin frequency shift through circulation of odd-order Stokes signal

We demonstrate a simple configuration for generating a double Brillouin frequency shift through the circulation of an odd-order Brillouin Stokes signal. It is operated based on cascaded Brillouin scattering in single-mode optical fibers that behave as the Brillouin gain media. A four-port circulator is incorporated into the setup to circulate the odd-order Brillouin Stokes signal in the fiber. It thus initiates a higher order Brillouin Stokes signal, which is double Brillouin frequency downshifted from the input signal. For the 5 km long fiber, the Brillouin pump power at 23 mW gives a clean output spectrum with 30 dB sideband suppression ratio. The output signal is 0.174 nm or approximately 21.7 GHz downshifted from the input signal.

THE COMPARISON NONLINEARITY BEHAVIORS OF PHOTONIC CRYSTAL FIBER BY TWO REDUCED LENGTHS OF BI-EDF IN RING CAVITY

The nonlinearity effects of photonic crystal fiber (PCF) in a ring resonator for different lengths of Bismuth erbium-doped fiber (Bi-EDF) as the Brillouin gain medium is investigated. Bi-EDF (215 cm) itself has high stimulated Brillouin effect at 150 mW that is generated at 1480 nm pump power. The proposed Brillouin fiber laser (BFL) with PCF operates at 1559 nm for 49 cm Bi-EDF, which is upshifted by 0.08 nm from the Brillouin pump with a side-mode suppression ratio more than 12 dB. As a result of using reduced length of PCF and two long Bi-EDF, the BFL is stable at room temperature and compact in this report.

Investigation on the effect of EDFA location in ring cavity Brillouin-Erbium fiber laser

We have investigated the characteristics of Brillouin-Erbium fiber laser (BEFL) with variation of Erbium-doped fiber amplifier (EDFA) locations in a ring cavity configuration. Three possible locations of the EDFA in the laser cavity have been studied. The experimental results show that the location of EDFA plays vital role in determining the output power and the tuning range. Besides the Erbium gain, Brillouin gain also contributes to the performance of the BEFL. By placing the EDFA next to the Brillouin gain medium (dispersion compensating fiber), the Brillouin pump signal is amplified thereby generating higher intensities of Brillouin Stokes line. This efficient process suppresses the free running self-lasing cavity modes from oscillating in cavity as a result of higher Stokes laser power and thus provide a wider tuning range. At the injected Brillouin pump power of 1.6 mW and the maximum 1480 nm pump power of 135 mW, the maximum Stokes laser power of 25.1 mW was measured and a tuning range of 50 nm without any self-lasing cavity modes was obtained.

Bidirectional multiwavelength Brillouin fiber laser generation in a ring cavity

Bidirectional multiwavelength Brillouin fiber laser (BFL) generation is demonstrated using a 25 km long single-mode fiber as a Brillouin gain medium in a ring cavity. Odd-order Brillouin Stokes waves appear in the backward direction whereas Brillouin pump and the even Stokes orders are in the forward direction with the line spacing 0.16 nm (∼20 GHz) between each two consecutive waves in forward and backward directions. In addition, by a combination of the backward and forward outputs, we have a higher number comb generation of a multiwavelength BFL with the line spacing 0.08 nm (∼10 GHz). The proposed configuration can work at any wavelength which is a benefit to the others.

Photonic crystal fibre Brillouin laser based on Bragg grating Fabry–Perot cavity

A photonic crystal fibre Brillouin laser based on fibre Bragg grating Fabry–Perot cavity is presented. A highly nonlinear photonic crystal fibre 25m in length is used as Brillouin gain medium and fibre Bragg grating Fabry–Perot cavity is chosen in order to enhance the laser conversion efficiency and suppress the higher-order Stokes waves. The laser reaches the threshold at input power of 35mW, and the experimental laser conversion efficiency achieves 18% of the input power of 140mW and does not show higher-order Stokes waves. A photonic crystal fibre Brillouin laser with shorter fibre length and lower threshold is experimentally realized.

All‐optical generation of microwave using a photonic crystal fiber Brillouin laser based on Bragg grating Fabry‐Perot cavity

AbstractA novel all‐optical technique for microwave generation using photonic crystal fiber Brillouin laser is presented, and a 9.78‐GHz microwave signal generator based on the Brillouin laser is experimentally realized. The Brillouin laser is based on a fiber Fabry‐Perot cavity with fiber Bragg gratings as reflectors along with 25‐m photonic crystal fiber as Brillouin gain medium. The fiber Bragg gratings are chosen to realize low laser threshold and suppress the higher‐order Stokes waves. Predictions of numerical simulations are compared with experimental results and both are in good agreement with each other. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 809–814, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23221

MICROWAVE/MILLIMETER-WAVE GENERATION USING MULTI-WAVELENGTH PHOTONIC CRYSTAL FIBER BRILLOUIN LASER

An all-optical microwave generation using a multi- wavelength photonic crystal fiber Brillouin laser is presented. A highly nonlinear photonic crystal fiber with the length of 25 m is used as Brillouin gain medium. A Fabry-Perot cavity with two fiber Bragg gratings as reflectors are designed in order to enhance the Brillouin conversion efficiency. The fiber Bragg gratings can be used to selectively excite the jth-order Stokes' wave and suppress other order Stokes' waves. The mechanism for microwave/millimeter- wave generation is theoretically analyzed. In the experiment, both 9.788 GHz and 19.579 GHz microwave signals are achieved through mixing the pump wave with the first-order and the second-order Stokes' waves.

Enhancement of multiwavelength generation in the L-band by using a novel Brillouin-Erbium fiber laser with a passive EDF booster section

We demonstrate a novel scheme to generate multiple wavelengths in the L-band using a Brillouin-Erbium fiber laser. Our scheme utilizes extraneous amplified spontaneous emission in the C-band as a secondary pump source for a passive Erbium-doped fiber gain section along the cavity. The Brillouin gain medium is generated by the 6.7 km long of single mode fiber (SMF-28). We experimentally demonstrate that a total of 28 stable output channels with a spacing of 0.089 nm can be generated using our new scheme. This represents a 33% increase in the number of wavelengths generated compared with conventional schemes.

Experimental Study of Lasing Characteristics of Brillouin/Erbium Optical Fiber Laser

A lasing charactrization of a Brillouin/erbium optical fiber laser (BEFL) is experimentally discussed. In the BEFL, an erbium-doped fiber amplifier (EDFA) is incorporated into the Brillouin laser resonator to enhance small Brillouin gain, which makes the configuration of the Brillouin laser resonator easy and flexible. The experimental results show that the output power of the BEFL has a threshold against the Brillouin pump power, and above the Brillouin threshold, the output power increases linearly with the EDFA pump'power. The BEFL threshold decreases with increasing the length of the optical fiber in the laser resonator used as a Brillouin gain medium. The BEFL oscillates in a stable single longitudinal mode because the bandwidth of the Brillouin gain profile is very narrow (∼ 30 MHz). The relative intensity noise (RIN) and the spectral lineshape were measured. The noise floor level decreases with increasing the EDFA pump power, and the full-width at half maximum of the BEFL was measured to be about 8 kHz.

Stabilized single-frequency stimulated Brillouin fiber ring laser

The detailed behavior of the cw stimulated Brillouin fiber laser has been studied by using a narrow-linewidth cw pump argon laser at 5145 A and an 83-m fiber ring cavity. By stabilizing the fiber cavity, we achieved stable single-frequency Brillouin-laser output with a linewidth determined primarily by the 100-kHz modulation used in the feedback system. Lasing threshold for the 4.5-microm-core fiber used was observed at a pump power of 77 mW, and the maximum Brillouin output was 13 mW for a pump of 320 mW. The Brillouin gain medium was shown to exhibit homogeneouslike behavior.