Mohammadreza Rezazadeh Shirazi

Linear cavity Brillouin fiber laser with improved characteristics.

A configuration for linear cavity Brillouin fiber laser (BFL) generation is demonstrated using a standard single-mode fiber, two optical circulators, a 3 dB coupler, and a 95/5 coupler to allow high efficiency. With a Brillouin pump (BP) power of 13 dBm, the laser peak power is 12.3 dB higher than a conventional linear cavity BFL at an upshifted wavelength of 0.086 nm from the BP wavelength. In addition, it is revealed that the BFL peak power can be higher than the transmitted BP peak power when the BP power exceeds the second Brillouin Stokes threshold power.

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.

Effects of different Raman pumping schemes on stimulated Brillouin scattering in a linear cavity

The effects of backward, forward, and bidirectional Raman pumping schemes on stimulated Brillouin scattering (SBS) is investigated in this study. By using a linear cavity, we utilize residual Brillouin pump (BP) and Raman pump (RP) power after each transmission through a 25 km single-mode fiber (SMF) used as a gain medium. The SBS threshold power is reduced in the forward, backward, and bidirectional Raman pumping schemes by 2.5, 1.75, and 2.75 dB, respectively when the 1480 nm RP power is fixed at 150 mW and the BP wavelength is 1580 nm. Surprisingly, it is revealed that the SBS threshold reduction depends strongly and solely on Raman gain and it is independent of the Raman pumping schemes. In addition, the effect of Raman amplification on SBS is more effective at the SBS threshold, especially in the bidirectional and forward schemes.

A linear cavity brillouin/bismuth-based erbium-doped fiber laser with enhanced characteristics

A new linear cavity BEFL configuration for increased Stokes-line generation is proposed and demonstrated utilizing a 2 × 2 coupler at the end of the linear cavity. The proposed linear cavity is able to generate up to 33 Stokes lines in the 1590-nm region at a channel spacing of 0.089 nm. The Stokes lines are generated at a BP power of 4 dBm and a 1480-nm pump power of 100 mW. The number of Stokes generated by the proposed BELF is higher compared to conventional BEFL configurations in which the 2 × 2 coupler is placed in the middle of the linear cavity. The number of Stokes lines generated is observed to depend on the 1480-nm pump power as well as the operating wavelength region, which must be as close as possible to the lasing bandwidth of the free-running BEFL. The proposed multiwavelength BEFL is able to operate stably at room temperatures and is also compact due to the use of a 215-cm bismuth-based EDF as the linear gain medium.

Multi-wavelength Brillouin Raman erbium-doped fiber laser generation in a linear cavity

A multi-wavelength Brillouin Raman erbium-doped fiber laser is proposed and demonstrated. The setup uses a 7.7 km dispersion compensating fiber simultaneously as the Brillouin and Raman nonlinear gain media and operates in conjunction with a 3 m erbium-doped fiber as the linear gain medium. At a Brillouin pump (BP) wavelength of 1530 nm, where Raman and erbium gains overlap each other, 34 Brillouin Stokes lines having line spacing of 0.075 nm are created by using a Raman pump power of only 24.1 dBm, an erbium pump power of about 22.1 dBm, and a BP power of 6.5 dBm in the proposed linear cavity. The system is highly efficient and is able to generate many comparable peak-power lines at a low pump power.

Multi-wavelength Brillouin–Raman fiber laser generation assisted by multiple four-wave mixing processes in a ring cavity

A multi-wavelength Brillouin?Raman fiber laser (MBRFL) is generated by using a 7.7?km long dispersion compensating fiber which acts as both the Brillouin and Raman gain media. The MBRFL is pumped at 16?dBm with two Raman pumps at 125?mW. Eleven Stokes and anti-Stokes lines are generated with a line spacing of about 0.155?nm (?19.86?GHz) without any forward line reflection. By combining the backward and forward outputs, more lines can be generated, with narrower line spacings of about 0.077?nm (?9.93?GHz). The number of lines can be increased by having higher Brillouin and Raman pump powers. Since Raman amplification can be arranged at any wavelength region, the MBRFL can be obtained at any wavelength as long as all of the equipment and components are prepared in the proposed operational wavelength region.

MULTIWAVELENGTH SOURCE USING A BRILLOUIN FIBER LASER

A multiwavelength laser operating on the basis of stimulated Brillouin scattering (SBS) is demonstrated in a single mode fiber (SMF) coupled with a feedback loop and an optical circulator. Ten simultaneous Stokes and anti-Stokes lines are obtained with a line spacing of either 0.08 or 0.16 nm at a Brillouin pump (BP) power of 14 dBm. The use of a 50/50 fused coupler gives the highest number of lines at a Stokes power of approximately 8 dBm. The anti-Stokes lines are generated by four-wave mixing and bidirectional operation of the system. This Brillouin fiber laser (BFL) is capable of operating at any wavelength, depending completely on the BP wavelength. Due to the built-in feedback mechanism, its operation is free from the need for any additional active linear gain medium, such as erbium-doped fibers used in a Brillouin erbium fiber laser. Further, the SMF can in principle be replaced with a highly nonlinear waveguide, such as a photonic crystal waveguide, to make a compact multiwavelength BFL.

Multi-wavelength fiber laser generation by using optical wavelength conversion

A multi-wavelength fiber laser source is proposed and demonstrated by using simple, efficient wavelength conversion of a multi-wavelength Brillouin fiber laser (MBFL) assisted by four-wave mixing (FWM) processes. The MBFL is generated by emitting a Brillouin pump (BP) at the wavelength 1530 nm into a dispersion compensating fiber (DCF) of length 7.7 km in a ring cavity. By using the MBFL and a tunable laser source (TLS) as a FWM pump, both amplified through an erbium-doped amplifier and injected into a 100 m long highly nonlinear fiber (HNLF), two bundles of multi-wavelength fiber lasers are operated by degenerate FWM processes. When the TLS is set in the L band wavelength region, the two bundles of multi-wavelength fiber lasers are generated simultaneously in the S and U band wavelength regions.