Z. Jusoh

Double-clad thulium/ytterbium co-doped octagonal-shaped fibre for fibre laser applications

We investigate the lasing performance of a new double-clad thulium/ytterbium co-doped octagonal-shaped fibre, basing on a cladding pump technique. The fibre is fabricated with the aid of a modified chemical vapour deposition combined with a solution doping technique. It is characterized by the Tm3+ and Yb3+-cladding absorptions equal to 0.325 and 3.3 dB/m respectively at 790 and 976 nm. A triple-wavelength fibre laser operating at 1914.5, 1934.7 and 1953.6 nm is built that uses a 5 m long fibre in a ring configuration as a gain medium. With the fibre as long as 15 m, the ring laser produces the highest output power of 21.9 mW at the pump power of 3600 mW, with the lowest threshold pump power being equal to 1000 mW. When operating at 1961.4 nm, the maximal efficiency of 0.88 per cent is achieved for the gain medium length fixed at 10 m. We also demonstrate a Q-switched thulium/ytterbium-doped fibre laser that operates at 1977.5 nm and utilizes multi-walled carbon nanotubes as a gain medium. By varying the multimode 905 nm pump power from 1591.3 to 2261.5 mW, one can increase the pulse repetition rate from 18.8 to 50.6 kHz, while the pulse width then decreases from 8.6 to 1.0 mu S. The maximum pulse energy 5.71 nJ is obtained at the pump power 2100 mW.

An Enhanced Bismuth-Based Brillouin/Erbium Fiber Laser with Linear Cavity Configuration

Abstract A multi-wavelength Brillouin/erbium-doped fiber laser (BEFL) which operates in 1594 nm region is demonstrated using a 215 cm long Bismuth-based EDF and SMF. Two optical circulators were used at the output ends of the system to form a linear cavity to produce a cascaded Brillouin Stokes and anti-Stokes. A stable output laser comb of more than 20 lines was obtained with a spacing of approximately 0.089 nm at a Brillouin pump power of 4 dBm and two 1,480-nm pumps at powers of 100 mW. The number of lines is relatively higher compared with the ring cavity BEFL.

Dual-wavelength erbium-ytterbium co-doped fibre laser operating at 1064 and 1534 nm

We demonstrate a simple erbium-ytterbium co-doped fibre laser with dual-wavelength output, which operates at 1064 and 1534 nm using a single gain medium. The laser operates on a recently developed erbium-ytterbium doped fibre (EYDF) with the erbium and ytterbium ion concentrations of 1000 and 1500 ppm respectively, in conjunction with a linear cavity setup based on two fibre Bragg gratings. By pumping a 5 m long EYDF with a 980 nm laser diode, simultaneous generation at 1064 and 1534 nm is reached, with the corresponding peak powers of 3.4 and -8.3 dBm. The lasing thresholds are 40 and 80 mW respectively for 1064 and 1534 nm.

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.

Nanosecond Pulse Generation Using the Stimulated Brillouin Scattering Effect in a Photonic Crystal Fiber

A nanosecond pulsed laser is demonstrated using the stimulated Brillouin scattering (SBS) effect in a nonlinear photonic crystal fiber (PCF). The Brillouin fiber laser (BFL) uses a 50-m-long PCF in a simple ring cavity to generate a self-starting pulse as the Brillouin power reaches 16.5 dBm based on the relaxation oscillation technique. The BFL generates a pulse train with repetition rates of 2.7 MHz and 5.4 MHz depending on the BP power. The pulse width of the laser is obtained to be 190 ns at the BP power of 16.5 dBm and is maintained at around 72 ns as the pump power is set within 17.7 dBm and 18.5 dBm. The maximum pulse energy of 20 nJ is obtained at BP power of 17.4 dBm. This SBS based pulse laser is fairly stable at room temperature.

Cadmium Selenide Polymer Microfiber Saturable Absorber for Q-Switched Fiber Laser Applications

We demonstrate the generation of a Q-switching pulse train in an erbium-doped fiber laser (EDFL) cavity using a newly developed cadmium selenide (CdSe) based saturable absorber (SA). The SA is obtained by embedding CdSe nanomaterials into a polymethyl methacrylate (PMMA) microfiber. It is incorporated into an EDFL cavity to generate a Q-switched laser operating at 1533.6 nm. The repetition rates of the produced pulse train are tunable within 37–64 kHz as the pump power is varied from 34 mW to 74 mW. The corresponding pulse width reduces from 7.96 μs to 4.84 μs, and the maximum pulse energy of 1.16 nJ is obtained at the pump power of 74 mW.

Mode-locked fiber laser with a manganese-doped cadmium selenide saturable absorber

We demonstrate the generation of mode-locked pulses in an erbium-doped fiber laser (EDFL) by using a new manganese-doped cadmium selenide quantum-dots-based saturable absorber. The laser produces a soliton pulse train operating at 1561.1 nm with a repetition rate of 1 MHz, as the pump power is varied from 113 to 250 mW. At the maximum pump power, we obtain the pulse duration of 459 ns with a signal-to-noise ratio of 50 dB.