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In this paper, we propose and demonstrate a dual wavelength fibre laser (DWFL) based on the use of an inhomogeneously-broadened semiconductor optical amplifier (SOA) gain medium as well as two arrayed waveguide gratings (AWGs) together with two optical channel selectors (OCSs) and a broadband fibre Bragg grating (FBG) to generate dual wavelength output at variable channel spacings. The widest spacing obtained from the DWFL is 12.21 nm, while the narrowest spacing is 1.16 nm. The DWFL has good stability with only minor power fluctuations of less than 2 dB and a side mode suppression ratio (SMSR) of approximately 38.5 dB with fluctuations of less than 0.5 dB. [ABSTRACT FROM AUTHOR]

This paper demonstrates the use of a tapered fibre in generating a highly stable and tunable dual-wavelength fibre laser. By unique arrangement of polarization controller, adjustable spacing range between 0.94 and 3.32 nm and side mode suppression ratio (SMSR) up to 50 dB were recorded. The results were achieved at laser pump power of 94.7 mW. The inter-modal interference is achieved through the use of a non-adiabatic tapered fibre, made by a systematic flame brushing technique. The tapered fibre suppresses the mode competition in the 3-m erbium-doped fibre (EDF) gain medium. Over 60 min, the laser exhibited very high stability with acceptable peak power and SMSR. The proposed EDF laser operates from 1556.71 to 1562.13 nm range. [ABSTRACT FROM PUBLISHER]

In this paper, we propose and demonstrate a cost-effective wavelength converter utilising a highly nonlinear fibre (HNLF) and a tunable dual-wavelength fibre laser as the pump source. The proposed system uses only the pump source and a signal probe to generate a partially degenerate four-wave mixing (FWM) effect. An FWM conversion efficiency of -12 dB is obtained at pump and signal powers at +13.3 dBm and +5 dBm, respectively, and it is predicted that a higher conversion efficiency is possible if a high power dual-wavelength fibre laser source is used. [ABSTRACT FROM AUTHOR]

The generation of short, intense, mid-infrared laser pulses allows for the exploration of atom-laser interactions deep in the tunnelling regime as well as providing the ability to explore scaled interactions. In this paper we present recent experimental and theoretical results for this largely unexplored parameter space. [ABSTRACT FROM AUTHOR]

A dual-wavelength self-Q-switched operation of Nd:GYSGG laser with different output couplers is proposed and demonstrated. In self-Q-switched operation, two laser lines between 1056.86 nm and 1060.23 nm were found. Under the pump power of 4 W, the shortest pulse width of 2.02 μs was obtained with a maximum average output power of 565 mW and the optical conversion efficiency of 14.13%. The pulse repetition rate and single pulse energy were 50.2 kHz and 11.25 μJ, respectively. The system is very stable and suitable for generation of multi-wavelength pulses. [ABSTRACT FROM AUTHOR]

A multi-wavelength laser source is demonstrated with a semiconductor optical amplifier (SOA) as a gain medium. A multi-wavelength comb with equal spacing is achieved due to Fabry-Perot modes of the SOA which oscillates in the ring cavity. A 100 m long photonics crystal fiber (PCF) is inserted in the ring cavity to provide a nonlinear gain by four-wave mixing (FWM) so that the output comb spectrum can be greatly broadened and flattened. The stability of the ring laser is also increased due to the efficient FWM phenomenon occurring in the PCF. The SOA-based laser can generate 35 lasing lines with equal spacing of 0.28 nm and extinction ratios of more than 30 dB at room temperature. The number of channels of the multi-wavelength laser can be controlled flexibly by changing the ratio of the coupler used in the ring cavity configuration as well as controlling the polarization state of the oscillating laser. [ABSTRACT FROM AUTHOR]

A new scheme to generate isolated attosecond pulses is presented that involves the use of a laser field and of a unipolar field. The laser field has a pulse of intensity I = 1.5×1014 W cm-2 and wavelength λ = 820 nm. The unipolar pulse is an asymmetric pulse consisting of a sharp peak, lasting approximately half a laser period, i.e. nearly 1.4 fs, followed by a long and shallow tail. We show that on combining these two fields, it is possible to generate isolated attosecond pulses as short as 1/10 of a laser period, i.e. approximately 270 as. Moreover, it is argued that this scheme is robust either against small variations of the laser envelope, or against small changes in the delay between the laser pump and the unipolar pulse. [ABSTRACT FROM AUTHOR]

We present quantitative phase images of cells and other microscopic samples, using three-wavelength optical phase unwrapping. Laser diodes and a ring dye laser are used in a standard four-frame phase shifting interferometer to obtain phase profiles with larger beat wavelengths, thus removing 2π ambiguities without increasing phase noise. The effectiveness of three-wavelength optical phase unwrapping with both laser diodes and a ring dye laser as light sources is demonstrated. [ABSTRACT FROM AUTHOR]

We propose and demonstrate a novel switchable multiwavelength erbium-doped fiber laser with a overlapping linear cavity, which is formed by a dual-section Lyot-Sagnac filter and three fiber Bragg gratings (FBGs). Taking advantage of the high extinction of the Lyot-Sagnac filter, independent controlling of the different wavelength losses and the spatial hole burning in the overlapping linear cavities, with this structure we realize stable switchable multiwavelength laser emission at room temperature. An output signal to background noise ratio of ∼43 dB and less than 3 dB fluctuation on output power were observed for all wavelength switching cases. [ABSTRACT FROM AUTHOR]

We demonstrate a simple method to control the spectrum and to generate synchronized dual-wavelength pulses in a mode-locked Ti:sapphire laser by adjusting the cavity dispersion, without involving more complicated coupled cavities or two-slit systems. We explore the tunability range of our system, and demonstrate the possibility of obtaining pairs of synchronized pulses with adjustable frequency difference. Furthermore, we use this laser to obtain tri-wavelength pulses in the blue range of the spectrum, via second-order nonlinear processes in an LBO crystal. This system may become a useful tool for femtosecond coherent anti-Stokes Raman spectroscopy, and other applications as well. [ABSTRACT FROM AUTHOR]