Multiwavelength L-band fiber laser with bismuth-oxide EDF and photonic crystal fiber

A multiwavelength laser comb using a bismuth-based erbium-doped fiber and 50 m photonic crystal fiber is demonstrated in a ring cavity configuration. The fiber laser is solely pumped by a single 1455 nm Raman pump laser to exploit its higher power delivery compared to that of a single-mode laser diode pump. At 264 mW Raman pump power and 1 mW Brillouin pump power, 38 output channels in the L-band have been realized with an optical signal-to-noise ratio above 15 dB and a Stokes line spacing of 0.08 nm. The laser exhibits a tuning range of 12 nm and produces stable Stokes lines across the tuning range between Brillouin pump wavelengths of 1603 nm and 1615 nm.     

C-band continuously tunable lasers using tunable fiber Bragg gratings

We report the development of a ring tunable fiber laser based on tunable fiber Bragg gratings (TFBG) integrated with an optical circulator. The TFBG is embedded inside a 3-piont bending device for wavelength tuning. The tunable laser operating in the C-band has power variation, tuning resolution, tuning range and laser line width of ±0.5 dB, 0.5 nm, 25.0 nm and less than 0.05 nm, respectively. As 40 mW of pump power is used, the ring tunable laser has a side mode suppression ratio of 60 dB and a power conversion efficiency of 25%. These specifications ensure the high-quality operation of a tunable laser.     

An efficient S-band brillouin erbium fiber laser with additional EDFA

A short wavelength band brillouin–erbium fiber laser (S-band BEFL) with enhanced characteristics is demonstrated using an additional erbium-doped fiber amplifier (EDFA) in the sub-loop of the laser system. Compared with the conventional BEFL without the additional EDFA, the enhanced BEFL has improved the number of channels as well as the flatness of the brillouin Stoke's peak power. By incorporating a double-pass EDFA, a stable output laser comb up to 8 channels was obtained at 1503 nm wavelength region with peak power variation for the first three Stokes is reduced from 30.9 to 5.4 dB. The incorporation of additional EDFA also increases the tuning range of the BEFL, which the maximum tuning range of 1.8 nm was obtained with the single-pass scheme. The S-band BEFL has constant spacing of 0.09 nm or 11 GHz, which has a potential application in dense wavelength division multiplexed system.     

间隔可调多波长光纤激光器的实验研究

半导体光放大器(SOA)的非均匀加宽特性对产生多波长激光非常有利。本文对两段式立奥-萨尼亚克(Lyot-Sagnac)滤波器进行了详细的理论分析,实现了一种基于半导体光放大器的新型多波长光纤激光器。它利用立奥-萨尼亚克滤波器的波长选择性,在室温下得到了约18个具有30 dB信噪比的多波长激光输出。波长范围1556~1577 nm。通过调节立奥-萨尼亚克环内的偏振控制器,多波长激光的波长间隔可在两种国际电信联盟(ITU)标准波长间隔(0.4 nm和0.8 nm)间选择。这种构型的光纤激光器具有稳定性好、波长间隔可控、信噪比高等优点。     

Versatile Raman fiber laser for sodium laser guide star

Robust high‐power narrow‐linewidth lasers at 589 nm are required for sodium laser guide star adaptive optics in astronomy. A high‐power 589 nm laser based on Raman fiber amplifier is reported here, which works in both continuous‐wave and pulsed formats. In the continuous‐wave case, the laser produces more than 50 W output. In the pulsed case, the same laser produces square‐shaped pulses with tunable repetition rate (500 Hz to 10 kHz) and duration (1 ms to 30 μs). The peak power is as high as 84 W and remains constant during the tuning. The laser also emits an adjustable sideband at 1.71 GHz away from the main laser frequency for better sodium excitation. The versatility of the laser offers much flexibility in laser guide star application.     

Dual-core ytterbium fiber amplifier for high-power 1060 nm swept source multichannel optical coherence tomography imaging

A novel (to our knowledge) dual-core ytterbium (Yb(3+)) doped fiber, as an optically pumped amplifier, boosts the output power from a 1060 nm swept source laser beyond 250 mW, while providing a wavelength tuning range of 93 nm, for optical coherence tomography (OCT) imaging. The design of the dual-core Yb-doped fiber amplifier and its multiple wavelength optical pumping scheme to optimize output bandwidth are discussed. Use of the dual-core fiber amplifier showed no appreciable degradation to the coherence length of the seed laser. The signal intensity improvement of this amplifier is demonstrated on a multichannel in vivo OCT imaging system at 1060 nm.     

Widely tunable compact erbium-doped fiber ring laser for fiber-optic sensing applications

A compact erbium-doped ring-shaped fiber laser suitable for fiber-optic sensing applications has been developed. The fiber laser utilized a tunable fiber Fabry–Perot filter as the tuning element and had a moderate milli-Watt level power output over almost the whole tuning range from 1530 to 1595 nm with a power fluctuation of 0.15 dB. High repetition rate scanning of laser operation over the whole tuning range was achieved at rates of up to 200 Hz. Moreover, the performance of the ring-shaped fiber laser configured with a high-concentration erbium-doped fiber was investigated for its larger wavelength tunability of over 100 nm. Output power characteristics of this ring-shaped fiber laser were also investigated when it worked in a scanning mode. A distorted power wavelength dependence, as well as some pulsing phenomenon were observed in scanning mode.     

An energy-efficient tie-type architecture for stable and wavelength-tunable SOA-based fiber laser

A new and energy-efficient tie-type architecture for stable and wavelength-tunable semiconductor optical amplifier (SOA)-based fiber ring laser is proposed and experimentally investigated. Here, the tie-type laser configuration is constructed by two Sagnac fiber loops. The proposed laser also can extend the lasing wavelength to longer wavelength (L-band) even only the C-band SOA is used. The proposed tie-type architecture has >5 dB higher output optical power at bias current of 80 mA when compared with the single ring SOA-based fiber laser. In this measurement, the output power, wavelength tuning range, side-mode suppression ratio (SMSR) and output stability of proposed fiber laser have also been analyzed and discussed.     

Tunable pulses from below 300 to 970 nm with durations down to 14 fs based on a 2 MHz ytterbium-doped fiber system

A noncollinearly phase-matched optical parametric amplifier pumped by a commercial 2 MHz fiber laser is presented and discussed. The pump system allows the direct generation of a seed continuum from a sapphire plate. Clean pulses with up to 860 nJ energy and down to 14 fs pulse length can be obtained over a fundamental tuning range from 620 to 970 nm. Conversion by second- and third-harmonic generation as well as sum frequency mixing results in an extended tuning range down to well below 300 nm.     

Tunable dual-wavelength erbium-doped fiber ring laser covering both C-band and L-band for high-speed communications

A simple, continuously tunable dual-wavelength erbium-doped fiber ring laser (TDEDFL) structure for applications in high-speed communication systems is proposed and experimentally demonstrated. The dual-wavelength tuning range is 58 nm covering both the C-band and L-band from 1547 to 1605 nm. We can not only obtain a 45% improvement over previously reported tuning ranges, but also tune the wavelength of each lasing output independently. The power equalization of the dual-wavelength outputs is less than 1.5 dB. We obtain extremely stable power variation and wavelength fluctuation at room temperature. Using this fiber laser, a 10-Gb/s data transmission over a 25-km single-mode fiber (SMF) can be made available with a power penalty of 0.5 dB is demonstrated with this laser.     

Multiple Parameters Optical Sensing Using Fiber Ring Laser Based on Fiber Bragg Gratings and 1064 nm Semiconductor Optical Amplifier

Optics and Spectroscopy - In this paper, a semiconductor optical amplifier (SOA) based 1064 nm fiber ring laser with 63.56 dB optical signal-to-noise ratio (OSNR) is demonstrated. The...     

Broadband Brillouin slow light with multiple-longitudinal-mode,tunable pump

We propose and demonstrate broadband Brillouin slow light using a multiple-longitudinal-mode tunable fiber laser as Brillouin pump. A tunable broadband Brillouin pump with a tuning range from 1 520 to 1 555 nm is generated using a fiber ring laser with a semiconductor optical amplifier (SOA) as its gain medium. The pump spectrum consists of a large number of longitudinal modes separated by 6 MHz. The 3-dB bandwidth is about 11.5 GHz, and its fluctuation is less than 100 MHz within the tuning range. An 8-Gb/s data signal can be delayed by up to 83.0 ps (bit error rate < 10 9) at 17-dBm pump power.     

Experimental study on tandem pumped fiber amplifier

We present the experimental results of a 1083 nm fiber amplifier tandem pumped by 1030 nm fiber laser. The output characteristics of the tandem pumped amplifier with cladding-pump and core-pump schemes are both investigated. The 1083 nm signal laser has not been efficiently amplified when cladding-pumped by 1030 nm laser for the weak absorption of the gain fiber. The core-pump scheme works well with the amplifier. The output properties with different gain fiber length are experimentally investigated. The maximum output power is 2.4 W with power conversion efficiency of 60%.     

Eleven-wavelength switchable fiber ring laser with a dispersion compensation fiber and a delayed interferometer

We demonstrate a fiber ring laser with a dispersion compensation fiber (DCF) and a delayed interferometer (DI) with temperature control, which is able to switch eleven wavelengths one by one. In ring cavity, DCF supplies different effective cavity lengths for different wavelengths, DI generates a wavelength comb corresponding to the ITU grid, a flat-gain erbium-doped fiber amplifier (EDFA) provides uniform gain for each lasting wavelength, and a semiconductor optical amplifier (SOA) not only acts as active modulator, but also alleviates homogeneous broadening effect of EDFA. Stable pulse trains with a pulsewidth about 40 ps at 10 GHz have been obtained by injecting external optical control signals into the laser. Wavelength switching process among eleven wavelengths is achieved by merely tuning an intracavity optical delay line.     

High-speed wavelength-swept semiconductor laser with a polygon-scanner-based wavelength filter

Ultrahigh-speed tuning of an extended-cavity semiconductor laser is demonstrated. The laser resonator comprises a unidirectional fiber-optic ring, a semiconductor optical amplifier as the gain medium, and a novel scanning filter based on a polygonal scanner. Variable tuning rates up to 1150 nm/ms (15.7-kHz repetition frequency) are demonstrated over a 70-nm wavelength span centered at 1.32 microm. This tuning rate is more than an order of magnitude faster than previously demonstrated and is facilitated in part by self-frequency shifting in the semiconductor optical amplifier. The instantaneous linewidth of the source is <0.1 nm for 9-mW cw output power and a low spontaneous-emission background of -80 dB.     

Directivity influence of signals propagation through EDFA gain medium of Brillouin-erbium fiber laser

We experimentally demonstrate a multiwavelength Brillouin-erbium fiber laser in two configurations; uni-directional and bi-directional propagation of Brillouin pump and Brillouin Stokes signals through an Erbium-doped fiber gain. The influence of these configurations on the performance of the output parameters in terms of lasing threshold, output channel generation and tuning range of the generated output channels are investigated. We discovered that there is a trade-off between these two fiber laser configurations. The uni-directional amplifier configuration provides greater tuning range of 46.8 nm against 23 nm at maximum Brillouin pump power of 2 mW and 1480-nm pump power of 130 mW. On the other hand, the bi-directional amplifier configuration provides 13 output channels against 6 output channels obtained from the uni-directional amplifier configuration at the same pumping powers. Nevertheless, the bi-directional amplifier configuration requires much lower pump power to initiate lasing.     

Monolithic QW laser beam steering and wavelength tunability

We demonstrate a monolithic tunable laser on a QW structure by integrating an optical beam steering section with an area-selectively intermixed QW gain section. Wavelength switching is achieved by steering the laser beam over an optical gain medium that consists of two laterally adjacent quantum well regions selectively intermixed to varying extents. The device output had a total of 10 nm wavelength tuning that was controlled by injecting separate electrical current values to each of the steering contacts and the amplifier contact.     

Tunable, μs-pulsed ytterbium fiber laser system with a linewidth below 2.7 GHz

We report on a widely tunable, pulsed laser system with narrow spectral linewidth based on a continuous wave ytterbium fiber oscillator, a pulse shaper and a power amplifier stage. The system is tunable from 1055 nm to 1085 nm and provides a maximum pulse energy of 155 μJ with a pulse duration of 1-5 μs. The linewidth is less than 2.7 GHz over the whole tuning range.     

Wavelength tunable high power laser using a double-clad Er:Yb doped fiber

We experimentally demonstrated a stable, wavelength-tunable fiber laser using a polarization-maintaining, double-clad Er:Yb doped fiber amplifier in the cavity. The output wavelength is tunable over the range from 1535 to 1567 nm using a fixed grating and the dichroic mirror placed on a rotational mount; under rotation of the dichroic mirror the tuning ratio of 50 nm/deg was found. We studied the wavelength tuning range dependence on the amplifier fiber length and achieved a maximal output power of 850 mW. This configuration can be Q-switched for high peak power and its narrow bandwidth is suitable for nonlinear optics applications, such as parametric teraherthz generator.     

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.