A short pulse self-starting mode-lock fiber laser with femtosecond pulse width and high repetition rates is demonstrated. The oscillator features linearly cavity employing WDM system with a piece of Yb doped fiber. Semiconductor saturable absorber mirror (SESAM), with modulation depth of 30% and relaxation time of 4 ps, is employed. Two chirped fiber Bragg gratings are adopted. One FBG is placed in the cavity, with wide reflection near 1053nm. It compensates for the residual dispersion of the oscillator cavity elements and serves as an output coupler for the oscillator. The other FBG is placed out of the cavity to compress the pulse width further more. The length of laser cavity is around 10m. This modelock laser can self-start. Pulses as short as 225 fs pulse widths at repetition rates of 20 MHz are generated, with average output power is about 5mW. As all of the optical fiber components are small or bendable, the size of this laser is as tiny as Φ60mm×15mm.This femtosecond mode-lock all fiber laser affords a compact, novel and high-efficiency approach as seed source in the FrontEnd in inertial confinement fusion (ICF) laser illumination schemes.
In recent years, the power level of laser outputting from twins fiber, being of pump unit fiber and gain unit fiber, is continuing rising. However, little report is focused on the pump coupling efficiency and thermal management on account of the distinctive waveguide of twins fiber. In this paper, the experiment study was launched on pump coupling efficiency and thermal management based on our previous work. To facilitate observing, two waveguides were designed as “cycle pump unit + octagonal gain unit” and “cycle pump unit + cycle gain unit”, while both gain units contained no doping core and the claddings were all 125 um approximately. It indicated that the pump power proportion between pump unit and gain unit was gradually changing with increasing of fiber length when the fiber was pumped from only one side of pump unit. The dynamic balance of pump power proportion could be obtained as the length of “cycle pump unit + octagonal gain unit” twins fiber is more than 4 m. By contrast, the balance point appeared earlier for “cycle pump unit + cycle gain unit” twins fiber before the length was up to 4 m. Further, the laser experiment was executed by using typical twins fiber that was consisted of one octagonal gain unit, containing Ytterbium (Yb) doped fiber core, and cycle pump unit. When the power was pumped into the fiber from the pump unit, the temperature of pumping point was obviously lower than conventional double cladding active fiber.
In this paper, a practical single-frequency high-repetition linearly-polarized eye-safe all-fiber laser with constant peak power is demonstrated. It is based on master-oscillator power amplifier (MOPA) system. A distributed feedback laser diode simulating at 1550nm with narrow linewidth of 2.3 kHz is employed as the seed source. It is modulated to a pulse laser with high repetition of 20 kHz and peak power of 10mW by an acousto-optic modulator (AOM). The pulse width is tunable between 100ns to 400ns. Two-stage cascade amplifier is established, which consists of a pre-amplifier and a power-amplifier. Amplified spontaneous emission (ASE) and stimulated billion scattering are well suppressed by special management. The output peak power of 30W is obtained, which has nearly diffraction-limited beam quality. It operates in linewidth of 1.2MHz, polarization-extinction ratio (PER) of 25dB and signal-to-noise ratio (SNR) of more than 40dB. Gain of the whole amplifier achieves nearly 35dB. Furthermore, an embedded control system (ECS) based on the WinCE operating system (OS) and the chip of S3C2440 is proposed. This control system based on closed-loop feedback technology makes the peak power keeping constant even the pulse width tunable, which is convenient for the end user of the radar. This robust portable laser is remarkable and fulfills the desire of coherent detection excellently.
In the paper, we reported a single-frequency(SF), single-mode(SM), linear-polarized ytterbium-doped all-fiber master
oscillator power amplifier (MOPA) system consisting of two stage amplifier which could be used in coherent detection.
With a pump power of 17.5W at 976nm, the system emitted up to 12.7 W of single-frequency radiation at a wavelength
of 1064 nm with the polarization-extinction ratio (PER) more than 35dB and signal-to-noise ratio (SNR) more than 40dB.
The final-stage amplifier operated with a high conversion efficiency of 73% and the gain of the whole amplifier achieved
31 dB, it has nearly diffraction-limited beam quality.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.