国产啁啾布拉格光纤光栅在飞秒激光系统中的应用

利用自行研制的啁啾布拉格光纤光栅(CFBG)刻写系统完成CFBG样品制作,成功应用于光纤锁模振荡器和啁啾脉冲放大(CPA)系统中。振荡器可输出19.4 nm带宽、18 mW平均功率激光,并可压缩至143 fs,经时域展宽、功率放大、时域压缩后,脉冲宽度可至264 fs。实验结果初步证明了国产CFBG在飞秒激光系统应用的可行性。     

Incorporate, switchable dual-wavelength fiber laser with Bragg gratings written in a polarization-maintaining erbium-doped fiber

A stable, incorporate and switchable dual-wavelength fiber laser with two fiber Bragg gratings written in a photosensitive and polarization-maintaining erbium-doped fiber directly, that is, without splices in the laser cavity, is proposed and demonstrated. Simultaneous dual-wavelength oscillation is achieved at room temperature with a wavelength spacing of 0.343 nm. The power fluctuation and wavelength shift of single-wavelength oscillations are measured to be less than 0.24 dB and 0.013 nm over 2 h. The wavelength switchability between single- and dual-wavelength oscillations is realized by altering the voltage upon the electrostrictive ceramic actuator.     

All-fiber actively Q-switched fiber laser tuned by a pair of temperature controlled fiber Bragg gratings

We report an all-fiber actively Q-switched erbium-doped fiber laser, where the linear laser cavity mirrors are composed of two fiber Bragg gratings (FBGs). The laser oscillation wavelength could be tuned by this pair of temperature controlled FBGs. The Q-switching is achieved by an all-fiber phase modulation device. Using this system, we could obtain stable Q-switched laser pulses output, which could be optimized by tuning the reflection wavelengths of the two FBGs to be adjacent to each other. Instead of being modulated by the FBG filter in high-speed oscillation, this fiber laser system is operating in the Q-switched regime using an all-fiber phase modulator, producing a more stable laser output spectrum.     

Tunable erbium doped fiber ring laser using fiber Bragg grating-assisted add-drop filter

A stable and low costless tunable erbium doped fiber ring laser using fiber Bragg grating-assisted add-drop filter is proposed and demonstrated. A stable laser output is obtained with a 4 nm tuning range. The power fluctuation, full-width at half maximum and SMSR are measured to be less than 0.50 dB, smaller than 0.015 nm and better than 55 dB in this tuning range.     

SOA-based multi-wavelength laser using fiber Bragg gratings

We propose and experimentally demonstrate a triple-wavelength fiber ring laser using a semiconductor optical amplifier (SOA) in conjunction with a series of fiber Bragg gratings (FBGs). The three channels operate at 1554.4, 1555.3, and 1556.1 nm with a peak power above ?25 dBm and optical signal-to-noise (OSNR) above 30 dB at SOA drive current of 350 mA under the room temperature. The proposed laser configuration has the advantages of a simple and compact structure, multi-wavelength operation and the system can be upgraded to generate more wavelengths by increasing the number of FBG used.     

Tunable writing Tm-doped intracore fiber Bragg gratings using 800 nm femtosecond laser and phase mask

The intracore fiber Bragg gratings (FBGs) were successfully written into the non-photosensitive multi-mode Tm-doped fiber core by the 800 nm fs laser and a phase mask. Using the varied focal length lens, the tunable writing was realized, and the tunable wavelength band was over 84 nm. A geometrical optics imaging model and numerical calculation were described to explain the tunable writing mechanism. The interference modulation intensity characteristics were also theoretically investigated considering the beam incident angle variation. Based on the intracore FBGs, the all-fiber Tm-doped fiber laser had a maximal output power of 15.8 W with a slope efficiency of 30% and threshold of 5.1 W.     

Switchable dual-wavelength Erbium-doped fiber ring laser with cascaded fiber Bragg gratings

We have experimentally shown wavelength mode switching in a dual-wavelength Erbium-doped single cavity fiber laser where the initial two wavelengths of 1 nm spacing are determined by the cascaded reflection type short-period fiber Bragg gratings having two different centre wavelengths of 1550.5 and 1551.5 nm. The lasing mode depends on the polarization in the ring cavity to migrate from one wavelength to another or operates in both modes in a polarization beam splitter output. To effectively control the polarization in the ring cavity, the polarization controllers were positioned before and after the polarization beam splitter. This method of wavelength switching provides a simple way of mode tuning in dual-wavelength fiber lasers.     

基于飞秒激光直写光纤光栅的掺镱光纤激光器

利用飞秒激光微加工技术,可以在光纤纤芯内直写出布拉格光栅,它与传统的光纤光栅制作方法相比,具有耗时短、无需光敏光纤、周期可任意设定、光栅稳定性高等优点。采用800 nm钛宝石飞秒激光器,在Hi1060光纤内写入一支8 mm长的布拉格光栅,光纤光栅的周期为2.9 μm,这是中心波长为1 042 nm的八阶光纤布拉格光栅。将所得光栅与一段有源的双包层光纤熔接,作为激光输出镜,利用975 nm的LD光纤模块作为泵浦源,采用端泵浦技术构成双包层光纤激光器。双包层光纤采用Nufern公司镱(Yb3+)离子掺杂双包层光纤,光纤长度3 m。所得激光器的输出功率为71.1 W,中心波长1 042 nm,带宽约为0.8 nm。     

基于飞秒激光直写光纤光栅的掺镱光纤激光器

 利用飞秒激光微加工技术,可以在光纤纤芯内直写出布拉格光栅,它与传统的光纤光栅制作方法相比,具有耗时短、无需光敏光纤、周期可任意设定、光栅稳定性高等优点。采用800 nm钛宝石飞秒激光器,在Hi1060光纤内写入一支8 mm长的布拉格光栅,光纤光栅的周期为2.9 μm,这是中心波长为1 042 nm的八阶光纤布拉格光栅。将所得光栅与一段有源的双包层光纤熔接,作为激光输出镜,利用975 nm的LD光纤模块作为泵浦源,采用端泵浦技术构成双包层光纤激光器。双包层光纤采用Nufern公司镱(Yb³⁺)离子掺杂双包层光纤,光纤长度3 m。所得激光器的输出功率为71.1 W,中心波长1 042 nm,带宽约为0.8 nm。     

Side-pumped fiber laser

A neodymium-doped side-pumped double-clad fiber laser operating at 1.06 µm is described. We report here, what is, to our knowledge, the first exclusively repetitive side-pumping scheme with two monomode laser diodes. Side-pumping has been realized by prism-fiber couplers. A pump-light-loss analysis at the pump positions has been performed. An output power of 13.5 mW is obtained with both diode lasers. The highest slope efficiency of 66% with respect to absorbed pump power at 809 nm is achieved when pumping with only one diode.     

Microjoule supercontinuum generation by stretched megawatt femtosecond laser pulses in a large-mode-area photonic-crystal fiber

Microjoule supercontinuum generation is demonstrated using a large-mode-area photonic-crystal fiber (PCF) pumped by an amplified stretched-pulse output of a mode-locked Cr:forsterite laser. A PCF with a mode area of 380 μm² is employed to transform 300-fs Cr:forsterite laser pulses with a peak-power of a few megawatts into a supercontinuum radiation with a spectrum spanning from 700 to 1800 nm and a total energy of 1.15 μJ.     

Transmission system over 3000 km with dispersion compensated by chirped fiber Bragg gratings

The limitation of the system with dispersion compensation by chirped fiber Bragg gratings is investigated in this paper. The transmission distance of the system based on chirped fiber Bragg gratings surpasses 3000 km. The bit error rate (BER) of the system is below 10⁻⁹ for as long as 2000 km. The BER is about 10⁻⁷ at 3000 km and, when forward error correction (FEC) is added, zero BER can be achieved. It is the longest transmission system with dispersion compensation by chirped fiber Bragg gratings.     

Effect of friction in ferrules on compression tuning characteristics of fiber Bragg gratings

The effect of friction in ferrules on compression tuning characteristics of fiber Bragg gratings (FBG) was observed and analyzed in this paper. It was demonstrated that the micro-bending of the fiber in the ferrule would cause friction between fiber and inner wall of the ferrule, and the friction would make a non-uniform strain in the FBG and degradations of its reflection spectrum. To avoid the effect, some measures have been applied including reducing the ferrule diameter to fit the fiber, and filling some lubrication in the ferrule, and so on. Near 10 nm tuning range can be obtained with good spectral performance.     

Monolithic fluoride-fiber laser at 1480 nm using fiber Bragg gratings

We report what we believe is the first monolithic fluoride-fiber laser making use of fiber Bragg gratings written directly in the doped fluoride-fiber core. The Tm(3+):ZBLAN fiber laser is upconversion pumped at 1070 nm and emits at 1480 nm. Using two different all-fiber cavities, we observed a threshold as low as 75 mW and a conversion efficiency of up to 40% with respect to launched pump power.