With the development of high power fiber oscillators, it is urgent to fabricate fiber Bragg gratings (FBGs) on large core fibers. Here, a pair of FBGs in fibers with core diameter of 30 μm are fabricated based on femtosecond laser phase mask scanning method. The reflectivity of high-reflectivity FBG (HR-FBG) is more than 99% with the central wavelength of 1080 nm and the 3dB bandwidth of 3.6 nm. The reflectivity of output coupler FBG (OC-FBG) is about 10% with the central wavelength of 1079.8 nm and the 3dB bandwidth of 2 nm. Furthermore, an all-fiber oscillator is built based on the fs-written FBGs, and the maximum output power of 6.4 kW is realized with the optical-optical conversion efficiency of 74%. The temperatures of HR-FBG and LR-FBG are 90 and 49℃, respectively. This work demonstrates that the large core diameter FBG written by femtosecond laser has excellent performance, which is of great significance for the development of high power fiber oscillators.
Fiber tapering technology has been used to realize low-loss coupling from solid-core fibers to antiresonant hollow-core fibers (AR-HCFs) at low-power level, by inserting the tapered solid-core fibers into the hollow-core of AR-HCFs. Here, we have demonstrated the high-power coupling capacity of this way. For ice-cream type AR-HCF, a transmission efficiency of ~47% is achieved with injected 1080 nm laser power of ~90 W in a ~2 m HCF; for nodeless type AR-HCF, a transmission efficiency of ~40% is achieved with injected 1550 nm laser power of ~32 W in a ~2 m HCF. The output mode field with good beam quality shows the mode filtering characteristics of AR-HCFs.
Hollow-core fibers (HCFs) provide an ideal environment for the interaction of light and gases, which gives birth to a novel kind of lasers, namely fiber gas lasers (FGLs). Although there is a rapid development of FGLs in the past years, highly efficient and stable coupling of the pump light is still a key limit for their applications in the future. Here, we propose and fabricate the HCF end-cap for the first time. The measured results show that the HCF end-cap can bear several hundreds of watt laser power, and the coupling efficiency is around 70%. This work opens new opportunity for the development of high-power FGLs.
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.