Broadband IR supercontinuum generation using single crystal sapphire fibers

Abstract

In this paper, an investigation on broadband IR supercontinuum generation in single crystal sapphire fibers is presented. It is experimentally demonstrated that broadband IR supercontinuum spectrum (up to 3.2microm) can be achieved by launching ultra-short femtosecond laser pulses into single crystal sapphire fiber with a dimension 115microm in diameter and 5cm in length, which covers both the near IR spectral region and the lower end of the mid-IR spectral range. Furthermore, the mechanism of supercontinuum generation in single crystal sapphire fibers is briefly addressed. When the fiber length is shorter than the dispersion length, the self-phase modulation dominates the broadening effect. In this case, the broad supercontinuum spectrum with a smooth profile can be obtained. However, when the fiber length is longer than the dispersion length, the soliton-related dynamics accompanied by the self-phase modulation dominates the broadening effect. There are discrete spikes in the spectrum (corresponding to different order solitons). The above assumption of supercontinuum generation mechanism is quantitatively modeled by the computer simulation program and verified by the experimental results. Thus, one can adjust the spectral profile by properly choosing the length of the sapphire fibers. The broad IR spectral nature of this supercontinuum source can be very useful in a variety of applications such as broadband LADAR, remote sensing, and multi-spectrum free space communications.

Mid-infrared supercontinuum generation using dispersion-engineered Ge_115As_24Se_645 chalcogenide channel waveguide

“…In recent years, several experimental and theoretical investigations on mid-infrared SC generation were reported in ChG planar waveguides [13][14][15], ChG fibers [16][17][18][19][20][21][22][23][24][25][26][27][28], single crystal sapphire fibers [29], silicon-on-insulator (SOI) wire waveguides [30], ZBLAN fiber [31], fluoride glass [32] and germano-silicate fibers [33]. Gai et al [13] reported SC generation from 2.9 µm to 4.2 µm in dispersion-engineered As 2 S 3 glass rib waveguide (6.6 cm long) pumped with 7.5 ps duration pulses at a wavelength of 3.26 µm with a pulse peak power of around 2 kW.…”

Thermal stability of microstructural and optical modifications induced in sapphire by ultrafast laser filamentation

“…23 Based on these refractive index changes induced in the surroundings of focal volume and by translation of the sample during irradiation, channel buried waveguides have been fabricated with a great relevance as potential integrated laser sources and high temperature optical sensors. [24][25][26] Nevertheless, and despite its interest from both fundamental and applied point of views, the time and thermal stability of the microstructural changes induced in the sapphire network ͑i.e., stability of the fabricated waveguides͒ after ultrafast laser inscription are still unexplored. This information is of relevance since it provides fundamental information about the physics beyond the ultrafast driven microstructural modifications and establishes the working limits of the fabricated photonic devices.…”

High efficiency IR supercontinuum generation and applications: a review

“…Thus, it is possible to generate high average power IR SC source (up to 3.1 micron) by employing single crystal sapphire fiber. In the last a couple of years, we have demonstrated supercontinuum generation in Sapphire fiber [4,[7][8][9][10], to be reviewed in detail in Section 2. To further extend the IR wavelength range, in the section 3 of this paper, we will present a new type of IR fiber, which not only has a broader spectral range (up to seven microns) but also has a high laser damaging threshold.…”