5. Conclusions

Transient fiber Bragg gratings has a great potential for all-optical, all-fiber, fast optical switching. Many challenges have yet remained to be investigated in this field, mostly improving the efficiency of the grating for practical applications, methods to generate them, and life time of such devices.

Achieving Kerr gratings for ultrafast switching is challenging in silica fibers since the effect is much weaker than inscription of permanent gratings. However, it may be feasible in highly nonlinear fibers or waveguide materials. Semiconductor waveguides and materials are promising for both Kerr-based transient gratings and free-carrier-based gratings. Furthermore, it should be possible to implement with low-power, low-cost diodes rather than high-power femtosecond lasers—at the cost of slower rise time.

The immunization technique presented here can be used to implement transient thermal gratings in transparent materials and may serve as a diagnostic tool for dielectric materials with different compositions and doping. Furthermore, the diffusion of transient thermal gratings is highly dependent on the grating period; thus, many time scales and wavelengths are accessible by simply choosing a suitable mask and illuminating wavelength.

Several applications may rise from transient gratings in fibers and remain to be demonstrated: fiber laser Q-switching and modulation, generation of sub-ns pulses—a regime not accessible with Q-switching or mode-locking technique, diagnostic tools, and more.

## Acknowledgements

We would like to thank Dr. Yonatan Sivan from the Electro-Optics Unit in Ben-Gurion University of the Negev, for his contribution and help in understanding transient grating theory.

Author details

35

the Negev, Beer-Sheva, Israel

Femtosecond Transient Bragg Gratings DOI: http://dx.doi.org/10.5772/intechopen.84448

provided the original work is properly cited.

Avishay Shamir1,2\*, Aviran Halstuch1 and Amiel A. Ishaaya<sup>1</sup>

2 Israel Center of Advanced Photonics (sICAP), Yavne, Israel

\*Address all correspondence to: avishay.shamir@gmail.com

1 Department of Electrical and Computer Engineering, Ben-Gurion University of

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Femtosecond Transient Bragg Gratings DOI: http://dx.doi.org/10.5772/intechopen.84448

We also note here that thermal grating diffusion time is highly dependent on grating period. The diffusion time is opposite to the square of the grating period; thus, working with first-order grating can reduce the time scale by a factor of four. The applicability to transient thermal grating for higher pulse rate and life time of

Transient fiber Bragg gratings has a great potential for all-optical, all-fiber, fast optical switching. Many challenges have yet remained to be investigated in this field, mostly improving the efficiency of the grating for practical applications,

Achieving Kerr gratings for ultrafast switching is challenging in silica fibers since the effect is much weaker than inscription of permanent gratings. However, it may be feasible in highly nonlinear fibers or waveguide materials. Semiconductor waveguides and materials are promising for both Kerr-based transient gratings and free-carrier-based gratings. Furthermore, it should be possible to implement with low-power, low-cost diodes rather than high-power femtosecond lasers—at the cost

The immunization technique presented here can be used to implement transient

Several applications may rise from transient gratings in fibers and remain to be

We would like to thank Dr. Yonatan Sivan from the Electro-Optics Unit in Ben-Gurion University of the Negev, for his contribution and help in understanding

thermal gratings in transparent materials and may serve as a diagnostic tool for dielectric materials with different compositions and doping. Furthermore, the diffusion of transient thermal gratings is highly dependent on the grating period; thus, many time scales and wavelengths are accessible by simply choosing a suitable mask

demonstrated: fiber laser Q-switching and modulation, generation of sub-ns pulses—a regime not accessible with Q-switching or mode-locking technique,

such device is elaborated elsewhere [95].

methods to generate them, and life time of such devices.

Fiber Optic Sensing - Principle, Measurement and Applications

5. Conclusions

of slower rise time.

and illuminating wavelength.

diagnostic tools, and more.

Acknowledgements

transient grating theory.

34
