Design and Development of Compact High-Energy Femtosecond Oscillators

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

0456928 Fujimoto This proposal is for international cooperative research between investigators at the Massachusetts Institute of Technology and the Koc University in Istanbul, Turkey. This proposal is for travel expenses for investigators from Koc University in Turkey to visit M.I.T. in order to perform collaborative research. The proposal follows the format of the Scientific and Technical Research National Science Council of Turkey (TUBITAK). The proposal is also submitted to Tubitak in Turkey for support of research expenses of our collaborator in Turkey. High-energy femtosecond oscillators based on solid-state media, such as Ti3 :Al2O3 and Cr4+:forsterite have numerous applications in ultrafast phenomena and nonlinear optics, including such diverse applications as nonlinear frequency generation, pump probe measurement, micromachining and biomedical imaging. Recently it was proposed that the pulse energies of laser systems can be scaled up by using extended laser resonators. For a given average power, extending the laser cavity length lowers the pulse repetition rate and, therefore, increases the pulse energy; thus, generating high-energy pulses without the need for more complex and expensive methods such as cavity dumping or amplification. In a practical system, it is also important to maintain compactness as cavity length is increased. The subject of this proposal is femtosecond laser development. It involves the design and experimental investigation of laser oscillators that are compact and can produce high-energy pulses. The femtosecond lasers to be investigated are based on the tunable, solid-state Ti 3+ :Al2O3 and Cr 4+ :forsterite systems that operate in the near infrared range between 700 and 1400 nm. The broad gain bandwidths of these materials enables the generation of femtosecond pulses. Kerr-lens mode-locking (KLM) will be employed, along with intracavity dispersion compensation using double-chirped mirrors to achieve broad tunability or very short pulse, broadband operation. Multi-pass laser cavities (MPCs) will be designed which can dramatically reduce laser repetition rate and increase pulse energies while maintaining a compact laser design. The scope of the proposed project is the design, development, and application of compact, high- energy femtosecond lasers. The objectives include: 1) Design multi-pass cavity (MPC) lasers using Cr4+:forsterite for generation of femtosecond pulses in the 1.1 to 1.4 um range, 2) Experimentally investigate the femtosecond MPC lasers using Cr4+:forsterite in the 1.1 -1.4 um range, and Ti3+:Al2O3 in the 700 -1000 nm range, 3) Explore the fundamental limits of pulse energy that can be generated with MPC laser designs, 4) Perform second-harmonic generation studies with the MPC Cr4+:forsterite laser to obtain high pulse energies at visible wavelengths, and 5) Demonstrate selected applications of the MPC Cr4+:forsterite and Ti3+:Al2O3 lasers for biomedical imaging and ultrafast pump-probe studies. If successful, this research will enable the development of a new class of femtosecond lasers that achieve pulse energies significantly higher than what is currently possible with current femtosecond laser oscillators. This will enable a wide range of new applications without the need for femtosecond laser amplifiers. Broader Impacts: This program is an international collaboration. It will develop new laser technology in both laboratories in the U.S. and in Turkey that can be used for future applications, such as biomedical imaging, pump-probe measurements, and micromachining. It will train graduate students at the master's and doctoral levels who will be specialized in lasers and ultrafast phenomena. Both countries will gain expertise in fundamental and applied research in the field of ultrafast lasers and measurement. These fields are important to future advances in areas including high-speed photonics and communications, semiconductor physics, biology, and photochemistry. The development of new technologies in optics and photonics can enhance high-technology and industrial development, leading to economic growth.