Gregg Sucha

Ultrafast lasers : technology and applications

LASER SYSTEMSUltrafast Solid-State Lasers, R. Paschotta and U. KellerUltrafast Solid-State Amplifiers, F. SalinUltrafast Fiber Oscillators, M.E. FermannUltrashort-Pulse Fiber Amplifers, A. GalvanauskasUltrafast Single- and Multiwavelength Modelocked Semiconductor Lasers: Physics and Applications, P.J. DelfyettAPPLICATIONSOverview of Industrial and Medical Applications of Ultrafast Lasers, G. SuchaMicromachining, S. NolteStructural Changes Induced in Transparent Materials with Ultrashort Laser Pulses, C.B. Schaffer, A.O. Jamison, J.F. Garcia, and E. MazurRapid Scanning Time Delays for Ultrafast Measurement Systems, G. SuchaElectro-Optic Sampling and Field Mapping, J.F. Whitaker and K. YangTerahertz Wave Imaging and Its Applications, Q. Chen and X.-C. ZhangPhase-Controlled Few-Cycle Light, G. Tempea, R. Holzwarth, A. Apolonski, T. W. H?nsch, and F. KrauszUltrahigh Bit Rate Communication Systems, M. NakazawaNonlinear Microscopy with Ultrashort Pulse Lasers, M. Mnller and J. SquierOptical Coherence Tomography, J.G. Fujimoto, M. Brezinski, W. Drexler, I. Hartl, F. K?rtner, X. Li, and U. MorgnerUltrafast Lasers in Ophthalmology, R.M. Kurtz, M.A. Sarayba, and T. JuhaszIndex

Portable terahertz system and its applications

Industrial applications of THz techniques require compact and reliable systems. We have designed and constructed two portable THz systems integrated with femtosecond, erbium- doped fiber lasers. Terahertz emitters based on photoelectron-transport and optically-rectification were tested in the system. With the use of a 10-mW laser pump beam, the signal-to-noise ratio of the system is greater than 5,000. We studied THz beam generation and detection with two different laser wavelengths. Under the consideration of group velocity matching, the frequency response of the THz system is calibrated. Our portable systems have been applied for the coherent measurement of the refractive index and dielectric constant of polymer thin films, which will play an important role in the ongoing quest for higher speeds in integrated circuits. The measurement is based on a comparison of THz phases with and without the film. The refractive index of thin film can be derived according to the phase difference. The system has sufficient sensitivity to perform these measurements on films as thin as 10 microns. We have also used one of these systems for THz measurements of molecular rotation spectra in air/vapor mixtures.

Fiber lasers in ultrafast optics

The current status of ultrafast fiber lasers is discussed. Recent advances in optical fiber designs as well as improved saturable absorbers have greatly improved the performance and the reliability of ultrafast fiber oscillators. Equally significant have been improvements in ultrafast fiber amplifier designs and compact chirped pulse amplification systems in conjunction with chirped periodically-poled LiNbO3, which now allow the manufacture of compact ultrafast fiber laser systems that can exceed the performance of conventional ultrafast lasers based on bulk optics. The unique size advantage of fiber lasers opens up the field of ultrafast optics to novel OEM-type applications. For example ultrafast fiber lasers have been successfully employed as subsystems in all-optical time delay scanning, for two-photon microscopy as well as for THz pulse generation.

Novel ultrashort-pulse fiber lasers and their applications

The development of ultrashort pulse laser technology will have a strong impact on the advancement of laser machining. Ultrashort laser pulses can reduce the heat-affected zone and the shock-affected zone, resulting in much cleaner cuts, and therefore higher precision. Also, ultrashort laser pulses have shown remarkable opportunity for processing transparent materials such as glass, fused silica, and sapphire. However, acceptance of ultrafast technology is hindered by the size, cost, and complexity of ultrafast lasers. In this paper, we describe recent progress in fiber- based ultrafast laser technology which promises to be sufficiently compact, rugged, and potentially low-cost.

CW passive mode-locking evolved from Q-switched mode-locking in erbium doped fiber lasers

Summary form only given. We report a new mode-locking mechanism, where the use of a two-photon absorber in addition to a saturable absorber allows for CW mode-locking to reliably evolve from Q-switched mode locking. An optimal design of the two-photon absorber limits the peak power of the Q-switched pulses via optical limiting and thus aids in preventing damage to the saturable absorber. Moreover, the threshold for optical limiting is chosen to set an optimum stability point for CW mode-locked operation.

Highly efficient, low-noise Yb femtosecond fiber source

Summary form only given. With the recent availability of Raman-shifted, widely tunable Er fiber laser pulse sources, the direct injection of Yb fiber amplifiers with femtosecond pulses from a frequency-converted Er-fiber laser has become possible. The exploitation of the unique efficiency and large bandwidth of Yb fiber amplifiers thus allows the construction of highly compact ultrafast laser sources operating at W-level average powers. However, in most applications very low noise levels from such systems are needed, which may seem challenging due to the nonlinear processes involved from transferring the output of an Er fiber laser at 1.56 /spl mu/m to the 1 /spl mu/m region. We demonstrate for the first lime to our knowledge that a femtosecond Yb fiber source can be operated in an extremely low noise regime. Injected with a Raman-shifted and frequency doubled Er femtosecond fiber laser low noise performance is achieved by exploiting self-limiting nonlinear frequency conversion in both the Raman shifting stage as well as the frequency doubling stage. Reliable operation of the Yb-amplifier is obtained by employing side-pumping and polarization maintaining (PM) fibers.

Time-Domain Jitter Measurement of Modelocked Fiber Lasers

The timing jitter of modelocked Er:doped fiber lasers is measured using a new time-domain method involving cross-correlation. The measured jitter is compared with the quantum-limited timing jitter predicted by the theory of Haus & Mecozzi.

Rapid temporal scanning of ultrafast lasers

As ultrafast lasers find their way into new application areas, there remain some technological barriers to utilizing their full potential.