Multilayer dielectric mirrors generated chirp in femtosecond dye-ringlasers

Dietel, W.; Döpel, E.; Hehl, K.; Rudolph, W.; Schmidt, E.

doi:10.1016/0030-4018(84)90343-2

Cited by 40 publications

(9 citation statements)

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“…Recently Silvestri et al 3 evaluated the dispersion of mirrors by using a calculation of wavelength-dependent phase shifts due to dielectric multilayer mirrors for use in CPM lasers. Shortly after that, Dietel et al 6 confirmed experimentally that the dispersion that is due to the mirrors is equivalent to that from the inserted prism glass with negative cavity dispersion. In this Letter we experimentally clarify the sign and the optimum amount of mirror dispersion for the compensation of chirp from the dispersion and self-phase modulation proper to the CPM laser.…”

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confidence: 96%

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Femtosecond-pulse laser chirp compensated by cavity-mirror dispersion

Yamashita¹,

Ishikawa

Torizuka³

et al. 1986

Opt. Lett.

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The duration of pulses generated from a simple colliding-pulse mode-locked cw dye laser is measured as a function of cavity-mirror dispersion. The optimum amount of mirror dispersion of q(c) =_ + 1.8 X 10-28 sec 2 and a suitable mirror coating for upchirp compensation are identified. The adjustment of mirror dispersion only, without additional dispersive elements, generates continuous trains of pulses as short as 50 fsec.Since the development of continuous trains of pulses shorter than 100 fsec from a colliding-pulse modelocked cw (CPM) dye laser,' many efforts to generate shorter pulses directly from the laser have been carried out. 2 Those studies have shown that for the generation of shorter pulses, the most important thing is to compensate for the chirp arising from dispersion 0(X) and the phase modulation 0(t), which are due to intracavity optical elements. There are several sources of dispersion and phase modulation in the CPM laser.34 Sources of dispersion include the following: (1) the dispersion that is due to multilayer dielectric mirrors, which can have positive or negative dispersion, (2) the positive group-velocity dispersion arising from the unsaturated gain of an amplifier (Rhodamine 6G; R6G) and from the use of ethylene glycol (EG) solvents and air and prism glasses, (3) the negative group-velocity dispersion arising from the unsaturated loss in an absorber [diethyloxadicarbocyanine iodide (DODCI) and its photoisomer], and (4) the negative group-velocity dispersion that necessarily accompanies the angular dispersion introduced by the prisms. Sources of phase modulation include the positive self-phase modulation arising from the transient saturation of the gain of the amplifier and from the positive nonlinear refractive indices of EG, R6G, and DODCI as well as the negative self-phase modulation arising from the transient saturation of the DODCI absorption. Dietel et al. 4 produced pulses shorter than 60 fsec by the adjustment of the optical path of a positive-dispersion prism glass in the cavity for compensation of chirp from negative self-phase modulation. Valdmanis et al. 7 recently produced pulses as short as 27 fsec by adjusting the distance between prisms, resulting in negative cavity dispersion, and compensating for chirp from positive self-phase modulation. Consequently, Dietel's 4 conclusion that downchirp is dominant in the CPM laser is contrary to Valdmanis's conclusion 7 that upchirp is dominant. In addition, the cavity configurations for those experiments complicated the optical alignment of many elements and made it difficult to determine the inherent dispersion of the CPM laser' because of the additional insertion of one or four prisms, which led to negative cavity dispersion.It is known that the pulse duration of the CPM laser depends critically on the selection of the cavity mirrors, even if they have similar high quality and high reflectivity. 8 However, the criteria for the best mirror coating for the generation of the short pulses have not been studied experimentally. Recently S...

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“…The transmission is about 1% near the lasing wavelength. Intracavity dispersion was changed over a wide range from positive to negative values by using various flat mirrors for M, and M 6 . The values of 0(w) and R(co) as a function of the wavelength for 10 mirrors of different coatings were calculated.…”

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confidence: 99%

Femtosecond-pulse laser chirp compensated by cavity-mirror dispersion

Yamashita¹,

Ishikawa

Torizuka³

et al. 1986

Opt. Lett.

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“…However, a previous study of chirped multilayer coatings with layer thicknesses following monotonic variations revealed that the GDD is strongly perturbed by some Fabry-Perotlike resonances in these simple structures.' 7 Our studies have indicated that the undesirable resonant features can be almost completely eliminated by slight adjustment of the layer thicknesses. This finding has been a most important step toward the practical realization of dispersive mirrors having a group delay that is a linear function of optical frequency.…”

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confidence: 81%

“…7 -' 3 Whereas standard quarter-wave dielectric mirrors were shown to introduce negligible dispersion at the center of their reflectivity bands, 7 ' 8 various specific high-reflectivity coatings (Gires-Tournois interferometers, double-stack mirrors, etc.) with adjustable GDD (through angle tuning) were devised and used for the precise control of intracavity dispersion in femtosecond dye lasers.'…”

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confidence: 99%

Chirped multilayer coatings for broadband dispersion control in femtosecond lasers

et al. 1994

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Optical thin-film structures exhibiting high reflectivity and a nearly constant negative group-delay dispersion over frequency ranges as broad as 80 THz are presented. This attractive combination makes these coatings well suited for intracavity dispersion control in broadband femtosecond solid-state lasers. We address design issues and the principle of operation of these novel devices.The relevance of intracavity dispersion control in passively mode-locked ultrashort-pulse laser was recognized soon after the appearance of the first systems operating in the femtosecond domain.' Negative dispersion that is due to wavelengthdependent refraction in a pair of Brewster-angled prisms combined with positive material dispersion proved to be an efficient and convenient means of controlling the net group-delay dispersion (GDD) inside the laser cavity. 2 In solid-state lasers femtosecond pulse generation invariably relies on a net negative intracavity GDD because of an ultrafast self-phase modulation caused by the optical Kerr effect in the laser medium. Hence prism pairs have become standard components in these systems. The interplay between negative GDD and Kerr-induced self-phase modulation, often referred to as solitonlike shaping, appears to be the dominant pulse-forming mechanism that determines the steady-state pulse duration in femtosecond solidstate lasers. 3 In practical prism-pair-controlled broadband laser systems a major limitation to ultrashort pulse generation originates from the variation of the intracavity GDD with wavelength. The principal source of this high-order dispersion was found to be the prism pair. 3 ' 4 In this Letter we report the novel development of chirped multilayer mirror coatings that can exhibit essentially constant negative GDD over a frequency range as broad as 80 THz. Careful design permits higher-order contributions to the mirror phase dispersion to be kept at low values or to be chosen such that high-order phase errors introduced by other cavity components (e.g., the gain medium) are canceled. Replacing the prism pair with these novel devices offers the potential of generating pulses that are shorter than previously achievable directly from the laser. In addition, this simplifies the cavity design and may permit the construction of more compact and reliable femtosecond sources.The first thorough investigations of the frequencydependent phase retardation (phase dispersion) of multilayer dielectric coatings date back to the early 1960's.5, The emergence of femtosecond lasers in the 1980's has led to a revival of interest in this field. 7 -' 3 Whereas standard quarter-wave dielectric mirrors were shown to introduce negligible dispersion at the center of their reflectivity bands, 7 ' 8 various specific high-reflectivity coatings (Gires-Tournois interferometers, double-stack mirrors, etc.) with adjustable GDD (through angle tuning) were devised and used for the precise control of intracavity dispersion in femtosecond dye lasers.' 4 " 5 However, the GDD introduced by these mirr6r coatings ...

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“…In recent decades, for example, the development of IR/visible/UV sources with pulse lengths extending down to the few-femtosecond range have stimulated the systematic re-investigation of the performance the performance of many types of optical elements and instruments, including mirrors, multilayers, diffraction gratings, refractive lenses, monochromators, and interferometers [2][3][4][5][6][7][8][9][10]. More recently, the advent of high power laser techniques for generating ultra-short X-ray pulses from plasmas [11], along with the continuing study and design development of a novel source of even shorter ultra-intense X-ray pulses, the X-Ray Free Electron Laser (XRFEL) [12], have stimulated a number of exploratory short-pulse investigations extending into the X-ray range [13,14,15].…”

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confidence: 99%

Short-pulse limits in optical instrumentation design for the SLAC Linac Coherent Light Source (LCLS)

Tatchyn¹

2000

AIP Conference Proceedings

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Abstract. The source properties of linac-driven X-Ray Free-Electron Lasers (XRFELs) operating in the Self-Amplified Spontaneous Emission (SASE) regime differ markedly from those of ordinary insertion devices on synchrotron storage rings. In the case of the 1.5 Å SLAC Linac Coherent Light Source (LCLS), the longitudinal output profile typically consists of a randomly-distributed train of fully-transversely-coherent micropulses of randomly varying intensity and an average length (corresponding to the source coherence length) two to three orders of magnitude smaller than the transverse diameter of the beam. Total pulse lengths are typically of the same order of size as the beam diameter. Both of these properties can be shown to significantly impact the performance of otherwise conventional synchrotron radiation optics; viz., mirrors, lenses, zone plates, crystals, multilayers, etc. In this paper we outline an analysis of short-pulse effects on selected optical components for the SLAC LCLS and discuss the implications for critical applications such as microfocusing and monochromatization.

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Multilayer dielectric mirrors generated chirp in femtosecond dye-ringlasers

Cited by 40 publications

References 9 publications

Femtosecond-pulse laser chirp compensated by cavity-mirror dispersion

Femtosecond-pulse laser chirp compensated by cavity-mirror dispersion

Chirped multilayer coatings for broadband dispersion control in femtosecond lasers

Short-pulse limits in optical instrumentation design for the SLAC Linac Coherent Light Source (LCLS)

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