Pulse Asymmetry in the Colliding-pulse Mode-locked Dye Laser

1992

Optics Communications

Frequency tunable femtosecond light pulses are generated in a cw pumped linear group velocity dispersion balanced passive mode-locked rhodamine 6G dye laser by birefringent filter tuning. The saturable absorbers DODCI (duration A/j < 100 fs in frequency region between 607 nm and 620 nm), DQOCI (A/ L < 100 fs between 585 nm and 615 nm). and TCVEBI (A/, < 100 fs between 585 nm and 615 nm) in ethylene glycol were applied.

Section: Saturable Absorber Dodcimentioning

confidence: 99%

Section: Saturable Absorber Tcvebimentioning

confidence: 99%

Generation of frequency tunable femtosecond pulses in a cw pumped linear dispersion-balanced passive mode-locked rhodamine 6G dye laser

Wittmann

Penzkofer

1992

Optics Communications

“…It is applied in the wavelength region between 574 nm [9] and 645 nm [4]. Especially in a prism balanced colliding-pulse mode-locked rhodamine 6G ring dye laser pulse durations down to 20 fs have been generated around 620 nm using DODCI as the mode-locking dye [10,11].…”

Section: Introductionmentioning

confidence: 99%

“…For DODCI in ethylene glycol the absorption peak of the N-isomer is at 585 nm and that of the P-isomer is at 620 nm [12]. In some papers [3,11,15,16] the bleaching of the ground-state P-isomer absorption is thought to be responsible for the picosecond and femtosecond pulse generation in passively mode-locked rhodamine 6G dye lasers in the wavelength region above 600 nm.…”

Section: Introductionmentioning

confidence: 99%

Saturable absorption dynamics of DODCI

Penzkofer

1991

Opt Quant Electron

The saturable absorption dynamics of DODCI in a femtosecond dye laser is studied theoretically. The N-isomer and P-isomer photoisomerization dynamics is included. The wavelength region between 570 nm and 650 nm is considered where the N-isomer and P-isomer absorption dynamics changes from short-wavelength to longwavelength So-Si excitation. The slow saturable absorber DODCI shortens a circulating pulse in a laser oscillator down to femtosecond duration if the gain medium compensates the absorber losses. Fast local relaxation in the S 1 -state in the case of short-wavelength excitation and fast level refilling in the S^state in the case of longwavelength excitation facilitate the pulse shortening and the background signal suppression. In some papers [3, 11, 15, 16] the bleaching of the ground-state P-isomer absorption is thought to be responsible for the picosecond and femtosecond pulse generation in passively mode-locked rhodamine 6G dye lasers in the wavelength region above 600 nm. IntroductionIn this paper a detailed numerical analysis of the saturable absorption dynamics of DODCI in the wavelength region between 570 nm and 650 nm is given. The single transit of a pulse through the absorber and the repetitive passage of a pulse circulating in an oscillator are studied. The N-isomer-P-isomer photoisomerization dynamics is included [13,14]. In the long-wavelength absorption region the bleaching dynamics of the fraction of molecules interacting with the laser light is considered [17,18]. It is found that the slow saturable absorber is able to shorten nanosecond Gaussian pulses down to femtosecond pulses in multiple passages if the gain medium compensates the absorber losses. The fast relaxation of the excited Franck-Condon level in the S,-state in the case of short-wavelength excitation, and the fast spectral cross-relaxation in the S 0 -ground state in the case of

“…Typical average output powers were 10 mW. Figure 1 shows the autocorrelation trace (recording time is 10 ^s) and the spectrum (recording time is 100 ms) of pulses which have been recorded using a DQTCI concentration of 2.6xl0~4 mol/litre («9% small signal loss due to saturable absorber) and a pump power of 5 W. The pulse duration is At=50 fs (fwhm) assuming a sech 2 -intensity pulse shape (AT/A/= 1.543 [3,20], where AT is the full halfwidth of the autocorrelation trace). The temporal-spectral bandwidth product is APA{«0.25 (theoretical value for a sedr-pulse is AJ>A/=0.315 [3,20]).…”

mentioning

confidence: 99%

Femtosecond pulse generation around 650 nm in a passive mode-locked Kiton Red dye laser

Petrov

Wittmann

et al. 1993

Optics Communications

Sub 100 fs light pulses have been generated in the spectral region between 640 and 660 nm (the shortest duration being 50 fs at 653 nm) by passive mode-locking of a Kiton Red dye laser with the saturable absorber DQTCI.Nearly the whole visible and near infrared range (with some gaps) has been covered by various amplifying dye-saturable absorber combinations yielding femtosecond light pulses in cw passive or hybrid mode locked lasers [1][2][3][4]. Pulse durations below 150 fs were obtained in some of these combinations by group velocity dispersion balanced laser operation [5].In the spectral region around 650 nm sub 100 fs pulse generation has not been reported so far. The longest wavelength achieved by passive mode-locking of a Rhodamine 6G laser was 640 nm [ 6 ]. In this laser 50 fs pulses at 640 nm have been generated by the saturable absorber TCETI. Energy transfer passive mode-locking with an argon ion pump laser has been applied to cover the 652-694 nm region with Rhodamine 6G+Sulforhodamine 101 mixtures as gain medium and DQTCI or DCCI as saturable absorbers [ 7,8 ]. The shortest pulse durations obtained were 58 fs at 685 nm [8] and 120 fs at 666 nm [7]. Applying hybridly mode-locked systems pumped by the second harmonic of Nd:YAG lasers [9,10], pulses of 65 fs duration at 640 nm [9] have been obtained in a Rhodamine 6G/DODCI laser, and pulses of 60 fs duration at 675 nm were generated using Rhodamine 101 or Sulforhodamine 101 as gain media and DQTCI as absorber medium [10]. Subpicosecond Rhodamine B lasers have been operated 1 On leave from the Faculty of Physics, Sofia University, BG-1126 Sofia, Bulgaria.around 650 nm [10][11][12]. Cw passive mode-locking with DQTCI was achieved in the wavelength region of 616-658 nm [11]. However, the shortest duration was 220 fs at 635 nm [11]. Hybrid mode-locking of Rhodamin B lasers resulted in pulses of duration down to 320 fs in the spectral region between 604 and 632 nm when DQTCI or DDBCI were used as saturable absorbers [10,12]. Using Oxazine 720 as saturable absorber pulse durations down to 187 fs were obtained around 649 nm [10].Here we report on passive mode-locking of a Kiton Red laser with the saturable absorber DQTCI [13] producing sub 100 fs pulses in the wavelength region of 640-660 nm. The dyes Kiton Red 620 (Sulforhodamine B, free of sodium) [13,14] and DQTCI (1,3' -diethyl-4,2' -quinolythiacarbocyanine iodide) [13,15] were purchased from Lambda Physik. The fluorescence quantum yield of Kiton Red 620 in ethylene glycol was determined to be