Tunable Optical Gain from Soluble Thiophene-Based Oligomers

2001 ◽  
Vol 665 ◽  
Author(s):  
M. Anni ◽  
G. Gigli ◽  
M. Zavelani-Rossi ◽  
C. Gadermaier ◽  
G. Lanzani ◽  
...  
Keyword(s):  
Cross Section ◽  
Optical Gain ◽  
Visible Range ◽  
High Solubility ◽  
Relaxation Dynamic ◽  
Time Resolved ◽  
Pump And Probe ◽  
Gain Cross Section ◽  
Probe Measurements ◽  
Photoluminescence Efficiency

ABSTRACTTunable optical gain is demonstrated, through pump and probe measurements, in spin coated neat films of soluble S,S-dioxide oligothiophenes with different functionalization pattern. The molecular functionalization with alkyl and aryl groups allows us to obtain photoluminescence efficiency up to 70%, good chemical stability, high solubility and tunable gain along the visible range from 470 nm to 660 nm. The gain cross section is up to 9*10-18 cm2. The gain relaxation dynamic is studied through time resolved pump and probe measurements. A comparison with some of the best organic materials for laser application is presented. From these results we conclude that thienyl-S,S-dioxide oligothiophenes are interesting materials for applications to organic lasers and amplifiers.

Pump-Probe Measurements Using Silicon Nanocrystal Waveguides

2003 ◽  
Vol 770 ◽  
Author(s):  
Nathanael Smith ◽  
Max J. Lederer ◽  
Marek Samoc ◽  
Barry Luther-Davies ◽  
Robert G. Elliman
Keyword(s):  
Probe Beam ◽  
Time Resolution ◽  
Pump Beam ◽  
Silicon Nanocrystals ◽  
Continuous Wave ◽  
Optical Gain ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Probe Measurements

AbstractOptical pump-probe measurements were performed on planar slab waveguides containing silicon nanocrystals in an attempt to measure optical gain from photo-excited silicon nanocrystals. Two experiments were performed, one with a continuous-wave probe beam and a pulsed pump beam, giving a time resolution of approximately 25 ns, and the other with a pulsed pump and probe beam, giving a time resolution of approximately 10 ps. In both cases the intensity of the probe beam was found to be attenuated by the pump beam, with the attenuation increasing monotonically with increasing pump power. Time-resolved measurements using the first experimental arrangement showed that the probe signal recovered its initial intensity on a time scale of 45-70 μs, a value comparable to the exciton lifetime in Si nanocrystals. These data are shown to be consistent with an induced absorption process such as confined carrier absorption. No evidence for optical gain was observed.

scholarly journals Deep Blue Light Amplification from a Novel Triphenylamine Functionalized Fluorene Thin Film

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 79 ◽  
Author(s):  
Tersilla Virgili ◽  
Marco Anni ◽  
Maria Luisa De Giorgi ◽  
Rocio Borrego Varillas ◽  
Benedetta M. Squeo ◽  
...  
Keyword(s):  
Cross Section ◽  
High Performance ◽  
Optical Gain ◽  
High Gain ◽  
Optically Pumped ◽  
Deep Blue ◽  
Light Amplification ◽  
Gain Cross Section ◽  
Low Threshold ◽  
Narrow Emission

The development of high performance optically pumped organic lasers operating in the deep blue still remains a big challenge. In this paper, we have investigated the photophysics and the optical gain characteristics of a novel fluorene oligomer functionalized by four triphenylamine (TPA) groups. By ultrafast spectroscopy we found a large gain spectral region from 420 to 500 nm with a maximum gain cross-section of 1.5 × 10−16 cm2 which makes this molecule a good candidate for photonic applications. Amplified Spontaneous Emission measurements (ASE) under 150 fs and 3 ns pump pulses have revealed a narrow emission at 450 nm with a threshold of 5.5 μJcm−2 and 21 μJcm−2 respectively. Our results evidence that this new fluorene molecule is an interesting material for photonic applications, indeed the inclusion of TPA as a lateral substituent leads to a high gain and consequently to a low threshold blue organic ASE.

Time-resolved curling-probe measurements of electron density in high frequency pulsed DC discharges

2015 ◽  
Vol 55 (1) ◽  
pp. 016101 ◽  
Author(s):  
Anil Pandey ◽  
Wataru Sakakibara ◽  
Hiroyuki Matsuoka ◽  
Keiji Nakamura ◽  
Hideo Sugai
Keyword(s):  
Electron Density ◽  
High Frequency ◽  
Time Resolved ◽  
Pulsed Dc ◽  
Probe Measurements

Optical absorption and emission spectral studies of phthalocyanine molecules in DMF

2001 ◽  
Vol 05 (05) ◽  
pp. 456-459 ◽  
Author(s):  
G. A. KUMAR ◽  
J. THOMAS ◽  
N. V. UNNIKRISHNAN ◽  
V. P. N. NAMPOORI ◽  
C. P. G. VALLABHAN
Keyword(s):  
Optical Absorption ◽  
Cross Section ◽  
Emission Cross Section ◽  
Optical Gain ◽  
Spectral Studies ◽  
Dimethyl Formamide ◽  
Free Base ◽  
Dipole Strength ◽  
Spectral Parameters ◽  
Absorption And Emission

Optical absorption and emission spectral studies of various phthalocyanine ( Pc ) molecules in dimethyl formamide (DMF) solvent are reported in this paper. Measurements have been done for free base, Eu , Fe , Mn , Sm , Cu , Zn , Nd and La Pc - s . The principal optical transitions viz B and Q are identified and some of the important spectral parameters such as molar extinction coefficient (ε), absorption cross section (σa), dipole strength (q) and oscillator strength (f) are evaluated for the prominent Q-band. The measured radiative parameters viz emission cross section (σe), fluorescence bandwidth (Δλ) and optical gain (G) show wide variation among different systems. The results obtained are compared with other solid matrices such as glass and polymer.

scholarly journals Fourier transform measurement of NO2 absorption cross-section in the visible range at room temperature

1996 ◽  
Vol 25 (3) ◽  
pp. 289-305 ◽  
Author(s):  
A. C. Vandaele ◽  
C. Hermans ◽  
P. C. Simon ◽  
M. Van Roozendael ◽  
J. M. Guilmot ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Cross Section ◽  
Absorption Cross Section ◽  
Room Temperature ◽  
Visible Range ◽  
Absorption Cross

Time-Resolved Small Angle X-Ray Scattering and Dynamic Light Scattering Studies of Sol-Gel Transition in Gelatin

1988 ◽  
Vol 143 ◽  
Author(s):  
Dan Q. Wu ◽  
Benjamin Chu
Keyword(s):  
Light Scattering ◽  
Cross Section ◽  
Sol Gel ◽  
Slow Mode ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Saxs Intensity ◽  
Sol Gel Transition ◽  
Gel Transition

AbstractStructural and dynamical properties of an aqueous gelatin solution (5 wt%, 0.1M NaCi, pH=7) in a sol-gel transition were studied by time-resolved small angle x-ray scattering (SAXS) and dynamic light scattering (DLS) after quenching the gelatin sol at ∼45”C to 11°C. SAXS intensity measurements suggested the presence of gel fibrils which grew initially in cross-section. The average cross-section of the gel fibrils reached a constant value after an initial growth period of ∼800 sec. Further increase in SAXS intensity could be attributed to the increase in the length of the gel fibrils. Photon correlation, on the other hand, clearly showed two relaxation modes in both the sol and the gel (∼1 hr after the quenching process) states: a fast cooperative diffusion mode which remained constant from the sol to the gel state after correction for the temperature dependence of solvent viscosity; and a slow mode that could be attributed to the self-diffusion of the “free” gelatin chains and aggregates. The slow mode contribution to the time correlation function was reduced from ∼40% in sol to ∼20% in gel signaling a decrease but not the elimination of “free” particles in the gel network. The decrease in the intensity contribution by the slow mode is, however, accompanied by a large increase in the characteristic line-width distribution.

scholarly journals Determination of the absorption cross-sections of higher order iodine oxides at 355 nm and 532 nm

2020 ◽  
Author(s):  
Thomas R. Lewis ◽  
Juan Carlos Gómez Martin ◽  
Mark A. Blitz ◽  
Carlos A. Cuevas ◽  
John M. C. Plane ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Atmospheric Chemistry ◽  
Absorption Cross Section ◽  
Absorption Cross ◽  
Time Resolved ◽  
Flight Mass Spectrometry ◽  
Iodine Oxides ◽  
Photo Ionization

Abstract. Iodine oxides (IxOy) play an important role in the atmospheric chemistry of iodine. They are initiators of new particle formation events in the coastal and polar boundary layer and act as iodine reservoirs in tropospheric ozone-depleting chemical cycles. Despite the importance of the aforementioned processes, the photochemistry of these molecules has not been studied in detail previously. Here, we report the first determination of the absorption cross sections of IxOy, x = 2, 3, 5, y = 1–12 at λ = 355 nm by combining pulsed laser photolysis of I2/O3 gas mixtures in air with time-resolved photo-ionization time-of-flight mass spectrometry, using NO2 actinometry for signal calibration. The oxides selected for absorption cross section determinations are those presenting the strongest signals in the mass spectra, where signals containing 4 iodine atoms are absent. The method is validated by measuring the absorption cross section of IO at 355 nm, σ355 nm, IO = (1.2 ± 0.1) ×  10–18 cm2, which is found to be in good agreement with the most recent literature. The results obtained are: σ355 nm, I2O3 

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