temporal profiles for measuring threshold of random lasers pumped by ns pulses - laser profile measurement

Working threshold is an important parameter for evaluating cavity performance
Free Random laser
Here, TIME contour measurement is proposed as an alternative method for determining the threshold of a random laser based on surface plasma body element under ns pulse pump based on the analysis of delay time (
T delay)
And rise time (
T)
The transmitting signal.
The obvious and slight inflection points of t-delay and t-R curves with pump power density were observed as indicators of random laser thresholds and laser mode transitions, respectively.
The proposed method is the traditional method in frequency-
The domain of a random system with different gain lengths.
The demonstrated Time profile method is not limited by the spectrometer and can be used as a candidate for measuring the threshold of random lasers in ultra-fast optics, non-linear optics, and bio-optics
Compatible with photoelectric probes. Random lasers (RLs)
Based on the dielectric scattering of metal nanoparticles and surface plasma resonance, their interesting physical mechanism and potential application value have attracted wide attention.
Free imaging and information retrieval.
For the resonance scattering system, the working threshold is one of the most important physical parameters to characterize its performance.
Typically, the inflection point of the emission intensity and/or spectral line width with the variation of the pumping power density is used to determine the threshold of the random laser.
Probability of random laser with subrandom laser
Nano-peaks and l vy indices on emission curves are also used to define thresholds, respectively.
These methods mentioned above are emission spectra based on frequency domain and require a spectrometer.
In addition, the inherent random properties of random lasers mean intense fluctuations in the intensity, bandwidth, and peak position of the emission spectrum, especially near the threshold.
The fluctuation properties complicate the process of measuring random laser thresholds based on frequency domain spectra.
Therefore, even if there is no spectrometer, it is very necessary to have an alternative method to determine the threshold of a random laser.
Fortunately, the time distribution of the emission contains some valuable relaxation dynamics from excitation to ground state, such as the radiation composite life of the excitation sub and the light wave-
The process of material interaction: linear fluorescence and nonlinear excitation Emission.
For resonance scattering, TIME profile measurements are widely used to demonstrate the dynamic response of resonance scattering and the change in decay time with pump power density.
In particular, under the same pump energy, the theoretical and practical verification shows the transition of the time and spectral features of the emission (the threshold)
In the last report
However, there is no report on the threshold to track resonance based on the delay time relative to the pump pulse and the rising time in the time distribution of the emission curve.
In this work, on the basis of analyzing the delay time, an alternative method is proposed to determine the threshold of the surface plasma body element random laser based on ns pulses (
)
And rise time (
)
Time distribution varying with pump power density.
Dynamic behavior of four kinds of dye emission
Study RL-based systems using detectors and oscilloscope.
The evolution of the delay time relative to the pumping pulse and the rise time shows the general variation law with the pump power density, proving the obvious inflection point corresponding to the random laser threshold measured by the traditional frequency methoddomain.
More importantly, a slight change was also observed to demonstrate the transition of the random laser pattern.
The proposed time profile method can be used as a candidate method for measuring the threshold of dye random laser in the hyper-spectrum
Fast optical field.