Manipulation of Random Lasing Action From Dye-Doped Liquid Crystals Infilling Two-Dimensional Confinement Single Core Capillary

Abstract

The experimental detail of a random lasing action from dye-doped nematic liquid crystals (LCs) inside single-core capillaries with a core diameter below 50 m was investigated. The resonant characteristics, including the number of emission spikes, the full width at half maximum (FWHM), and the estimated Q-factor, were shown to depend on the core diameter of a capillary. In contrast with a capillary with a larger core diameter and having various emission spikes, only three emission spikes were excited from a capillary with a 10-m core diameter, owing to the smaller effective area of the pump beam. However, the decrease in the amplitude of emission spikes and the broadening of the linewidth accompanying the higher lasing threshold from a capillary with a 50-m core diameter are attributed to the decrease in the pump fluence and the increase in the scattering loss, respectively. In this paper, a random laser (RL) with the shortest FWHM emission peak of about 0.47 nm and the highest Q-factor of about 1268 was generated from the capillary with a 20-m core diameter. By means of temperature adjustment, the emission spectra of the RL that is related to the birefringence and alignment ordering of the LC molecules inside a capillary with a 20-m core diameter can be effectively altered. Our experiments show that the RL, revealing adjustable output emission spectra, can be a promising device in using remote sensing applications.

Multi-Band Up-Converted Lasing Behavior in NaYF4:Yb/Er Nanocrystals

“…λ p and Δλ are sharp peak wavelength and FWHM, respectively. The Q factor of NaYF 4 :Yb,Er microcavity is about 2700, which is comparable with other random laser systems [ 43 , 46 , 47 ]. As a result, it is verified that NaYF 4 :Yb,Er NCs film supports ultrahigh Q coherent random laser microcavity with low threshold.…”

“…It is observed that there are plenty of NaYF 4 :Yb,Er NCs, which can satisfy the sufficient scattering between NCs and NCs to realize random lasing. Moreover, sharp peaks with FWHM less than 0.2 nm emerge from the emission spectrum when the excitation power larger than that of the threshold value, as shown in right inset of Figure 4 c. The FWHM of lasing peak is less than that in other reports [ 43 , 44 ]. The Q factor of the NaYF 4 :Yb,Er microcavity can be approximately defined as Q = λ p /Δλ [ 45 ].…”

Random lasing from cholesteric liquid crystal microspheres dispersed in glycerol

“…When some of the rays return to their starting positions under constructive interference, a closed-loop path (dashed line) will be formed and enable coherent light. If the amplification along such a loop patch exceeds the loss, laser emission will occur [11,24,25]. The random lasing obtained here was unpolarized.…”

Spectral selectivity in capillary dye lasers

“…Miniaturizing liquid dye lasers into a microfluidic device has many potential advantages such as compactness, easy maintenance, safe laser operation, accurate spatial mode control, and low threshold energy [3][4][5][6][7] with a wide range of applications including chemical and biological sensing [8,9]. Microfluidic fiber lasers have also appeared in optical fiber platform resulting in dye fiber lasers [10][11][12][13][14][15][16][17]. Fiber lasers based on capillary tubes and photonic crystal fibers filled with a dye solution were studied in detail by Vasdekis et al [10].…”