اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدEffect of local pumping on random laser modes
52
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We have developed a numerical method based on the transfer matrix to calculate the quasimodes and lasing modes in one-dimensional random systems. Depending on the relative magnitude of the localization length versus the system size, there are two regimes in which the quasimodes are distinct in spatial profile and frequency distribution. In the presence of uniform gain, the lasing modes have one-to-one correspondence to the quasimodes in both regimes. Local excitation may enhance the weight of a mode within the gain region due to local amplification, especially in a weakly scattering system.
قيم البحث
اقرأ أيضاً
Random lasers use radiative gain and multiple scatterers in disordered media to generate light amplification. In this study, we demonstrate a random laser based on diamond nanoneedles that act as scatterers in combination with fluorescent dye molecul
es that serve as a gain medium. Random lasers realized using diamond possess high spectral radiance with angle-free emission and thresholds of 0.16 mJ. The emission dependence on the pillar diameter and density is investigated, and optimum lasing conditions are measured for pillars with spacing and density of 336 nm and ~ 2.9x10^10 cm-2. Our results expand the application space of diamond as a material platform for practical, compact photonic devices and sensing applications.
We investigate the effects of two dimensional confinement on the lasing properties of a classical random laser system operating in the incoherent feedback (diffusive) regime. A suspension of 250nm rutile (TiO2) particles in a Rhodamine 6G solution wa
s inserted into the hollow core of a photonic crystal fiber (PCF) generating the first random fiber laser and a novel quasi-one-dimensional RL geometry. Comparison with similar systems in bulk format shows that the random fiber laser presents an efficiency that is at least two orders of magnitude higher.
Random lasing occurs as the result of a coherent optical feedback from multiple scattering centers. Here, we demonstrate that plasmonic gold nanostars are efficient light scattering centers, exhibiting strong field enhancement at their nanotips, whic
h assists a very narrow bandwidth and highly amplified coherent random lasing with a low lasing threshold. First, by embedding plasmonic gold nanostars in a rhodamine 6G dye gain medium, we observe a series of very narrow random lasing peaks with full-width at half-maximum ~ 0.8 nm. In contrast, free rhodamine 6G dye molecules exhibit only a single amplified spontaneous emission peak with a broader linewidth of 6 nm. The lasing threshold for the dye with gold nanostars is two times lower than that for a free dye. Furthermore, by coating the tip of a single-mode optical fiber with gold nanostars, we demonstrate a collection of random lasing signal through the fiber that can be easily guided and analyzed. Time-resolved measurements show a significant increase in the emission rate above the lasing threshold, indicating a stimulated emission process. Our study provides a method for generating random lasing in the nanoscale with low threshold values that can be easily collected and guided, which promise a range of potential applications in remote sensing, information processing, and on-chip coherent light sources.
We investigate the lasing modes in fully chaotic polymer microstadiums under optical pumping. The lasing modes are regularly spaced in frequency, and their amplitudes oscillate with frequency. Our numerical simulations reveal that the lasing modes ar
e multi-orbit scar modes. The interference of partial waves propagating along the constituent orbits results in local maxima of quality factor at certain frequencies. The observed modulation of lasing mode amplitude with frequency results from the variation of quality factor, which provides the direct evidence of wave interference effect in open chaotic microcavities.
We address the problem of achieving a random laser with a cloud of cold atoms, in which gain and scattering are provided by the same atoms. In this system, the elastic scattering cross-section is related to the complex atomic polarizability. As a con
sequence, the random laser threshold is expressed as a function of this polarizability, which can be fully determined by spectroscopic measurements. We apply this idea to experimentally evaluate the threshold of a random laser based on Raman gain between non-degenerate Zeeman states and find a critical optical thickness on the order of 200, which is within reach of state-of-the-art cold-atom experiments.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
