Optical Gain and Saturation Considerations of Organic Dyes

Abstract

A theoretical analysis of optical gain and saturation of organic dye lasers is presented. An analysis based on a solution o f the laser rate equations establishes a convenient method of optical gain measurement by internal fluorescence probing for low-gain system s, such as vapors of organic dyes. The concomitant limitations of high-gain system s (e.g. organic dyes in liquid solutions) of small-signal gain due to amplified spontaneous emission (ASE) and problems associated with gain saturation at high signal inputs are discussed in detail.

Amplified spontaneous emission from a liquid crystalline phase: anisotropic property and active modulation

“…This relationship was well represented by a one-pathway amplifier equation with α and β as fitting parameters gL = αI + ln( βI + 1),where g , L , and I are optical gain, longer side length of pump beam, and emission intensity, respectively. 39–41 From the fitting, the optical gain for the 1 wt% blend was estimated to be g = 8.2–16.9 cm −1 depending on the excitation fluence. This value is competitive to those of the typical high performance fluorescent dyes such as the coumarin family (7–50 cm −1 ), 42 rhodamine (∼10 cm −1 ), 43 diethylthiatricarbocyanine iodide (DTTC) (∼2.5 cm −1 ), 44 and the perylene family (∼4–53 cm −1 ).…”

“…Thus, the optical gain could be estimated by varying the optical length. [39][40][41] The obtained emission spectra of LC blends at variable lengths are shown in Fig. 2(b) and (c).…”