Coherent Random Fiber Laser-Enabled Super-Resolution Spectroscopy

Abstract

Inspired by single-molecule localization microscopy, super-resolution spectroscopy has been achieved by sparse sampling in the spectral domain, where a light source capable of randomly emitting sparse peaks plays a crucial role. Due to the intrinsic feedback mechanism of disordered light scattering, random lasers can provide the desired emission characteristics that facilitate reconstructing the detailed spectral profiles of samples. Here, we propose an all-fiber-configured coherent random laser for spectral measurement to break the instrumental response limitation of spectral detection systems. The laser remains in a chaotic regime and exhibits self-modulating spectral behavior by introducing an elaborately designed spectral tailoring element inside the cavity. The statistical number and distribution of the random peaks over the emission spectrum can be manipulated by adjusting the pump power. In addition, the laser exhibits several attractive features, such as low pumping threshold, narrow-line-width lasing modes, flexible operating wavelength range, high optical signal-to-noise ratio, and easy compatibility with optical fiber systems. Using a low-resolution spectrograph, we experimentally demonstrate super-resolution spectrum reconstruction, obtaining a spectral enhancement of around 3.3. This work provides a powerful illumination source and realization method for high-resolution spectroscopy, which is an essential tool for future optical information applications.

Random fiber laser using a cascaded fiber loop mirror

“…The radio-frequency spectra show interesting phenomena due to the multiple F-P cavities formed in the CFLM, which is briefly discussed here and worth further investigating in the future. Compared with the recent work where 11 fiber reflectors with Au-film-coated facets are connected in series through flanges, 29 the CFLM based on fiber fusion operation should have better reusability for superresolution spectroscopy applications. The weak saturable absorption effect in each FLM, also known as a nonlinear optical loop mirror, 47 provides a platform for the analysis of cascaded effects for pulsating operation.…”

“…The chaotic spectrum has the same trend as other reported random media. 29,36 The multiple spikes may support several modes in the laser, and some of the modes may prevail in the mode competition and start lasing. Figure 1(c) shows the simulated spatial intensity distribution inside the 10-CFLM by the transfer matrix method.…”

“…28 A random Fabry-Pérot (F-P) cavity array based on Au-filmcoated fiber reflector is another choice for random lasing by light localization. 29 Although these artificial scattering media provide much fabrication flexibility, the requirement of specific expensive fabrication equipment hinders further application. Therefore, finding new cost-effective artificial scattering media with ease of fabrication would greatly facilitate the application of RFLs.…”

Generation of Narrow Modes in Random Raman Fiber Laser Based on Multimode Fiber

“…The random fiber lasers operating in the regime of generating narrow intermitting modes seem to be an attractive light source for super-resolution spectroscopy [30,31]. In this approach to high-resolution spectral measurements, the moderate resolution of a spectrum analyzer is significantly enhanced with repetitive measurements of the narrow-band irradiation source.…”

“…Since the performance of the method is largely determined by the quality of the random laser source, the proposed implementations are not of practical interest, since the low speed of mode switching requires a long data acquisition process. Thus, spectroscopy with a random fiber laser based on a random array of fiber Fabry-Perot cavities, with a small mode-switching rate, imposes minutes-long data collection [31]. From a practical point of view, to achieve the effective implementation of a high-resolution spectroscopy system, it is necessary to be able to match the frequencies of mode occurrence with the speed and range of operation of the spectrum analyzer used.…”