Abstract
A simple, stable and inexpensive dual-output port widely tunable semiconductor optical amplifier (SOA)-based fiber compound-ring laser structure is demonstrated. This unique nested ring cavity enables high optical power to split into different branches where amplification and wavelength selection are achieved by using low-power SOAs and a tunable filter. Furthermore, two Sagnac loop mirrors, which are spliced at the two ends of the compound-ring cavity not only serve as variable reflectors but also channel the optical energy back to the same port without using any high optical power combiner. We propose and discuss how the demonstrated fiber compound-ring laser structure can be extended in order to achieve a high power fiber laser source by using low power optical components, such as N × N couplers and (N > 1) number of SOAs. A coherent beam-combining efficiency of over 98% for two parallel nested fiber ring resonators is achieved over the C-band tuning range of 30 nm. Optical signal-to-noise ratio (OSNR) of +45 dB, and optical power fluctuation of less than ±0.02 dB are measured over three hours at room temperature.
Highlights
Single-mode fiber resonators of different architectures such as linear [1], Fox-Smith [2], ring [3,4,5], and compound fiber ring [6,7,8,9] cavities have been theoretically and experimentally explored in designing and building various kinds of fiber laser sources with single-longitudinal mode operation for low and high optical power applications such as optical communication systems, and for scientific, medical, material processing and military purposes [10]
We demonstrate a novel technique for a coherent beam-combining method based on the passive phase-locking mechanism [56,57,58] of two C-band low power semiconductor optical amplifier (SOA)-based all-single-mode fiber compound-ring resonators by exploiting beam combining at 3-dB fiber couplers that connect two parallel merged ring cavities
In addition to using semiconductor optical amplifiers, the proposed compound-ring cavity does not contain any optical isolators or optical isolators, which can lead to the development of a simple and very high compact power scalable, adjustable and switchable laser source
Summary
Single-mode fiber resonators of different architectures such as linear [1], Fox-Smith [2], ring [3,4,5], and compound fiber ring [6,7,8,9] cavities have been theoretically and experimentally explored in designing and building various kinds of fiber laser sources with single-longitudinal mode operation for low and high optical power applications such as optical communication systems, and for scientific, medical, material processing and military purposes [10]. We demonstrate a novel technique for a coherent beam-combining method based on the passive phase-locking mechanism [56,57,58] of two C-band low power SOAs-based all-single-mode fiber compound-ring resonators by exploiting beam combining (i.e., interference) at 3-dB fiber couplers that connect two parallel merged ring cavities This is unlike previous work [59] where non-adjustable multimode fiber laser output formed by a high power and expensive power combiner with a multimode output fiber (i.e., low brightness) was replaced by two low power Sagnac loop mirrors to create a dual-output port all-single-mode fiber laser structure with switchable and adjustable output power. Wavelength tunability can benefit components several applications sensorsfilter andlow wavelength division multiplexer (WDM) optical communications [66] as well as biomedical imaging systems [67]
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