Tunable and Switchable Dual-Wavelength SLM Narrow-Linewidth Fiber Laser with a PMFBG-FP Filter Cascaded by Multi-Ring Cavity

Abstract

A single longitudinal mode (SLM) dual-wavelength switchable erbium-doped fiber laser (DW-EDFL) based on polarization-maintaining fiber Bragg grating Fabry–Perot cavity (PMFBG-FP) cascaded multiple sub-ring cavities (MSCs) is proposed. A PMFBG-FP with a narrow-band transmission peak and MSCs was implemented as an optical filter to achieve stable dual-wavelength laser output and guaranteed SLM status. By stretching the PMFBG, a highly stable dual-wavelength tunable output could be achieved with a maximum tuning interval of 0.17 nm. The optical signal-to-noise-ratio (OSNR) at dual-wavelength lasing was higher than 57 dB, and the optimal wavelength and power fluctuations within 0.5 h were 0.01 nm and 0.79 dB, respectively. Meanwhile, the measured linewidths of each wavelength were 1.55 kHz and 1.65 kHz, respectively. The measured polarization states of the two laser wavelengths were linear and orthogonal, with a degree of polarization (DOP) of nearly 100%.

Selectable and stable single-frequency fiber laser with flattened power range and sub-kHz linewidth output

“…Besides, the EDF based lasers also have the appearances of narrow linewidth, single-longitudinal-mode (SLM), long coherence length, low phase noise and high optical signal to noise ratio (OSNR) [5]. How to reach the SLM behavior of EDF laser is a critical issue, owing to the multilongitudinal-mode (MLM) fluctuation which is existed in fiber laser readily [6]. There are several reasons to cause the MLM fluctuation, such as the long fiber cavity length, homogeneous broadening of erbium and modehopping [7].…”

Bidirectional Single Longitudinal Mode Er-Doped Fiber Ring Laser Using a Bandpass Filter and Cascaded Fiber Ring Filter

“…Fiber ring filters have been widely used in unidirectional fiber ring lasers [15], [16], [17], [18], [19], [20], [21]. Fiber ring filters are mainly made of standard optical fiber couplers, with convenient material acquisition and low cost.…”