Stable and Widely Tunable Single-Longitudinal-Mode Dual-Wavelength Erbium-Doped Fiber Laser for Optical Beat Frequency Generation

All-polarization maintaining single-longitudinal-mode fiber laser with ultra-high OSNR, sub-KHz linewidth and extremely high stability

“…However, it is difficult to obtain SLM EDF ring laser with outstanding performance due to the unavoidable multi-longitudinal mode (MLM) oscillation or mode hopping, which is mainly caused by the homogeneous broadening of the EDF and the long cavity length of the EDFL [11]. To achieve stable SLM lasing for EDF ring lasers, researchers have utilized substantial techniques and optical components in the cavity, such as the multiple-ring compound resonator [7][8][12][13], the unpumped EDF-based saturable absorber (SA) filter [14], the Mazh-zehnder interferometer [15], the ultra-narrow pass-band filter [16], the phase shifted fiber Bragg grating (FBG) [17], the micro-ring resonator filter [18] and the micro-sphere filter [19].…”

“…In order to overcome the shortcomings of the above EDFLs, it is useful to employ the unpumped EDF-based SA filter in the EDF ring laser. An ultra-narrowband self-tracking filter can be established in the unpumped EDF to stabilize the SLM operation and narrow the linewidth of the EDFL under the specific standingwave condition [14]. In our previous work, we have designed and manufactured an SLM EDFL with excellent stability performance by cooperating a multiple-ring compound resonator with an SA filter [8].…”

Dual-frequency injection-locked continuous-wave near-infrared laser

“…Many types of dual-frequency lasers have been reported, including diode lasers with a periodic phasechange grating [1]; Ti:sapphire regenerative amplifier seeded with two cw lasers [2]; Ti:sapphire lasers implementing selfseeding technology or intracavity frequency-selectors, or both [3,4]; and fiber lasers with Bragg gratings and ultranarrow bandpass filters [5]. Above all, dual-frequency injection-locked (DFIL) lasers [6-9] are powerful tools, especially in the study of nonlinear optical processes in isolated atoms or molecules [10,11].…”

“…The advantage of dual-frequency lasers is that, in addition to their system compactness, mutual fine overlaps in time and space between radiations at two frequencies can be automatically realized, because the two-frequency radiation is produced by a single laser-resonator. Many types of dual-frequency lasers have been reported, including diode lasers with a periodic phase-change grating [1]; Ti:sapphire lasers implementing self-seeding technology or intracavity frequency-selectors, or both [2,3]; and fiber lasers with Bragg gratings and ultranarrow bandpass filters [4]. Above all, dual-frequency injection-locked (DFIL) lasers [5][6][7][8] are powerful tools, especially in the study of nonlinear optical processes in isolated atoms or molecules [9,10].…”

Single-/dual-wavelength switchable and tunable compound-cavity erbium-doped fiber laser with super-narrow linewidth

“…Due to the drastic mode competition induced by homogenous gain broadening effect in EDF, stable dual-wavelength SLM oscillation is not easy to achieve. In recent years, many researchers have reported different techniques to demonstrate stable dual-wavelength SLM EDFLs, such as a novel symmetrical fiber Bragg grating (FBG) structure as compact dual-wavelength laser cavity [2] , a reconfigurable dual-pass Mach-Zehnder interferometer (MZI) filter [18] , an unpumped polarization-maintaining EDF saturable absorber filter [19] , two superimposed FBGs and an in-line two-taper MZI filter [20] , a 70 cm long EDF loop attached to a microfiber coupler as wavelength filter [21] , a polarization-maintaining chirped Moiré FBG as ultra-narrow filter [22] , and a special U-bending apparatus based filter [23] . However, all of the techniques cannot achieve continuously tunable wavelength-spacing, switchable single-/dual-wavelength operation and narrow linewidth lasing simultaneously.…”