55  W  kilohertz-linewidth core- and in-band-pumped linearly polarized single-frequency fiber laser at 1950  nm

Abstract

Based on core- and in-band-pumped polarization-maintaining T m 3 + -doped single-cladding fiber (PM-TSF, the core diameter is 9 µm) by a 1610 nm fiber laser and a distributed Bragg reflector seed laser, a linearly polarized single-frequency fiber laser (LP-SFFL) at 1950 nm with an output power of 55.3 W and a laser linewidth of 6.95 kHz is demonstrated. The output beam qualities of M x 2 and M y 2 are measured to be 1.01 and 1.03, respectively. The slope efficiency with respect to the launched pump power is 71.0%, in comparison with a theoretical quantum efficiency of 82.6%. A polarization-extinction ratio of 19 dB and an optical signal-to-noise ratio of 58 dB are obtained from the 1950 nm LP-SFFL. To the best of our knowledge, to date, this is the highest power of 2.0 µm SFFL output directly from a strict single-mode active fiber. Our experiment offers a promising solution to the current limitations of the high-performance fiber lasers at 2.0 µm, which is particularly essential for coherent detection.

Promotion of Specific Single-Transverse-Mode Beam Characteristics for GaSb-Based Narrow Ridge Waveguide Lasers via Customized Parameter Design

“…Meanwhile, the ultra-high single-transverse-mode power and brightness obtained by Design B offer promising prospects in pumping fiber amplifiers and solid-state laser systems. In addition, the reduced lateral beam divergence observed for Design B allows the lateral bulk-coupling or the use of relatively simple and low-cost optics for coupling into commercial single-mode fibers, such as SM1950 or PM1950 [ 10 , 27 ], and photonic integrated circuit (PIC) applications [ 11 ].…”

“…The potential for higher output power with simultaneously good beam quality makes GaSb-based single-transverse-mode narrow ridge waveguide (RW) lasers ideally suited light sources for various scientific and commercial applications, such as pumping rare-earth-doped fiber amplifiers and solid-state lasers [ 8 – 10 ], seeding external cavity lasers [ 11 , 12 ], and nonlinear frequency conversion [ 13 ]. In addition, narrow RW structure is also widely employed in various laser devices, such as distributed-feedback (DFB) lasers [ 3 , 14 ], distributed Bragg reflector (DBR) lasers [ 15 , 16 ], superluminescent diodes (SLD) [ 5 , 17 ], semiconductor optical amplifiers (SOA) [ 18 ], and tapered lasers [ 19 ], owing to its ability to guarantee high transverse mode purity and stability, which enables the use of simple and low-cost optics for the focusing and coupling of these devices for further utilization.…”

“…For example, applications that perform beam transformations in complicated optical systems strictly require excellent beam quality, low astigmatism, and highly stable single-transverse-mode emission [ 9 , 12 ]. In contrast, pumping or coupling applications put higher emphasis on the promotion of optical output power and the compression of beam divergence [ 10 , 18 , 19 ]. Meanwhile, GaSb-based DFB, DBR, or SLD devices require relatively deep ridge etching to obtain a more substantial coupling effect of the grating or curved structure with the active layer [ 3 , 15 , 16 ].…”

Six-Wavelength-Switchable SLM Thulium-Doped Fiber Laser Enabled by Sampled FBGs and 3 × 3 Coupler Based Dual-Ring Compound Cavity Filter

“…Thus far, most works involving the 2 µm band focus on the 1900-2000 nm region, which is the high gain band of thulium-doped fibers (TDFs) [5][6][7][8]. However, SLM TDFLs in the 2050 nm band are still rarely reported.…”

Twelve-Wavelength-Switchable Thulium-Doped Fiber Laser With a Multimode Fiber Bragg Grating

“…To date, various TDFLs have been proposed, including the TDFL with switchable output [12], [13], TDFL with single-longitudinal-mode operation [14], [15], mode-locked TDFL [16], [17] and high power TDFL [18]. The TDFL with switchable output is extensively used in optical fiber sensing and wavelength routing networks due to its flexible lasing performance.…”