Modeling In-band Pumped kW Level High-Power Tm-Doped Fiber Lasers via Simulations

Mengmeng Tao; Xisheng Ye; Jingfeng Ye; Ting Yu; Zhao Quan; Yunfeng Qi; Guobin Feng; Weibiao Chen

doi:10.3788/CJL202249.0101019

Journals >Chinese Journal of Lasers >Volume 49 >Issue 1 >Page 0101019 > Article

Chinese Journal of Lasers
Vol. 49, Issue 1, 0101019 (2022)

Modeling In-band Pumped kW Level High-Power Tm-Doped Fiber Lasers via Simulations

Mengmeng Tao^1、2、**, Xisheng Ye^1、*, Jingfeng Ye², Ting Yu¹, Zhao Quan¹, Yunfeng Qi¹, Guobin Feng², and Weibiao Chen¹

Author Affiliations

¹Shaihai Key Laboratory of All Solid-State Laser and Applied Techniques, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China

²State Key Laboratory of Laser Interaction with Matter, Northwest Institute of Nuclear Technology, Xi’an, Shaanxi 710024, China

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DOI: 10.3788/CJL202249.0101019 Cite this Article Set citation alerts

Mengmeng Tao, Xisheng Ye, Jingfeng Ye, Ting Yu, Zhao Quan, Yunfeng Qi, Guobin Feng, Weibiao Chen. Modeling In-band Pumped kW Level High-Power Tm-Doped Fiber Lasers via Simulations[J]. Chinese Journal of Lasers, 2022, 49(1): 0101019 Copy Citation Text

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Distribution of the heat load for different laser systems at 1 kW output. (a) 793 nm cladding pump; (b) 1570 nm cladding pump; (c) 1910 nm core pump; (d) 1910 nm pedestal pump

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Fig. 2. Algorithm diagram for simulation of TMI threshold and outer cladding damage threshold

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Fig. 3. Pump absorption with a constant nominal total absorption. (a) Forward pump distribution; (b) total absorption of pump

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Fig. 4. Power limitation of Tm-doped fiber laser at 1570 nm pump

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Fig. 5. Power limitation of Tm-doped fiber laser at 1910 nm pump. (a) Core pump; (b) pedestal pump

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Parameter	Value	Parameter	Value
Core radius, r₁	12.5 μm	Inner cladding radius, r₂	125 μm
Pedestal radius, r_p	22.5 μm	Outer cladding radius, r₃	200 μm
Heat conductivity of the core and the inner cladding，k₁，k₂	1.38 W·m^－1·K^－1	Heat conductivity of the outer cladding, k₃	0.2 W·m^－1·K^－1
Absorption cross-section@1570 nm, σ_ap1570	2.0×10^－25 m^－3^[17,28]	Emission cross-section@1570 nm，σ_ep1570	0.096×10^－25 m^－3^[28]
Absorption cross-section@1910 nm, σ_ap1910	0.21×10^－25 m^－3^[17,26,28]	Emission cross-section@1910 nm, σ_ep1910	4.97×10^－25 m^－3^[28]
Absorption cross-section@2010 nm, σ_ap2010	0.03×10^－25 m^－3^[28]	Emission cross-section@2010 nm, σ_ep2010	2.56×10^－25 m^－3^[7,28]
Doping concentration of LC TDF, N_LC	14.5×10²⁵ m^－3	Doping concentration of HC TDF, N_HC	28.5×10²⁵ m^－3
Thermo-optic coefficient of silica, k	1.2×10^－5 K^－1	Lifetime of ³F₄ energy level, τ	500 μs ^[17]

Table 1. Parameters used in the simulation

Pump band	Laser configuration	Optimal TDF length /m	Slope efficiency /%	Quantum efficiency /%
793 nm	CP＋HC	5.0	64.0	162.2
793 nm	CP＋LC	11.0	54.4	137.9
1570 nm	CP＋HC	10.0	76.4	97.8
1570 nm	CP＋LC	17.8	75.2	96.3
1910 nm	CoP＋HC	2.6	94.3	99.2
	CoP＋LC	5.0	93.9	98.8
	PP＋HC	5.6	93.7	98.6
	PP＋LC	10.4	92.8	97.7

Table 2. Optimal gain fiber length and corresponding slope efficiency of different laser systems at 1 kW output

Pump band	Laser configuration	Pump /W	Absorbed pump /W	Heat /W	Ratio /%
793 nm	CP＋LC	1810	1808	808	80.8
1570 nm	CP＋LC	1335	1327	327	32.7
1910 nm	CoP＋LC	1067	1066	66	6.6
1910 nm	PP＋LC	1081	1078	78	7.8

Table 3. Power characteristics of different laser systems at 1 kW output

Pump band	Laser configuration	Average heat load /(W·m^－1)	Maximum temperature /℃@H₁		Maximum temperature /℃@H₂
Pump band	Laser configuration	Average heat load /(W·m^－1)	Core	Outer cladding	Core	Outer cladding
793 nm	CP＋HC	104.3	407.7	323.1	220.2	135.6
793 nm	CP＋LC	69.3	227.6	182.0	126.5	80.9
1570 nm	CP＋HC	30.1	141.6	114.6	81.8	54.7
1570 nm	CP＋LC	17.8	83.2	68.8	51.4	37.0
1910 nm	CoP＋HC	22.1	103.8	84.9	62.1	43.3
	CoP＋LC	12.5	63.9	53.7	41.3	31.1
	PP＋HC	11.1	61.1	51.6	39.9	30.3
	PP＋LC	6.8	41.7	36.3	29.8	24.4

Table 4. Thermal characteristics of different laser systems at 1 kW output

Parameter	Value	Parameter	Value
Peak gain of SRS，g_R^*	0.5×10^－13 m/W ^[13]	Peak gain of SBS，g_B	1.2×10^－11 m/W ^[36]
Linewidth of SBS gain，Δν_B	10.0 MHz ^[12]	Laser linewidth，Δν	1.0 GHz
Melting temperature of the core，T_M	1709.9 ℃ ^[12]	Damage temperature of the outer cladding，T_m	105.0 ℃ ^[12]
Coolant temperature，T_c	16.9 ℃ ^[13]	Average heat load of TDFL at TMI threshold， ${\bar{Q}}_{TDFL}$	136.0 W/m ^[18]
Signal gain, G	10.0 ^[13]	Optical damage limit，I_OD	35.0 W/μm²^[14]

Table 5. Parameters used in the estimation of power limit factors

Pump band	Laser configuration	SBS@1 GHz /kW	SRS /kW	TMI /kW	TL /kW	OCD /kW		OD /kW
Pump band	Laser configuration	SBS@1 GHz /kW	SRS /kW	TMI /kW	TL /kW	H₁	H₂	OD /kW
1570 nm	CP＋HC	14.7	41.7	4.4	165.0	2.4	6.3	12.7
1570 nm	CP＋LC	8.3	23.4	7.4	275.0	4.1	10.5	12.7
1910 nm	CoP＋HC	56.7	160.3	5.8	219.2	3.2	8.4	12.7
	CoP＋LC	29.5	83.3	10.5	392.2	5.8	15.0	12.7
	PP＋HC	26.3	74.4	11.3	389.0	6.3	16.2	12.7
	PP＋LC	14.2	40.1	18.2	626.1	10.1	26.1	12.7