Fundamentals of Ultrashort Pulse Laser and Its Applications

Xiaonong Zhu; Wenxia Bao

doi:10.3788/CJL201946.1200001

Journals >Chinese Journal of Lasers >Volume 46 >Issue 12 >Page 1200001 > Article

Chinese Journal of Lasers
Vol. 46, Issue 12, 1200001 (2019)

Fundamentals of Ultrashort Pulse Laser and Its Applications

Xiaonong Zhu^1,* and Wenxia Bao^1,3

Author Affiliations

¹Institute of Modern Optics, NanKai University, Tianjin, 300350, China

³AdValue Photonics Inc., Tucson, AZ 85706, USA

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DOI: 10.3788/CJL201946.1200001 Cite this Article Set citation alerts

Xiaonong Zhu, Wenxia Bao. Fundamentals of Ultrashort Pulse Laser and Its Applications[J]. Chinese Journal of Lasers, 2019, 46(12): 1200001 Copy Citation Text

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Normalized electric-field strength (dashed curve) and transient intensity (solid curve) of 15-fs chirp-free Gaussian laser pulse with central wavelength of 800 nm

Fig. 1. Normalized electric-field strength (dashed curve) and transient intensity (solid curve) of 15-fs chirp-free Gaussian laser pulse with central wavelength of 800 nm

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Fig. 2. Relationship between time- and frequency-domains of ultrashort laser pulses. Two domains form Fourier transform pairs

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Fig. 11. Approximate selection guide of wavelength and pulse duration in USP laser machining

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Fig. 12. Effect of pulse energy on actual ablation pulse duration (dotted line represents ablation threshold)

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Fig. 13. Learning map of ultrafast laser optics

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Laser parameter		[Unit], common unit	Relation
	Central wavelength, λ	[m], nm, μm
	Pulse duration, Δt	[s], ps, fs
	Average power, P	[W], mW, W, kW
	Pulse repetition rate, F	[Hz], kHz, MHz	Also known as PRR
Basic parameters	Bandwidth, Δλ(or spectral width, Δν)	[m], nm, μm	Δν=Δλ×(c/λ²) [Hz]
	Polarization ratio, PR	(unitless)
	Radius of laser beam, w	[m], mm, μm
	Laser beam circularity, C	(unitless)	w_x/w_y≤100%
	Beam divergence, θ	[rad], rad, mrad
	Beam quality factor, M²	(unitless)	M²=θ/(λ/πw)(≥1)
	Pulse energy, ΔE	[J], μJ, nJ	ΔE=P/F
	Peak power, P	[W], kW, MW	P=ΔE/Δt
Derived parameters	Pulse period, T	[s], ns	T=1/F
	Area of laser beam cross section, A	[m]², cm²	A=πw²
	Energy fluence, F	[J]/[m]², J/cm²	F=2×ΔE/A
	Peak intensity, I	[W]/[m]², W/cm²	I=p/A=F/Δt
	Time bandwidth product, TBP	(unitless)	T_BP=Δt×Δν
Quality parameters	Beam parameter product, BPP	[m][rad], mm mrad	B_PP=w×θ=(λ/π)×M²
	Pulse stability	(unitless), (p-p%) rms
	Beam pointing	[rad] /[℃], rad/℃

Table 1. Common technical parameters of ultrashort pulse laser

Laser			Item			Trumpf			Coherent	SP			PI			Huaray			Bellin			Huakuai			YSL
Picosecond infrared laser			Model			TruMicro5070			HyperRapidNX 1064-50	IceFyre1064-50			RGH-1064-48			Olive-1064-50			Amber IR			YPP-IR-30			PicoYL-100-100-100
			Wavelength /nm			1030			1064	1064			1064			1064			1064			1064			1030
			Average power /W			100			50	50@400 kHz			48@400 kHz			50@500 kHz			75@1MHz			30@100 kHz			100
			Pulse energy /μJ			250			220@200 kHz	200@200 kHz			420@100 kHz			200@200 kHz			250@300 kHz			200@100 kHz			100@100 ps
			Repetition rate /kHz			400-1000			200-1000	0.001-10000			100-2000			0.001-1000			0.001-1000			100-1000			100-1000
			Pulse duration /ps			<10			<15	<15			~10			<10			<15			<15			100-500
			RMS of pulseenergy stability			N/A			<1%	<1.5%			<2%			≤1%			<3%			<2%			<2%
			Pulse selection			N/A			√	√			√			√			√			√			√
			M²			<1.3			≤1.3	<1.3			≤1.3			≤1.3			<1.3			<1.3			<1.3
			Polarization ratio			N/A			>100∶1	>100∶1			>100∶1			>100∶1			>100∶1			>100∶1			N/A
Femtosecond infrared laser		Model			TruMico 5070Femto Edition			Monaco1035-80-40				Spirit1030-100			HR-Femto-IR-50-40			AxiniteIR-20			YPF-IR-20			FemtoYL^TM-100
		Wavelength /nm			1030			1035±5				1030±5			1035			1030			1030			030
		Averagepower /W			80			40@500 kHz				100@1 MHz			40@1 MHz			20@1 MHz			20			100
		Pulseenergy /μJ			200			80@500 kHz				100@1 MHz			40@1 MHz			30@500 kHz			50			200
		Repetitionrate /kHz			400-1000			0.001-1000				0.001-10000			100-5000			0.001-1000			50-500			25-5000
		Pulse duration /ps			<900			<350				<400			<350			<500			<500			~400
		RMS of pulseenergy stability			N/A			1.5%				2%			<2%			<3%			<3%			<2%
		Pulse selection			N/A			N/A				N/A			N/A			√			√			√
		M²			<1.3			<1.2				<1.2			≤1.3			<1.3			<1.3			<1.3
		Polarizationratio			N/A			>100∶1				>100∶1			>100∶1			>100∶1			>100∶1			N/A
Picosecond green laser	Model			TruMicro5270			Hyper RapidNX 532-25				RGH-532-20			Olive-532-15			Amber GR			YPP-GN-20			PicoYL-Green
	Wavelength /nm			515			532				532			532			532			532			515
	Average power /W			60			25@200 kHz				20@100 kHz			15@500 kHz			45@500 kHz			20@500 kHz			30
	Pulse energy /μJ			150			125@200 kHz				200@100 kHz			100@100 kHz			90@500 kHz			40@500 kHz			40
	Repetition rate /kHz			400-1000			200-1000				100-2000			0.001-1000			0.001-1000			400-1000			300-2500
	Pulse duration /ps			<10			<15				~7			<10			<15			<15			800
	RMS of pulseenergy stability			N/A			<2%				<2%			≤1.5%			<3%			<2%			<2%
	Pulse selection			N/A			√				√			√			√			√			√
	M²			<1.3			≤1.3				≤1.3			≤1.2			<1.3			<1.3			<1.3
	Polarization Ratio			N/A			>100∶1				>100∶1			>100∶1			>100∶1			>100∶1			N/A
Picosecond UV laser			Model			TruMicro5370			HyperRapidNX 355-15	IceFyre355-30			RGH-355-12			Olive-355-10			Amber UV			YPP-UV-10			PicoYL-UV
			Wavelength /nm			343			355	355			355			355			355			355			343
			Average power /W			30			15	30@500 kHz			12@100 kHz			10@500 kHz			30@700 kHz			15			15
			Pulse energy /μJ			75			75@200 kHz	60@500 kHz			120@100 kHz			60@100 kHz			42@700 kHz			30@500 kHz			30
			Repetition rate /kHz			400-1000			200-1000	0.001-3000			100-2000			0.001-1000			0.001-1000			400-1000			300-1200
			Pulse duration /ps			<10			<15	<15			~7			<10			<15			<15			800
			RMS of pulseenergy stability			N/A			<2%	<2%			<3%			≤1.5%			<3%			<5%			<2%
			Pulse selection			N/A			√	√			√			√			√			√			√
			M²			<1.3			≤1.3	<1.3			≤1.3			≤1.2			<1.3			<1.3			<1.3
			Polarization ratio			N/A			>100∶1	>100∶1			>100∶1			>100∶1			>100∶1			>100∶1			N/A