Self-Mode-Locking Investigation of High-Power Optically Pumped Semiconductor Laser Advisor: Yung Fu Chen Student: Yi Chun Lee Date: 2010/07/09 Solid-State Laser Physics Lab. NCTU Electrophysics Y.C. Lee 高功率光激發式半導體雷射之自鎖模研究

Outline 1. Introduction 1.1 Background and Motivation 1.2 OPSL V.S DPSSL 1.3 OPSL Technology 2. OPSL Experimental Results 2.1 OPSL Parameter Optimized 2.2 Spontaneous Mode-Locking of OPSL 2.3 Theoretical Simulation 3. Summary and Future Work NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

Flashlamp Pumped Double Frequency Nd:YAG Laser ~532nm Flashlamp Pumped Nd:YAG Laser ~1064nm Diode Pumped Double Frequency Nd:YVO4 Laser ~532nm Diode Pumped Double Frequency Nd:YAG Laser ~561nm Optical Pumped Semiconductor Laser ~577nm Diode Laser ~810nm 閉角型青光眼之小梁成型術 視網膜剝離、眼底止血 青光眼治療、眼底光凝結手術 白內障手術 眼底黃斑部病變 NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

Applications for OPSL Medical Field Life Science and Research Forensics Graphic Arts and Display Optically Pumped Semiconductor Laser NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

60fs NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

Polarizer Cr 4+ Crystal Output Coupler Flash Lamp 1064 nm Reflector Mirror Reflector Nd:YAG Rod 2 ns/div Flash lamp pumped passively Q- switched Nd:YAG laser Strange Phenomenon in Time Domain NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

Fiber-coupled nm 1030~1100 nm FP filter nm nm Laser output Yb doped double-clad fiber PM; clad/core: Dia. 250/30 μm (3m) NA >0.46 /<0.06 cavity R~4% 3x50 QWs Diode pumped passively Q-switched Yb-doped fiber laser 10 ns/div Strange Phenomenon in Time Domain NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

100 ns/div1 ns/div 2 ns/div Cw-pumped diffusion-bonded Nd:YVO 4 laser Cavity length ： 19 cm Cavity length ： 45 cm Nd:YVO4 Crystal Output Coupler Coupling Lens Diode Pumped Diffusion-Bonded Nd:YVO4 Laser 808nm Laser Diode Strange Phenomenon in Time Domain NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee 1064nm

Self-Mode-Locked Nd:YVO4 Laser 200 ps/div Stable CW mode locking and short pulse width NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee Output coupler Fiber coupled LD

DPSSL – Diode Pumped Solid State Laser 二極體激發式固態雷射 OPSL – Optically Pumped Semiconductor Laser 光激發式半導體雷射  In 1980s, the progress in the growth technology of semiconductor heterostructures developed the high-power diode laser pumped with a solid gain medium is so called diode-pumped solid-state (DPSS) lasers.  In 1997, M. Kuznetsov, F.Hakimi and A. Mooradian demonstrated the first optically-pumped semiconductor laser (OPSL). OPSL V.S DPSSL NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

△Ec△Ec △Ev△Ev EgEg E g well barrier The Mechanism of Stimulated Emission - Four-Level System in Solid-State Laser and Semiconductor Laser OPSL V.S DPSSL NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

OPSL Optically Pumped Semiconductor Laser Diode Pumped Solid State Laser DPSSL V.S OPSL V.S DPSSL NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

Semiconductor as Gain Medium - Substrate - Quantum Well - Bragg Mirror OPSL Technology NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

GaAs substrate based InP substrate based AlGaAs ( nm) InGaAs ( nm) GaInNAs ( μm) Wavelength ＞ 1.3μm OPSL Technology NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

Substrate Active region Cap layer x ….. 30 periods The Length of Quantum Well would be designed as 1/2 laser wavelength Laser Wavelength would slightly shifted according to quantum well design. OPSL Technology NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

Outline 1. Introduction 1.1 Background and Motivation 1.2 OPSL V.S DPSSL 1.3 OPSL Technology 2. OPSL Experimental Results 2.1 OPSL Parameter Optimized 2.2 Spontaneous Mode-Locking of OPSL 2.3 Theoretical Simulation 3. Summary and Future Work NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

Cavity Length NCTU Electrophysics Solid-State Laser Physics Lab. OPSL Optimized Pumping Source Semiconductor Gain Medium Y.C. Lee 1060 nm

OPSL Optimized OPSL Optimized by using Different Radius of Output Coupler Cavity Length NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee Focusing lens Semiconductor Gain Medium Output Coupler Laser Diode 1060 nm High speed photo-detector

ROC = 50mm Cavity Length = 30mm, Max Power ~7.4W Cavity Length ~ 50mm, Max Power ~7.03W ROC = 250mm Cavity Length = 25mm, Max Power ~7.8W Cavity Length = 50mm, Max Power ~8.0W Cavity Length = 100mm, Max Power ~ 7.8W ROC = 2000mm Cavity Length = 25mm, Max Power ~6.8W Cavity Length = 50mm, Max Power ~6.7W ROC = 250mm Cavity Length = 50mm, Max Power ~8.0W Different Radius of OC and Cavity Length. OPSL Optimized NCTU Electrophysics Solid-State Laser Physics Lab.

Spontaneous Mode-Locking of OPSL Mode-Lock Optimized 5ns/div Power Optimized 5ns/div NCTU Electrophysics Focusing lens Semiconductor Gain Medium Output Coupler Laser Diode 1060 nm Digital oscilloscope High speed photo-detector

Spontaneous Mode-Locking of OPSL ROC = 250mm Cavity Length ~ 250mm NCTU Electrophysics

5ns/div Power Optimized Mode-Lock Optimized Spontaneous Mode-Locking of OPSL ROC = 250mm Cavity Length ~ 250mm NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

Spontaneous Mode-Locking of OPSL ROC = 250mm Cavity Length = 187mm NCTU Electrophysics

5ns/div Power Optimized Mode-Lock Optimized Spontaneous Mode-Locking of OPSL ROC = 250mm Cavity Length = 187mm NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

Spontaneous Mode-Locking of OPSL ROC = 250mm Cavity Length = 125mm NCTU Electrophysics

2ns/div Power Optimized Mode-Lock Optimized Spontaneous Mode-Locking of OPSL ROC = 250mm Cavity Length = 125mm NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee 2ns/div

Spontaneous Mode-Locking of OPSL ROC = 250mm Cavity Length = 86mm NCTU Electrophysics

2ns/div Power Optimized Mode-Lock Optimized Spontaneous Mode-Locking of OPSL ROC = 250mm Cavity Length = 86mm NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

Spontaneous Mode-Locking of OPSL ROC = 250mm Cavity Length = 125mm NCTU Electrophysics Power Optimized 2ns/div Mode-Lock Optimized 2ns/div Fundamental Mode Solid-State Laser Physics Lab.

Spontaneous Mode-Locking of OPSL Scan the Beating to determine the distribution of high-order mode. NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee Focusing lens Semiconductor Gain Medium Output Coupler Laser Diode 1060 nm Digital oscilloscope High speed photo-detector

ns/div ns/div 3 Y.C. Lee

Frequency (GHz) Spectral power density (dBm) Spontaneous Mode-Locking of OPSL Longitudinal Frequency Transverse Frequency NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

Fundamental Mode High-Order Mode Detected Point 3 6 High-Order Mode Spontaneous Mode-Locking of OPSL NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

q 0 表示縱向模態的指標， l cav 代表有效的共振腔長， R 為曲率半徑。 NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee Theoretical Simulation

NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee Theoretical Simulation

NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee Theoretical Simulation

2ns/div NCTU Electrophysics Solid-State Laser Physics Lab. Experimental ResultsTheoretical Simulation Y.C. Lee

2ns/div NCTU Electrophysics Solid-State Laser Physics Lab. 2ns/div 4 4 Y.C. Lee 52ns/div

ns/div 10 2ns/div 11 2ns/div NCTU Electrophysics Solid-State Laser Physics Lab. 2ns/div8 8 Y.C. Lee

ns/div ns/div ns/div Y.C. Lee

Outline 1. Introduction 1.1 Background and Motivation 1.2 OPSL V.S DPSSL 1.3 OPSL Technology 2. OPSL Experimental Results 2.1 OPSL Parameter Optimized 2.2 Spontaneous Mode-Locking of OPSL 2.3 Theoretical Simulation 3. Summary and Future Work NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

Summary OPSL also discovered the spontaneous mode-locking phenomenon. The beating of the mode-locking output pulse trains are observed of transverse modes coupling. Theoretical simulation is matched to experimental results. 5ns/div NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

0/11/1 1/2 2/31/3 1/43/42/53/5 1/52/73/83/74/7 5/85/74/6 1/62/93/113/104/115/135/124/9 NCTU Electrophysics Solid-State Laser Physics Lab. Farey Tree Y.C. Lee Future Work

1:3 NCTU Electrophysics Solid-State Laser Physics Lab. Future Work Y.C. Lee

1:4 2ns/div NCTU Electrophysics Solid-State Laser Physics Lab. Future Work Y.C. Lee

2:5 NCTU Electrophysics Solid-State Laser Physics Lab. Future Work Y.C. Lee

5:12 NCTU Electrophysics Solid-State Laser Physics Lab. Future Work Y.C. Lee

5ns/div 7:17 12:29 NCTU Electrophysics Solid-State Laser Physics Lab. Future Work Y.C. Lee

Focusing lens Semiconductor Gain Medium Output Coupler Laser Diode 1060 nm Digital oscilloscope High speed photo-detector SESAM Future Work NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee

Thanks for your attention! NCTU Electrophysics Solid-State Laser Physics Lab. Y.C. Lee