Terahertz light amplification by stimulated emission of radiation from optically pumped graphene

2011 ◽  
Author(s):  
Taiichi Otsuji ◽  
Stephane A. Boubanga Tombet ◽  
Silvia Chan ◽  
Akira Satou ◽  
Victor Ryzhii
Keyword(s):  
Stimulated Emission ◽  
Optically Pumped ◽  
Light Amplification

Terahertz light amplification by stimulated emission of radiation in optically pumped graphene

2012 ◽  
Vol 1451 ◽  
pp. 169-177
Author(s):  
Taiichi Otsuji ◽  
Stephane Boubanga Tombet ◽  
Akira Satou ◽  
S. Chan ◽  
Victor Ryzhii
Keyword(s):  
Delay Time ◽  
Emission Spectra ◽  
Optical Probe ◽  
Spectroscopic Studies ◽  
Stimulated Emission ◽  
Pulse Excitation ◽  
Optically Pumped ◽  
Optical Pump ◽  
Probe Delay ◽  
Light Amplification

ABSTRACTRecent advances in terahertz light amplification by stimulated emission of radiation in optically pumped graphene are reviewed. We present, within a picosecond time scale, fast relaxation and relatively slow recombination dynamics of photogenerated electrons and holes in an exfoliated graphene under infrared pulse excitation. We conduct time-domain spectroscopic studies using an optical pump and terahertz probe with an optical probe technique and show that graphene sheet amplifies an incoming terahertz field. The graphene emission spectral dependency on laser pumping intensity shows a threshold-like behavior, testifying to the occurrence of the negative conductivity and the population inversion. The emission spectra clearly narrow at a longer terahertz probe delay time, giving an evidence that the quasi-Fermi energy moves closer to the equilibrium at this longer terahertz probe delay time.

Ultraviolet Stimulated Emission From Optically Pumped AlGaN/AlGaN Multiple Quantum Wells on Pulsed Laterally Overgrown $a$-Plane GaN

2011 ◽  
Vol 4 (8) ◽  
pp. 082103 ◽  
Author(s):  
Mohamed Lachab ◽  
Krishnan Balakrishnan ◽  
Bin Zhang ◽  
Joe Dion ◽  
Qhalid Fareed ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Stimulated Emission ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Optically Pumped

Stimulated emission at 257 nm from optically-pumped AlGaN/AlN heterostructure on AlN substrate

2013 ◽  
Vol 210 (9) ◽  
pp. 1768-1770 ◽  
Author(s):  
Zachary Lochner ◽  
Xiao-Hang Li ◽  
Tsung-Ting Kao ◽  
Md. Mahbub Satter ◽  
Hee Jin Kim ◽  
...  
Keyword(s):  
Stimulated Emission ◽  
Optically Pumped

High-Power Low-Threshold Optically Pumped Type-ll Quantum-Well Lasers

1997 ◽  
Vol 484 ◽  
Author(s):  
Chih-Hsiang Lin ◽  
S. J. Murry ◽  
Rui Q. Yang ◽  
S. S. Pei ◽  
H. Q. Le ◽  
...  
Keyword(s):  
Quantum Well ◽  
Output Power ◽  
Optical Pumping ◽  
Internal Quantum Efficiency ◽  
Characteristic Temperature ◽  
Stimulated Emission ◽  
Free Carrier Absorption ◽  
Type Ii ◽  
Optically Pumped ◽  
Internal Loss

AbstractStimulated emission in InAs/InGaSb/InAs/AlSb type-II quantum-well (QW) lasers was observed up to room temperature at 4.5 μm, optically pumped by a pulsed 2-μm Tm:YAG laser. The absorbed threshold peak pump intensity was only 1.1 kW/cm2 at 300 K, with a characteristic temperature T0 of 61.6 K for temperatures up to 300 K. We will also study the effects of internal loss on the efficiency and output power for type-II QW lasers via optical pumping. Using a 0.98-μm InGaAs linear diode array, the devices exhibited an internal quantum efficiency of 67% at temperatures up to 190 K, and was capable of < 1. 1-W peak output power per facet in 6-μs pulses at 85 K. The internal loss of the devices exhibited an increase from 18 cm−1 near 70 K to ∼ 60–100 cm−1 near 180 K, which was possibly due to inter-valence band free carrier absorption.

Molecular Beam Epitaxy of Znl-x Cdx Se/ZnSe Heterostructures And Their Optical Properties

1991 ◽  
Vol 228 ◽  
Author(s):  
H. Luo ◽  
N. Samarth ◽  
J. K. Furdyna ◽  
H. Jeon ◽  
J. Ding ◽  
...  
Keyword(s):  
Optical Properties ◽  
Molecular Beam Epitaxy ◽  
Quantum Wells ◽  
Room Temperature ◽  
Molecular Beam ◽  
Stimulated Emission ◽  
Optically Pumped ◽  
Absorption Coefficients ◽  
Excitonic Absorption ◽  
Lasing Mechanism

ABSTRACTSuperlattices and quantum wells of Znl-xCdxSe/ZnSe, and heterostructures based on ZnSe/CdSe digital alloys have been grown by molecular beam epitaxy (MBE). Their optical properties were studied with particular emphasis on excitonic absorption and photopumped stimulated emission. Excitonic absorption is easily observable up to 400 K, and is characterized by extremely large absorption coefficients (α = 2×105cm−1). Optically pumped lasing action is obtained at room temperature with a typical threshold intensity of 100 kW/cm2. The lasing mechanism in these II-VI quantum wells appears to be quite different from that in the better studied III-V materials: in our case, the onset of stimulated emission occurs before the saturation of the excitonic absorption, and the stimulated emission occurs at an energy lower than that of the excitonic absorption.

Study of Near-Threshold Gain Mechanisms in MOCVD-Grown GaN Epilayers and InGaN/GaN Heterostructures

1999 ◽  
Vol 572 ◽  
Author(s):  
S. Bidnyk ◽  
T. J. Schmidt ◽  
B. D. Little ◽  
J. J. Song
Keyword(s):  
Quantum Wells ◽  
Stimulated Emission ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Optically Pumped ◽  
Electron Hole ◽  
Electron Hole Plasma ◽  
Narrow Emission ◽  
Threshold Gain ◽  
Near Threshold

ABSTRACTWe report the results of an experimental study on near-threshold gain mechanisms in optically pumped GaN epilayers and InGaN/GaN heterostructures at temperatures as high as 700 K. We show that the dominant near-threshold gain mechanism in GaN epilayers is inelastic excitonexciton scattering for temperatures below ∼ 150 K, characterized by band-filling phenomena and a relatively low stimulated emission (SE) threshold. An analysis of both the temperature dependence of the SE threshold and the relative shift between stimulated and band-edge related emission indicates electron-hole plasma is the dominant gain mechanism for temperatures exceeding 150 K. The dominant mechanism for SE in InGaN epilayers and InGaN/GaN multiple quantum wells was found to be the recombination of carriers localized at potential fluctuations resulting from nonuniform indium incorporation. The SE spectra from InGaN epilayers and multiple quantum wells were comprised of extremely narrow emission lines and no spectral broadening of the lines was observed as the temperature was raised from 10 K to over 550 K. Based on the presented results, we suggest a method for significantly reducing the carrier densities needed to achieve population inversion in GaN, allowing for the development of GaNactive-medium laser diodes.

Terahertz light amplification of stimulated emission of radiation in current-injection graphene channel transistor

2019 ◽  
Author(s):  
Stephane Boubanga-Tombet ◽  
Deepika Yadav ◽  
Takayuki Watanabe ◽  
Akira Satou ◽  
Wojciech Knap ◽  
...  
Keyword(s):  
Current Injection ◽  
Stimulated Emission ◽  
Light Amplification
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