External (differential) quantum efficiency Number of additional photons emitted / number of additional electrons injected
|
|
- Rolf McGee
- 6 years ago
- Views:
Transcription
1 Semiconductor Lasers Comparison with LEDs The light emitted by a laser is generally more directional, more intense and has a narrower frequency distribution than light from an LED. The external efficiency of a laser is much greater than that of an LED. Light emitted from a laser is coherent. Light power output (P) LED-like Laser-like External (differential) quantum efficiency Number of additional photons emitted / number of additional electrons injected e hν ΔP ΔI Current applied to device (I) LASER Light Amplification by the Stimulated Emission of Radiation Need to understand the physics of stimulated emission
2 Consider a system with two electronic levels (1 and 2). There are 3 possible electron-photon processes photon E photon Absorption a photon of energy E excites an electron from level 1 to level 2. The photon is destroyed. Spontaneous emission An electron in level 2 relaxes to level 1. A photon of energy E is created. The relaxation is a random process the created photon has a random phase and is emitted in a random direction. 2 1 Stimulated emission An electron in level 2 is stimulated into relaxing to level 1 by a passing photon. The new photon has the same phase, energy and direction as the original photon. Absorption causes a beam of light (stream of photons) to be attenuated as it passes through a material. Stimulated emission causes a beam of light to be amplified as it passes through a material.
3 Intensity (I) Absorption Intensity (I) Stimulated emission Distance (x) Distance (x) In a real system a mixture of absorption and stimulated emission will occur (spontaneous emission can be ignored once stimulated emission becomes important as electrons will relax by stimulated emission before they have time to relax spontaneously). For laser action to occur, overall amplification is required i.e. STIMULATED EMISSION > ABSORPTION If there are n 1 electrons in level 1 and n 2 electrons in level 2: Strength of absorption = A abs n 1 Strength of stimulated emission = A stim n 2 (can be shown that A abs =A stim ) Therefore laser action requires n 2 > n 1
4 Population Inversion For thermal equilibrium n n 2 = E kt < 1 e 1 Hence n 2 > n 1 (a population inversion) is only possible under non-equilibrium conditions In a semiconductor a population inversion can be obtained if there are a large number of occupied states (electrons) in the conduction band and unoccupied states (holes) in the valence band. electrons holes Such a condition is not easily obtained in a bulk semiconductor but can be created and maintained in a forward biased p-n junction: p-type A large density of electrons (holes) are injected into the p-type (n-type) material to create the population inversion n-type
5 Laser construction Require a material in which a population inversion is maintained (this requires constant energy input). Generally require a very long optical path length through material for sufficient amplification. Hence place material between 2 mirrors so that the light can keep passing through the material: Lasing material High refl. mirror Energy in to maintain population inversion Partially reflecting mirror allows some light to escape from the cavity Semiconductor laser: Current flow Coherent radiation Optically flat parallel faces
6 Variation of gain with carrier density and current cb vb Low current and carrier density (n) Absorption > stimulated emission High current and carrier density (n) Absorption < stimulated emission g GAIN LOSS n th (I th ) n (or I) n trans (I trans ) Point at which line passes through zero (g=0) is known as TRANSPARENCY - Gain balances absorption - Light travelling along the cavity is neither absorbed or amplified Lasing does not occur at transparency. A positive non-zero gain is required to overcome losses in the system. Lasing occurs at g=g th where g th is the threshold gain (occurs when I=I th, n=n th )
7 As light travels along the cavity it is amplified by the active region at a rate g per unit length. However, there will be some losses due to imperfections in the material, which scatter the light, and also by absorption of the part of the light field which extends beyond the active region. We describe these losses by α. Hence the amplification per unit length is (g-α) When light hits an end mirror only a fraction R, where R is the mirror reflectivity, is reflected back into the cavity the remainder escapes After passing along a cavity of length L, the light is amplified by e ( g α )L But only a fraction R is returned to the cavity. Hence, if the initial light intensity is I 0 after traversing one cavity length and hitting one mirror, the new intensity is I 1 = 0 e ( g I α ) L R Three cases.
8 1. I 1 < I ( g α ) L 0 e R < 1 I 0 L L L TOTAL LOSSES EXCEED GAIN NO LASING 2. I 1 > I ( g α ) L 0 e R > 1 L L L I 0 GAIN EXCEEDS TOTAL LOSS LIGHT LEVEL INCREASES INDEFINITELY PHYSICALLY IMPOSSIBLE 3. I 1 = I ( g α ) L 0 e R = 1 L L L I 0 GAIN EQUALS TOTAL LOSS CONDITION FOR LASING TO OCCUR
9 Lasing condition: e ( g α ) L R = 1 ( g α) L 1 = ln R g th 1 1 = α + ln L R g th is the gain required to achieve lasing. Known as the threshold gain. Result shows that g th increases as cavity length decreases.
10 What happens to the carrier density at and above threshold? At threshold, carrier density is just sufficient so that the resultant gain equals all losses and lasing starts (g=g th ) If the carrier density increased as current increased further then gain would increase above g th (case 2 above) this is physically impossible The gain of a laser can never exceed g th. This implies that the carrier density can never exceed the threshold value n th. Above threshold, both g and n are clamped (or saturate) to their threshold values g th and n th : n th g th n g n or g I th I
11 Water analogy I/eV Current leakage ηi G I gen = ev Overflow R st R L n th R nr R sp Water level has reached the overflow and the depth of water (and hence escape processes) is clamped to a value n th. Overflow provides an infinitely large escape path. All additional water added to the tank leaves via the overflow. Real Device At threshold n and g clamp to their threshold values Because carrier loss processes (spontaneous emission, leakage, non-radiative recombination) have rates which are a function of n these processes must also clamp / saturate at threshold Therefore, above threshold carrier loss mechanisms no longer increase Stimulated emission is the only process which can continue to increase All additional carriers injected into the active region must produce a photon by stimulated emission.
12 External efficiency above threshold Above threshold loss mechanisms are clamped to their threshold values Above threshold additional carriers injected into the active region result in photons produced by stimulated emission
LASER. Light Amplification by Stimulated Emission of Radiation
LASER Light Amplification by Stimulated Emission of Radiation Laser Fundamentals The light emitted from a laser is monochromatic, that is, it is of one color/wavelength. In contrast, ordinary white light
More informationPaper Review. Special Topics in Optical Engineering II (15/1) Minkyu Kim. IEEE Journal of Quantum Electronics, Feb 1985
Paper Review IEEE Journal of Quantum Electronics, Feb 1985 Contents Semiconductor laser review High speed semiconductor laser Parasitic elements limitations Intermodulation products Intensity noise Large
More informationSignal regeneration - optical amplifiers
Signal regeneration - optical amplifiers In any atom or solid, the state of the electrons can change by: 1) Stimulated absorption - in the presence of a light wave, a photon is absorbed, the electron is
More informationPhotonic Devices. Light absorption and emission. Transitions between discrete states
Light absorption and emission Photonic Devices Transitions between discrete states Transition rate determined by the two states: Fermi s golden rule Absorption and emission of a semiconductor Vertical
More informationFIBER OPTICS. Prof. R.K. Shevgaonkar. Department of Electrical Engineering. Indian Institute of Technology, Bombay. Lecture: 17.
FIBER OPTICS Prof. R.K. Shevgaonkar Department of Electrical Engineering Indian Institute of Technology, Bombay Lecture: 17 Optical Sources- Introduction to LASER Fiber Optics, Prof. R.K. Shevgaonkar,
More informationLaser Basics. What happens when light (or photon) interact with a matter? Assume photon energy is compatible with energy transition levels.
What happens when light (or photon) interact with a matter? Assume photon energy is compatible with energy transition levels. Electron energy levels in an hydrogen atom n=5 n=4 - + n=3 n=2 13.6 = [ev]
More informationChemistry Instrumental Analysis Lecture 5. Chem 4631
Chemistry 4631 Instrumental Analysis Lecture 5 Light Amplification by Stimulated Emission of Radiation High Intensities Narrow Bandwidths Coherent Outputs Applications CD/DVD Readers Fiber Optics Spectroscopy
More informationChapter-4 Stimulated emission devices LASERS
Semiconductor Laser Diodes Chapter-4 Stimulated emission devices LASERS The Road Ahead Lasers Basic Principles Applications Gas Lasers Semiconductor Lasers Semiconductor Lasers in Optical Networks Improvement
More informationStimulated Emission Devices: LASERS
Stimulated Emission Devices: LASERS 1. Stimulated Emission and Photon Amplification E 2 E 2 E 2 hυ hυ hυ In hυ Out hυ E 1 E 1 E 1 (a) Absorption (b) Spontaneous emission (c) Stimulated emission The Principle
More informationLASERS. Dr D. Arun Kumar Assistant Professor Department of Physical Sciences Bannari Amman Institute of Technology Sathyamangalam
LASERS Dr D. Arun Kumar Assistant Professor Department of Physical Sciences Bannari Amman Institute of Technology Sathyamangalam General Objective To understand the principle, characteristics and types
More information(b) Spontaneous emission. Absorption, spontaneous (random photon) emission and stimulated emission.
Lecture 10 Stimulated Emission Devices Lasers Stimulated emission and light amplification Einstein coefficients Optical fiber amplifiers Gas laser and He-Ne Laser The output spectrum of a gas laser Laser
More informationLASER. Light Amplification by Stimulated Emission of Radiation
LASER Light Amplification by Stimulated Emission of Radiation Energy Level, Definitions The valence band is the highest filled band The conduction band is the next higher empty band The energy gap has
More informationLaser Types Two main types depending on time operation Continuous Wave (CW) Pulsed operation Pulsed is easier, CW more useful
What Makes a Laser Light Amplification by Stimulated Emission of Radiation Main Requirements of the Laser Laser Gain Medium (provides the light amplification) Optical Resonator Cavity (greatly increase
More informationIntroduction Fundamentals of laser Types of lasers Semiconductor lasers
Introduction Fundamentals of laser Types of lasers Semiconductor lasers Is it Light Amplification and Stimulated Emission Radiation? No. So what if I know an acronym? What exactly is Light Amplification
More informationIntroduction to Sources: Radiative Processes and Population Inversion in Atoms, Molecules, and Semiconductors Atoms and Molecules
OPTI 500 DEF, Spring 2012, Lecture 2 Introduction to Sources: Radiative Processes and Population Inversion in Atoms, Molecules, and Semiconductors Atoms and Molecules Energy Levels Every atom or molecule
More informationLASERS. Amplifiers: Broad-band communications (avoid down-conversion)
L- LASERS Representative applications: Amplifiers: Broad-band communications (avoid down-conversion) Oscillators: Blasting: Energy States: Hydrogen atom Frequency/distance reference, local oscillators,
More informationChapter 2 Optical Transitions
Chapter 2 Optical Transitions 2.1 Introduction Among energy states, the state with the lowest energy is most stable. Therefore, the electrons in semiconductors tend to stay in low energy states. If they
More informationStimulated Emission. Electrons can absorb photons from medium. Accelerated electrons emit light to return their ground state
Lecture 15 Stimulated Emission Devices- Lasers Stimulated emission and light amplification Einstein coefficients Optical fiber amplifiers Gas laser and He-Ne Laser The output spectrum of a gas laser Laser
More informationWhat Makes a Laser Light Amplification by Stimulated Emission of Radiation Main Requirements of the Laser Laser Gain Medium (provides the light
What Makes a Laser Light Amplification by Stimulated Emission of Radiation Main Requirements of the Laser Laser Gain Medium (provides the light amplification) Optical Resonator Cavity (greatly increase
More information22. Lasers. Stimulated Emission: Gain. Population Inversion. Rate equation analysis. Two-level, three-level, and four-level systems
. Lasers Stimulated Emission: Gain Population Inversion Rate equation analysis Two-level, three-level, and four-level systems What is a laser? LASER: Light Amplification by Stimulated Emission of Radiation
More informationFIBER OPTICS. Prof. R.K. Shevgaonkar. Department of Electrical Engineering. Indian Institute of Technology, Bombay. Lecture: 15. Optical Sources-LASER
FIBER OPTICS Prof. R.K. Shevgaonkar Department of Electrical Engineering Indian Institute of Technology, Bombay Lecture: 15 Optical Sources-LASER Fiber Optics, Prof. R.K. Shevgaonkar, Dept. of Electrical
More informationChapter 5. Semiconductor Laser
Chapter 5 Semiconductor Laser 5.0 Introduction Laser is an acronym for light amplification by stimulated emission of radiation. Albert Einstein in 1917 showed that the process of stimulated emission must
More informationρ ρ LED access resistances d A W d s n s p p p W the output window size p-layer d p series access resistance d n n-layer series access resistance
LED access resistances W the output window size p-layer series access resistance d p n-layer series access resistance d n The n-layer series access resistance R = ρ s n where the resistivity of the n-layer
More informationOther Devices from p-n junctions
Memory (5/7 -- Glenn Alers) Other Devices from p-n junctions Electron to Photon conversion devices LEDs and SSL (5/5) Lasers (5/5) Solid State Lighting (5/5) Photon to electron conversion devices Photodectors
More informationLaser Diodes. Revised: 3/14/14 14: , Henry Zmuda Set 6a Laser Diodes 1
Laser Diodes Revised: 3/14/14 14:03 2014, Henry Zmuda Set 6a Laser Diodes 1 Semiconductor Lasers The simplest laser of all. 2014, Henry Zmuda Set 6a Laser Diodes 2 Semiconductor Lasers 1. Homojunction
More information6. Light emitting devices
6. Light emitting devices 6. The light emitting diode 6.. Introduction A light emitting diode consist of a p-n diode which is designed so that radiative recombination dominates. Homojunction p-n diodes,
More informationAdvanced Optical Communications Prof. R. K. Shevgaonkar Department of Electrical Engineering Indian Institute of Technology, Bombay
Advanced Optical Communications Prof. R. K. Shevgaonkar Department of Electrical Engineering Indian Institute of Technology, Bombay Lecture No. # 15 Laser - I In the last lecture, we discussed various
More informationOptoelectronics ELEC-E3210
Optoelectronics ELEC-E3210 Lecture 3 Spring 2017 Semiconductor lasers I Outline 1 Introduction 2 The Fabry-Pérot laser 3 Transparency and threshold current 4 Heterostructure laser 5 Power output and linewidth
More informationChapter 13. Phys 322 Lecture 34. Modern optics
Chapter 13 Phys 3 Lecture 34 Modern optics Blackbodies and Lasers* Blackbodies Stimulated Emission Gain and Inversion The Laser Four-level System Threshold Some lasers Pump Fast decay Laser Fast decay
More informationEECE 4646 Optics for Engineers. Lecture 17
C 4646 Optics for ngineers Lecture 7 9 March, 00 Spontaneous mission Rate BFOR MISSION DURING MISSION AFTR MISSION electron hν hν The rate of spontaneous emission r sp can be written as: A f r sp A f[
More informationBasic Principles of Light Emission in Semiconductors
Basic Principles of Light Emission in Semiconductors Class: Integrated Photonic Devices Time: Fri. 8:00am ~ 11:00am. Classroom: 資電 06 Lecturer: Prof. 李明昌 (Ming-Chang Lee) Model for Light Generation and
More informationLaser Types Two main types depending on time operation Continuous Wave (CW) Pulsed operation Pulsed is easier, CW more useful
Main Requirements of the Laser Optical Resonator Cavity Laser Gain Medium of 2, 3 or 4 level types in the Cavity Sufficient means of Excitation (called pumping) eg. light, current, chemical reaction Population
More informationStimulated Emission. ! Electrons can absorb photons from medium. ! Accelerated electrons emit light to return their ground state
Lecture 15 Stimulated Emission Devices- Lasers! Stimulated emission and light amplification! Einstein coefficients! Optical fiber amplifiers! Gas laser and He-Ne Laser! The output spectrum of a gas laser!
More informationCourse overview. Me: Dr Luke Wilson. The course: Physics and applications of semiconductors. Office: E17 open door policy
Course overview Me: Dr Luke Wilson Office: E17 open door policy email: luke.wilson@sheffield.ac.uk The course: Physics and applications of semiconductors 10 lectures aim is to allow time for at least one
More informationStudy on Quantum Dot Lasers and their advantages
Study on Quantum Dot Lasers and their advantages Tae Woo Kim Electrical and Computer Engineering University of Illinois, Urbana Champaign Abstract Basic ideas for understanding a Quantum Dot Laser were
More informationEE 6313 Homework Assignments
EE 6313 Homework Assignments 1. Homework I: Chapter 1: 1.2, 1.5, 1.7, 1.10, 1.12 [Lattice constant only] (Due Sept. 1, 2009). 2. Homework II: Chapter 1, 2: 1.17, 2.1 (a, c) (k = π/a at zone edge), 2.3
More informationPHYSICS. The Probability of Occurrence of Absorption from state 1 to state 2 is proportional to the energy density u(v)..
ABSORPTION of RADIATION : PHYSICS The Probability of Occurrence of Absorption from state 1 to state 2 is proportional to the energy density u(v).. of the radiation > P12 = B12 u(v) hv E2 E1 Where as, the
More informationEE 472 Solutions to some chapter 4 problems
EE 472 Solutions to some chapter 4 problems 4.4. Erbium doped fiber amplifier An EDFA is pumped at 1480 nm. N1 and N2 are the concentrations of Er 3+ at the levels E 1 and E 2 respectively as shown in
More informationMs. Monika Srivastava Doctoral Scholar, AMR Group of Dr. Anurag Srivastava ABV-IIITM, Gwalior
By Ms. Monika Srivastava Doctoral Scholar, AMR Group of Dr. Anurag Srivastava ABV-IIITM, Gwalior Unit 2 Laser acronym Laser Vs ordinary light Characteristics of lasers Different processes involved in lasers
More informationChapter9. Amplification of light. Lasers Part 2
Chapter9. Amplification of light. Lasers Part 06... Changhee Lee School of Electrical and Computer Engineering Seoul National Univ. chlee7@snu.ac.kr /9 9. Stimulated emission and thermal radiation The
More informationAssignment 6. Solution: Assumptions - Momentum is conserved, light holes are ignored. Diagram: a) Using Eq a Verdeyen,
Assignment 6 Solution: Assumptions - Momentum is conserved, light holes are ignored. Diagram: a) Using Eq..4.5a Verdeyen, ΔE c = E 2 E c = Using Eq..4.5b Verdeyen, ΔE v = E v E = b) Using Eq.2.9 Verdeyen,
More information- Outline. Chapter 4 Optical Source. 4.1 Semiconductor physics
Chapter 4 Optical Source - Outline 4.1 Semiconductor physics - Energy band - Intrinsic and Extrinsic Material - pn Junctions - Direct and Indirect Band Gaps 4. Light Emitting Diodes (LED) - LED structure
More informationLASER. Challenging MCQ questions by The Physics Cafe. Compiled and selected by The Physics Cafe
LSER hallenging MQ questions by The Physics afe ompiled and selected by The Physics afe www.thephysicsafe.com www.pmc.sg 1 laser point creates a spot on a screen as it reflects 70% of the light striking
More informationS. Blair February 15,
S Blair February 15, 2012 66 32 Laser Diodes A semiconductor laser diode is basically an LED structure with mirrors for optical feedback This feedback causes photons to retrace their path back through
More informationUnit-2 LASER. Syllabus: Properties of lasers, types of lasers, derivation of Einstein A & B Coefficients, Working He-Ne and Ruby lasers.
Unit-2 LASER Syllabus: Properties of lasers, types of lasers, derivation of Einstein A & B Coefficients, Working He-Ne and Ruby lasers. Page 1 LASER: The word LASER is acronym for light amplification by
More informationLasers E 6 E 4 E 3 E 2 E 1
Lasers Laser is an acronym for light amplification by stimulated emission of radiation. Here the process of stimulated emission is used to amplify light radiation. Spontaneous emission: When energy is
More informationWhat are Lasers? Light Amplification by Stimulated Emission of Radiation LASER Light emitted at very narrow wavelength bands (monochromatic) Light
What are Lasers? What are Lasers? Light Amplification by Stimulated Emission of Radiation LASER Light emitted at very narrow wavelength bands (monochromatic) Light emitted in a directed beam Light is coherenent
More informationMTLE-6120: Advanced Electronic Properties of Materials. Semiconductor p-n junction diodes. Reading: Kasap ,
MTLE-6120: Advanced Electronic Properties of Materials 1 Semiconductor p-n junction diodes Reading: Kasap 6.1-6.5, 6.9-6.12 Metal-semiconductor contact potential 2 p-type n-type p-type n-type Same semiconductor
More informationPHYSICS nd TERM Outline Notes (continued)
PHYSICS 2800 2 nd TERM Outline Notes (continued) Section 6. Optical Properties (see also textbook, chapter 15) This section will be concerned with how electromagnetic radiation (visible light, in particular)
More informationPhotonics and Optical Communication
Photonics and Optical Communication (Course Number 300352) Spring 2007 Optical Source Dr. Dietmar Knipp Assistant Professor of Electrical Engineering http://www.faculty.iu-bremen.de/dknipp/ 1 Photonics
More informationWhat do we study and do?
What do we study and do? Light comes from electrons transitioning from higher energy to lower energy levels. Wave-particle nature of light Wave nature: refraction, diffraction, interference (labs) Particle
More informationWhat are Lasers? Light Amplification by Stimulated Emission of Radiation LASER Light emitted at very narrow wavelength bands (monochromatic) Light
What are Lasers? What are Lasers? Light Amplification by Stimulated Emission of Radiation LASER Light emitted at very narrow wavelength bands (monochromatic) Light emitted in a directed beam Light is coherenent
More informationIn a metal, how does the probability distribution of an electron look like at absolute zero?
1 Lecture 6 Laser 2 In a metal, how does the probability distribution of an electron look like at absolute zero? 3 (Atom) Energy Levels For atoms, I draw a lower horizontal to indicate its lowest energy
More information-I (PH 6151) UNIT-V PHOTONICS AND FIBRE OPTICS
Engineering Physics -I (PH 6151) UNIT-V PHOTONICS AND FIBRE OPTICS Syllabus: Lasers Spontaneous and stimulated emission Population Inversion -Einstein s co-efficient (Derivation)- types of lasers-nd-yag,co
More informationInternal Efficiency of Semiconductor Lasers With a Quantum-Confined Active Region
404 IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 39, NO. 3, MARCH 2003 Internal Efficiency of Semiconductor Lasers With a Quantum-Confined Active Region Levon V. Asryan, Serge Luryi, Fellow, IEEE, and Robert
More information5 Quantum Wells. 1. Use a Multimeter to test the resistance of your laser; Record the resistance for both polarities.
Measurement Lab 0: Resistance The Diode laser is basically a diode junction. Same as all the other semiconductor diode junctions, e should be able to see difference in resistance for different polarities.
More informationPopulation inversion occurs when there are more atoms in the excited state than in the ground state. This is achieved through the following:
Lasers and SemiconductorsTutorial Lasers 1. Fill in the table the differences between spontaneous emission and stimulated emission in atoms: External stimulus Direction of emission Phase & coherence of
More informationHigh Power Diode Lasers
Lecture 10/1 High Power Diode Lasers Low Power Lasers (below tenth of mw) - Laser as a telecom transmitter; - Laser as a spectroscopic sensor; - Laser as a medical diagnostic tool; - Laser as a write-read
More informationA system of two lenses is achromatic when the separation between them is
L e c t u r e 1 5 1 Eyepieces Single eye lens in a telescope / microscope produces spherical and chromatic aberrations. The field of view is also narrow. The eye lens is replaced by a system of lenses
More informationQuantum Electronics Laser Physics. Chapter 5. The Laser Amplifier
Quantum Electronics Laser Physics Chapter 5. The Laser Amplifier 1 The laser amplifier 5.1 Amplifier Gain 5.2 Amplifier Bandwidth 5.3 Amplifier Phase-Shift 5.4 Amplifier Power source and rate equations
More information3.1 Absorption and Transparency
3.1 Absorption and Transparency 3.1.1 Optical Devices (definitions) 3.1.2 Photon and Semiconductor Interactions 3.1.3 Photon Intensity 3.1.4 Absorption 3.1 Absorption and Transparency Objective 1: Recall
More informationFigure 1 Relaxation processes within an excited state or the ground state.
Excited State Processes and Application to Lasers The technology of the laser (Light Amplified by Stimulated Emission of Radiation) was developed in the early 1960s. The technology is based on an understanding
More informationReview of Optical Properties of Materials
Review of Optical Properties of Materials Review of optics Absorption in semiconductors: qualitative discussion Derivation of Optical Absorption Coefficient in Direct Semiconductors Photons When dealing
More informationLecture 15: Optoelectronic devices: Introduction
Lecture 15: Optoelectronic devices: Introduction Contents 1 Optical absorption 1 1.1 Absorption coefficient....................... 2 2 Optical recombination 5 3 Recombination and carrier lifetime 6 3.1
More informationLuminescence Process
Luminescence Process The absorption and the emission are related to each other and they are described by two terms which are complex conjugate of each other in the interaction Hamiltonian (H er ). In an
More informationMetal Vapour Lasers Use vapoured metal as a gain medium Developed by W. Silfvast (1966) Two types: Ionized Metal vapour (He-Cd) Neutral Metal vapour
Metal Vapour Lasers Use vapoured metal as a gain medium Developed by W. Silfvast (1966) Two types: Ionized Metal vapour (He-Cd) Neutral Metal vapour (Cu) All operate by vaporizing metal in container Helium
More informationLaserphysik. Prof. Yong Lei & Dr. Yang Xu. Fachgebiet Angewandte Nanophysik, Institut für Physik
Laserphysik Prof. Yong Lei & Dr. Yang Xu Fachgebiet Angewandte Nanophysik, Institut für Physik Contact: yong.lei@tu-ilmenau.de; yang.xu@tu-ilmenau.de Office: Heisenbergbau V 202, Unterpörlitzer Straße
More informationPrinciples of Lasers. Cheng Wang. Phone: Office: SEM 318
Principles of Lasers Cheng Wang Phone: 20685263 Office: SEM 318 wangcheng1@shanghaitech.edu.cn The course 2 4 credits, 64 credit hours, 16 weeks, 32 lectures 70% exame, 30% project including lab Reference:
More informationPhoto Diode Interaction of Light & Atomic Systems Assume Only two possible states of energy: W u and W l Energy levels are infinitesimally sharp Optical transitions occur between u and l Monochromatic
More informationCME 300 Properties of Materials. ANSWERS: Homework 9 November 26, As atoms approach each other in the solid state the quantized energy states:
CME 300 Properties of Materials ANSWERS: Homework 9 November 26, 2011 As atoms approach each other in the solid state the quantized energy states: are split. This splitting is associated with the wave
More informationDistributed feedback semiconductor lasers
Distributed feedback semiconductor lasers John Carroll, James Whiteaway & Dick Plumb The Institution of Electrical Engineers SPIE Optical Engineering Press 1 Preface Acknowledgments Principal abbreviations
More informationNoise in voltage-biased scaled semiconductor laser diodes
Noise in voltage-biased scaled semiconductor laser diodes S. M. K. Thiyagarajan and A. F. J. Levi Department of Electrical Engineering University of Southern California Los Angeles, California 90089-1111
More informationSchool of Electrical and Computer Engineering, Cornell University. ECE 5330: Semiconductor Optoelectronics. Fall 2014
School of Electrical and Computer Engineering, Cornell University ECE 5330: Semiconductor Optoelectronics Fall 014 Homework 7 Due on Nov. 06, 014 Suggested Readings: i) Study lecture notes. ii) Study Coldren
More informationLasers & Holography. Ulrich Heintz Brown University. 4/5/2016 Ulrich Heintz - PHYS 1560 Lecture 10 1
Lasers & Holography Ulrich Heintz Brown University 4/5/2016 Ulrich Heintz - PHYS 1560 Lecture 10 1 Lecture schedule Date Topic Thu, Jan 28 Introductory meeting Tue, Feb 2 Safety training Thu, Feb 4 Lab
More informationSemiconductor Physics. Lecture 3
Semiconductor Physics Lecture 3 Intrinsic carrier density Intrinsic carrier density Law of mass action Valid also if we add an impurity which either donates extra electrons or holes the number of carriers
More informationLaser Physics OXFORD UNIVERSITY PRESS SIMON HOOKER COLIN WEBB. and. Department of Physics, University of Oxford
Laser Physics SIMON HOOKER and COLIN WEBB Department of Physics, University of Oxford OXFORD UNIVERSITY PRESS Contents 1 Introduction 1.1 The laser 1.2 Electromagnetic radiation in a closed cavity 1.2.1
More informationUnderstanding Semiconductor Lasers
27 April 2010 age 1 of 8 Experiment II Understanding Semiconductor Lasers The purpose of this experiment is to explore the basic characteristics of semiconductor lasers. We will measure and calculate the
More informationChemistry Instrumental Analysis Lecture 8. Chem 4631
Chemistry 4631 Instrumental Analysis Lecture 8 UV to IR Components of Optical Basic components of spectroscopic instruments: stable source of radiant energy transparent container to hold sample device
More informationSemiconductor Optoelectronics Prof. M. R. Shenoy Department of physics Indian Institute of Technology, Delhi
Semiconductor Optoelectronics Prof. M. R. Shenoy Department of physics Indian Institute of Technology, Delhi Lecture - 18 Optical Joint Density of States So, today we will discuss the concept of optical
More informationFIBER OPTICS. Prof. R.K. Shevgaonkar. Department of Electrical Engineering. Indian Institute of Technology, Bombay. Lecture: 14.
FIBER OPTICS Prof. R.K. Shevgaonkar Department of Electrical Engineering Indian Institute of Technology, Bombay Lecture: 14 Optical Sources Fiber Optics, Prof. R.K. Shevgaonkar, Dept. of Electrical Engineering,
More informationLecture 21: Lasers, Schrödinger s Cat, Atoms, Molecules, Solids, etc. Review and Examples. Lecture 21, p 1
Lecture 21: Lasers, Schrödinger s Cat, Atoms, Molecules, Solids, etc. Review and Examples Lecture 21, p 1 Act 1 The Pauli exclusion principle applies to all fermions in all situations (not just to electrons
More informationAddition of Opacities and Absorption
Addition of Opacities and Absorption If the only way photons could interact was via simple scattering, there would be no blackbodies. We ll go into that in much more detail in the next lecture, but the
More informationThe Electromagnetic Properties of Materials
The Electromagnetic Properties of Materials Electrical conduction Metals Semiconductors Insulators (dielectrics) Superconductors Magnetic materials Ferromagnetic materials Others Photonic Materials (optical)
More informationNanomaterials for Photovoltaics (v11) 14. Intermediate-Band Solar Cells
1 14. Intermediate-Band Solar Cells Intermediate (impurity) band solar cells (IBSCs) (I) Concept first proposed by A. Luque and A. Martí in 1997. Establish an additional electronic band within the band
More informationICPY471. November 20, 2017 Udom Robkob, Physics-MUSC
ICPY471 19 Laser Physics and Systems November 20, 2017 Udom Robkob, Physics-MUSC Topics Laser light Stimulated emission Population inversion Laser gain Laser threshold Laser systems Laser Light LASER=
More informationThe effective factors on threshold conditions in laser diode Passive Q-Switching
J. Basic. Appl. Sci. Res., (4)4079-4084, 0 0, TextRoad Publication ISSN 090-4304 Journal of Basic and Applied Scientific Research www.textroad.com The effective factors on threshold conditions in laser
More informationISSN Review. Progress to a Gallium-Arsenide Deep-Center Laser
Materials 2009, 2, 1599-1635; doi:10.3390/ma2041599 OPEN ACCESS materials ISSN 1996-1944 www.mdpi.com/journal/materials Review Progress to a Gallium-Arsenide Deep-Center Laser Janet L. Pan Yale University,
More informationMODERN OPTICS. P47 Optics: Unit 9
MODERN OPTICS P47 Optics: Unit 9 Course Outline Unit 1: Electromagnetic Waves Unit 2: Interaction with Matter Unit 3: Geometric Optics Unit 4: Superposition of Waves Unit 5: Polarization Unit 6: Interference
More informationAtoms, Molecules and Solids. From Last Time Superposition of quantum states Philosophy of quantum mechanics Interpretation of the wave function:
Essay outline and Ref to main article due next Wed. HW 9: M Chap 5: Exercise 4 M Chap 7: Question A M Chap 8: Question A From Last Time Superposition of quantum states Philosophy of quantum mechanics Interpretation
More informationHomework 1. Property LASER Incandescent Bulb
Homework 1 Solution: a) LASER light is spectrally pure, single wavelength, and they are coherent, i.e. all the photons are in phase. As a result, the beam of a laser light tends to stay as beam, and not
More informationPhys 2310 Fri. Dec. 12, 2014 Today s Topics. Begin Chapter 13: Lasers Reading for Next Time
Phys 2310 Fri. Dec. 12, 2014 Today s Topics Begin Chapter 13: Lasers Reading for Next Time 1 Reading this Week By Fri.: Ch. 13 (13.1, 13.3) Lasers, Holography 2 Homework this Week No Homework this chapter.
More informationQuantum Dot Lasers. Jose Mayen ECE 355
Quantum Dot Lasers Jose Mayen ECE 355 Overview of Presentation Quantum Dots Operation Principles Fabrication of Q-dot lasers Advantages over other lasers Characteristics of Q-dot laser Types of Q-dot lasers
More informationLight Emission. Today s Topics. Excitation/De-Excitation 10/26/2008. Excitation Emission Spectra Incandescence
Light Emission Excitation Emission Spectra Incandescence Absorption Spectra Today s Topics Excitation/De-Excitation Electron raised to higher energy level Electron emits photon when it drops back down
More informationLasers. Optical Fibres
Lasers & Optical Fibres P a g e 2 Contents LASER 1) Coherence 3 2) Interaction of radiation with matter 4 3) Laser fundamentals 5 4) Laser system 5 5) Ruby Laser 6 6) He-Ne Gas Laser 7 7) Semiconductor
More informationTHE DEVELOPMENT OF SIMULATION MODEL OF CARRIER INJECTION IN QUANTUM DOT LASER SYSTEM
THE DEVELOPMENT OF SIMULATION MODEL OF CARRIER INJECTION IN QUANTUM DOT LASER SYSTEM Norbaizura Nordin 1 and Shahidan Radiman 2 1 Centre for Diploma Studies Universiti Tun Hussein Onn Malaysia 1,2 School
More informationDept. of Physics, MIT Manipal 1
Chapter 1: Optics 1. In the phenomenon of interference, there is A Annihilation of light energy B Addition of energy C Redistribution energy D Creation of energy 2. Interference fringes are obtained using
More informationLASERS AGAIN? Phys 1020, Day 17: Questions? LASERS: Next Up: Cameras and optics Eyes to web: Final Project Info
LASERS AGAIN? Phys 1020, Day 17: Questions? LASERS: 14.3 Next Up: Cameras and optics Eyes to web: Final Project Info 1 Group Exercise Your pennies will simulate a two state atom; tails = ground state,
More informationSemiconductor Optoelectronics Prof. M. R. Shenoy Department of Physics Indian Institute of Technology, Delhi
Semiconductor Optoelectronics Prof. M. R. Shenoy Department of Physics Indian Institute of Technology, Delhi Lecture - 20 Amplification by Stimulated Emission (Refer Slide Time: 00:37) So, we start today
More informationExcess carriers: extra carriers of values that exist at thermal equilibrium
Ch. 4: Excess carriers In Semiconductors Excess carriers: extra carriers of values that exist at thermal equilibrium Excess carriers can be created by many methods. In this chapter the optical absorption
More informationOPTICAL GAIN AND LASERS
OPTICAL GAIN AND LASERS 01-02-1 BY DAVID ROCKWELL DIRECTOR, RESEARCH & DEVELOPMENT fsona COMMUNICATIONS MARCH 6, 2001 OUTLINE 01-02-2 I. DEFINITIONS, BASIC CONCEPTS II. III. IV. OPTICAL GAIN AND ABSORPTION
More information