lecture 1

Slide1: 

Physics of Optoelectronics Alexey Belyanin Room 509 ENPH Office: 845-7785 Cell: 324-3071 Email: belyanin@tamu.edu Office hours: any time when I am in the office

Textbook:: 

Textbook: E. Rosencher, B. Vinter, Optoelectronics, 2002

Policy: 

Policy Attendance Questions, discussion are encouraged Several homework assignments Collaboration is encouraged Short presentations in the end of the semester

Optoelectronics:: 

Optoelectronics: Studies electronic devices that interact with light Interact = emit, absorb (detect), modulate, switch Light = any EM radiation Electronic = made of semiconductors

Slide5: 

Basic principles and device physics Examples of state of the art devices Challenges and outlook for the future Plan of study for each kind of devices: Main devices: semiconductor lasers and detectors Systems, E/O interface, integrated photonics Always with applications in mind, but …

Physics perspective on technology is better than EE perspective: 

Physics perspective on technology is better than EE perspective Laser Transistor Computer World Wide Web … Are all invented by physicists

History of the WWW: 

History of the WWW

History of the WWW: 

History of the WWW First proposal: Tim Berners-Lee (CERN) in 1989 1991: First WWW system released by CERN to physics community; first Web server in the US (SLAC) 1993: University of Illinois releases user-friendly Mozaic server Currently: WWW is one of the most popular Internet applications; 60 million users in the US alone

Computer: 

Computer First, there were mechanical calculators …

Slide10: 

Antikythera Mechanism decoded?!

Slide11: 

Found in 1901 near the Antikythera island in a Roman shipwreck dated 80 BC Remained a puzzle for over 100 years Recently deciphered using X-ray tomography, optical imaging, texture mapping Nature, 30 November 2006 (page 587)

Slide12: 

A sophisticated mechanical calculator

Slide13: 

Predicts: Lunar and solar cycles, taking into account ellipticity of the moon’s orbit Lunar and solar eclipses Accurate positions of the sun, moon, and planets Luni-solar calendar Next time when much simpler mechanisms of this kind appeared was in Islamic countries in 1300 AD (Al Biruni) Later they were imported to Europe and became clock mechanisms

Invention of Computer: 

Invention of Computer The first digital electronic computer was invented by Theoretical Physics Prof. John Vincent Atanasoff in 1937. It was built by Atanasoff and his graduate student Clifford Berry at Iowa State College in 1939 ($650 research grant). Basement of the Physics Dept. building where the Atanasoff-Berry Computer (ABC) was built.

ABC: 

ABC Used base-two numbers (the binary system) - all other experimental systems at the time used base-ten Used electricity and electronics as it's principal media Used condensers for memory and used a regenerative process to avoid lapses that could occur from leakage of power Computed by direct logical action rather than by the enumeration methods used in analog calculators Implemented principles of modern computers Only material base has been changed.

Slide16: 

ABC Replica The drum – the only surviving fragment of ABC. It holds 30 numbers of 50 bits each. They are operated on in parallel. It is the first use of the idea we now call "DRAM" -- use of capacitors to store 0s and 1s, refreshing their state periodically. Card punch and reader Berry with the ABC

From ABC to ENIAC: 

From ABC to ENIAC 1940s: J. Mauchly and J. Eckert build ENIAC (Electronic Numerical Integrator And Computer). All basic concepts and principles of ENIAC are “borrowed” from Atanasoff’s papers. 1972: U.S. Court voids the Honeywell’s patent on the computing principles and ENIAC, saying that it had been “derived” from Atanasoff’s invention. 1990: Atanasoff receives the U.S. National Medal of Technology. He dies in 1995 at the age of 91.

From ENIAC to …: 

From ENIAC to … ENIAC (1946) weighed 30 tons, occupied 1800 square feet and had 19,000 vacuum tubes. It could make 5000 additions per second Computers in the future may weigh no more than 1.5 tons. (Popular Mechanics, 1949) 1940's - IBM Chairman Thomas Watson predicts that "there is a world market for maybe five computers". 1950's - There are 10 computers in the U.S. in 1951. The first commercial magnetic hard-disk drive and the first microchip are introduced. Transistors are first used in radios. 1960's-70's - K. Olson, president, chairman and founder of DEC, maintains that "there is no reason why anyone would want a computer in their home." The first microprocessor, 'floppy' disks, and personal computers are all introduced. Integrated circuits are used in watches.

Slide19: 

Before diodes and transistors: vacuum tubes 1954-1963: SAGE Air Defense Project 23 32-bit computers Each contains 55,000 vacuum tubes, weighs 250 tons, and consumes 3 Megawatt Tracks 300 flights Total cost: $60 billion (double the price of Manhattan Project!) Performance equivalent to $8 calculator built on transistors!

Slide20: 

Intel Pentium 4 Processor Extreme Edition (Nov. 3, 2003) Clock speed: 3.20 GHz Mfg. Process: 0.13-micron Number of transistors: 178 million 2 MB L3 cache; 512 KB L2 cache Bus speed: 800 MHz The electronics and semiconductor industries account for around 6.5% of the gross domestic product, representing over $400 billion and 2.6 million jobs. The telecommunications industry earns $1.5 trillion each year and employs 360,000 Americans.

Slide21: 

Moore’s Law (1965): every 2 years the number of transistors on a chip is doubled Smaller, Denser, Cheaper

Slide22: 

Limit on the transistor size Limit on the manufacturing technology

Pushing Fundamental Limits:Challenges and Bottlenecks: 

Pushing Fundamental Limits: Challenges and Bottlenecks Semiconductors: how small the transistor can be? Memory and data storage: limits on writing density? Communications: limits on data rate?

Slide24: 

Telecommunications

Slide25: 

Modulation speed of semiconductor lasers is limited to several Gbits/sec Electric-to-optical conversion is slow and expensive

LASER = Light Amplification by Stimulated Emission of Radiation: 

LASER = Light Amplification by Stimulated Emission of Radiation Laser is a device which transforms energy from other forms into (coherent and highly directional) electromagnetic radiation. 1917 – A. Einstein postulates photons and stimulated emission 1954 – First microwave laser (MASER), Townes, Shawlow, Prokhorov 1960 – First optical laser (Maiman) 1962 – First semiconductor laser: Basov, Hall, … 1964 – Nobel Prize in Physics: Townes, Prokhorov, Basov 2000 - Nobel Prize in Physics: Alferov, Kroemer, Kilby Chemical energy Electron beam Electric current Electromagnetic radiation …

Laser radiation: 

Laser radiation Monochromaticity Directionality Coherence

Monochromaticity: 

Monochromaticity

Directionality: 

Directionality Radiation comes out of the laser in a certain direction, and spreads at a defined divergence angle () This angular spreading of a laser beam is very small compared to other sources of electromagnetic radiation, and described by a small divergence angle (of the order of milli-radians) Lamp: W = 100 W, at R = 2 m He-Ne Laser: W = 1 mW, r = 2 mm, R = r + R /2 = 2.1 mm, I = 8 mW/cm2

Coherence: 

Coherence Laser radiation is composed of waves at the same wavelength, which start at the same time and keep their relative phase as they advance.

Interference: 

Interference Young Interference Experiment

Michelson Interferometer: 

Michelson Interferometer Nobel Prize in Physics 1907

Slide38: 

For a completely coherent wave, defining its phase along particular surface at specific time, automatically determine its phase at all points in space at all time. Temporal Coherence is related to monochromaticity. Spatial Coherence is related to directionality and uniphase wavefronts. Coherence time tc ~ 1/, where  is linewidth of laser radiation Coherence Length (Lc) is the maximum path difference which still shows interference: Lc = ctc = c/ Typical laser linewidths: from MHz to many GHz Record values ~ Hz

Laser System: 

Laser System Active (gain) medium that can amplify light that passes through it Energy pump source to create a population inversion in the gain medium Two mirrors that form a resonator cavity

Amplifier vs. Generator: 

Amplifier vs. Generator No (or negative) feedback: Positive feedback: