Re: How big is the field of fibre optics? Could light compete with electicity .

Greetings: 

The 20th century has been called the Electronics Century and many scientists 
predict that the 21st century will be the Photonics Century. This means that 
photons of light will be used in place of electrons of electricity to 
create, sense, store, transmit and display information. The key to the 
electronics revolution was the development of the electronic amplifier 
during the first 10 years of this century (1900 to 1910). The key to the 
photonics revolution was the demonstration of the first light amplifier, the 
Laser, in 1960. 

Photonics (also called optoelectronics) technology, which includes lasers, 
fiber optic transmission lines, detectors, storage and displays, is roughly 
paralleling the development of electronics technology only it’s happening 
about 50 years later. Today most, but not all, of the functions performed by 
electronics circuits can now be performed by photonic circuits (e.g. 
Photonic computers are not yet practical). Photonic circuits have the 
potential of moving and controlling huge amounts of information using 
smaller, more efficient and lower cost devices. Today one channel of laser 
light in a fiber optic transmission line can carry all of the information in 
the radio spectrum at the same time including all AM radio stations, all FM 
radio stations, all TV channels, cell phones, air traffic control, radar, 
satellite communications etc. We are now beginning to put dozens of laser 
carriers signals of different wavelengths (colors) through a single fiber, 
increasing the information capacity dozens of times. 

Fundamentally there are two basic devices that enabled the electronic 
revolution and are now enabling the photonic revolution, the AMPLIFIER and 
the OSCILLATOR. LASERS were first developed by Dr. T. H. Maiman in 
California in 1960 while he was working on new types of ELECTRONIC 
AMPLIFIERS called MASERS - (M)icrowave (A)mplification by (S)timulated 
(E)mission of (R)adiation). The first two letters of LASER stand for light 
amplification and the remaining letters tell us how it works. - (L)ight 
(A)mplification by (S)timulated (E)mission of (R)adiation. I have 
capitalized a number of technical names in the text for those readers that 
would like to study more about lasers. 

ELECTRONIC AMPLIFIERS AND OSCILLATORS 

Science in the 19th century considered the atom to have a nucleus at its 
core with electrons orbiting around the nucleus in a manner similar to 
planets orbiting the sun. In some elements, called CONDUCTORS, the electrons 
farthest from the nucleus are easy to pull off the atom (IONS) while 
electrons close to the nucleus are more tightly tied to the atom. 

The science of electricity and magnetism is based on ELECTRICAL PRESSURE 
(units called VOLTAGE or VOLTS) produced by generators
and/or batteries to force the outer electrons in CONDUCTORS to hop from atom 
to atom in the wires forming ELECTRICAL CIRCUITS. In the
last century (19th) millions of electrons flowing through circuits were used 
to produce a controlled ELECTRICAL CURRENT (units called
Amperes or AMPS) to flow in light bulbs, motors, telegraphs, telephones and 
appliances. The wires, light bulb filaments etc. try to resist the flow of 
electrons causing the wires and circuits to heat up. This attempt to resist 
electron flow is ELECTRICAL RESISTANCE (units called OHMS). 

In this century (20th) radios, televisions, telephones, and computers were 
developed to enable the field of ELECTRONICS where electrons are used for 
transmitting, sensing, storing, displaying and sorting information. The key 
invention that made this all possible was the ELECTRONIC AMPLIFIER that was 
first invented by Dr. Lee De Forrest in California during the first 10 years 
of this century (1900 to 1910). The electronic voice, picture and data 
signals we all use today grow very weak, very quickly as they travel through 
the RESISTANCE in wires and cables. Before the electronic amplifier people 
had to shout into their telephones and the signals could be heard only a few 
hundred km (miles) away even with the best wire connections. Today, with 
electronic amplifiers to boost the signals, our telephone calls can go 
around the world through undersea cables and up through satellites in space
20,0000 miles above the earth and yet the calls sound like they come from 
your own hometown. 

Perhaps you have seen old motion pictures on TV from the 1930s and you have 
seen people shouting HELLO, HELLO CAN YOU HEAR ME
into their telephones. This was before ELECTRONIC AMPLIFIERS were routinely 
placed in telephone centers. AMPLIFIERS were first used for long
distance telephone calls in 1926 when the first call was made between the 
east and west coasts of the U.S.A. However, it took until 1956 for the first 
transatlantic telephone cable with amplifiers spaced every few  miles apart 
under the sea to boost the signals as they weakened from resistance in the 
cable. The first transatlantic television signal by cable was made in the 
early 1990s and that used lasers and fiber optic cables!
(Satellites using microwave signals have been used for transoceanic 
telephone and TV since the 1960s). 

We need signals at a level of about one volt to hear them from a loud 
speaker, telephone or to see pictures on a TV (a flashlight battery is about 
1 and 1/2 volts). The electromagnetic waves that reach our houses from radio 
stations and TV stations generate about one millionth of a volt in our home 
antennas! Therefore we need to boost these signals with amplifiers in our 
home TV set by about a million times before we can see and hear
them! 

Each of Dr. De Forrest's electronic amplifier tubes , a glass VACUUM TUBE 
called a TRIODE, was able to boost the strength of electronic signals by 
about 100 times. Two tubes in a row could boost the signals 100 times 100 = 
ten thousand times. Radios were developed in the 1920s with 3, 4 or 5 
amplifiers in a row so that radio signals could be boosted one million 
times. In the 1950s and 1960s smaller more efficient transistor amplifiers 
were invented at the Bell Telephone Labs in New Jersey to replace the larger 
tube amplifiers and we now have portable transistorized
TVs, telephones and computers. Color television sets require amplifiers for 
the sound circuits and for the red, green and blue picture signals and these 
sets have dozens of transistor ELECTRONIC AMPLIFIERS and OSCILLATORS in 
them. 

Besides the electronic AMPLIFIER there is a second important circuit that 
makes modern electronics possible, the OSCILLATOR. Perhaps you have been at 
meetings where the sound system squeals when the person on stage turns the 
microphone on. We call this annoying condition FEEDBACK. If you place a 
microphone connected to the input of a public address system amplifier near 
to the output loud speaker you hear a very loud squeal that hurts your ears. 
It is caused by weak signals from the microphone being amplified and then 
passing from the loud speaker back through the microphone and amplifier 
again and again and being amplified many times over. The closer the 
microphone is to the speaker (the shorter the feedback path) the higher the 
note will be . For longer feedback paths the note will be lower. 

In the 1930s scientists purposely used wires of fixed length to control 
samples of the amplifier output power and to FEEDBACK these samples into the 
amplifier input circuits. An amplifier with controlled feedback will 
OSCILLATE and produce an amplified pure tone or a single musical note. 
Oscillators with very, very small feedback paths are also used to generate 
radio and television transmitter carrier waves that have the picture and 
sound information modulated onto them. The musical A note used to tune up 
orchestras is 440 cycles per second, AM radio uses oscillators near 1 
million cycles per second, FM radio oscillators work near 100 million cycles 
per second, and television oscillators reach near one billion cycles per 
second at the  UHF (ultra high frequency) channels. Thus each radio station 
or TV channel is generated by an electronic oscillator set to a precise 
number of cycles per second determined by a special feedback circuit in your 
set. 

OPTICAL AMPLIFIERS AND OSCILLATORS 

During the first 30 years of the 20th Century QUANTUM MECHANICS was 
developed and theories were developed to explain the atomic
behavior observed in nature much more accurately than could be explained by 
the simple orbiting electron model. Also, it was theorized that light 
consisted of PHOTONS, discrete packets of energy, that were quantized by 
frequency (color). This means that the light spectrum observed in a rainbow 
or from the sun passing through a prism is not continuous in color change 
but that each PHOTON has an exact frequency of oscillation
(color) and the color changes are separated by one cycle per second. Also; 
red light PHOTONS have less energy in each photon with increasing photon 
energy in orange, yellow, green, blue, and violet PHOTONS. PHOTONS of blue 
light have about 2 times more energy than photons of red light. This also 
means that their are thousands of millions  (billions) of exact colors 
(notes of light) in the light spectrum just as a piano has about 88 notes on 
the keyboard. However, until the demonstration of the first laser in 1960 
these pure frequencies (notes or tones) of light could not be directly 
observed. 

Scientists also theorized (also proven by experiment) that each electron 
surrounding an atom has an exact energy level (orbit) and that no two 
electrons in an atom can have the same exact energy. This quantizing of 
electron energy was pictured as atoms with electrons in hundreds of possible 
orbits with each orbit having an exact energy multiple of 1, 2, 3, 4 - - - 
times etc. from the lowest to the highest energy orbits. 

Scientists also theorized (also proven by experiment) that if an electron 
jumps from a higher energy orbit to a lower energy orbit the atom gives off 
a PHOTON of light energy at a color that exactly equals the energy 
difference of the orbit energy change. Also, when an electron changes from a 
lower energy orbit to a higher energy orbit the atom absorbs light with 
photons that have the exact energy that matches the orbit energy change.
Thus orbital energy changes of electrons could be used to control a light 
amplifier or oscillator. 

In the 1950s during the cold war scientists were looking for new types of 
QUANTUM MECHANICAL AMPLIFIERS for microwave radar and communications 
applications that would be much more sensitive than vacuum tube and 
transistor amplifiers then in use. In 1954 Professor Charles Townes and his 
students at Columbia University in New York City developed the world's first 
quantum mechanical amplifier and named it the MASER for
(M)icrowave (A)mplification by (S)timulated (E)mission of (R)adiation. 
MASERS are the most sensitive amplifiers ever made by man and today RUBY 
MASERS are installed in all of the giant antennas used for radio astronomy 
and for deep space communications. The reason we can get pictures back
from space craft visiting the outer planets of the solar system many 
millions of miles away from earth is because of the giant antennas that 
collect the extremely small energy signals and the RUBY MASER amplifiers at 
the focal point of these antennas that are millions of times more sensitive 
than the amplifiers in our home electronic equipment. (MASERS and LASERS 
work in a similar yet basically different manner which I will not discuss
here) 

Once the laser light amplifier was developed it was immediately turned into 
an oscillator by using FEEDBACK. We can't use wires for light feedback but 
we can use mirrors.Dr. Maiman coated each end of his ruby rod in the first 
laser with mirrors so that the photons of light from STIMULATED EMISSION 
reflect thousands of times back and forth between the mirrors stimulating 
more and more electrons to emit more light with each pass through the ruby 
crystal. This is a light oscillator which is the most common
form LASERS take. Now to get some useful light out of the device, Dr. Maiman 
put a small hole in the middle of one end mirror so that about one percent 
of the light in the ruby crystal could escape and form the first laser beam, 
while 99% of the light went on stimulating emission in the ruby
crystal until all the electrons fell to the lower energy levels. The first 
RUBY LASER produced a pulse of laser light for only a microsecond, one pulse 
of light for each flash of a flash lamp surrounding the ruby crystal. Later 
models used a continuous flash lamp and a continuous laser beam was 
obtained. Later many improvements were made in laser designs and the fields 
of LASER PHYSICS and LASER ENGINEERING were born. 

The rest is history and since 1960 hundreds of laser types have been 
invented. They operate at thousands of visible colors and in the infrared 
and ultraviolet spectrum. Each color of laser is set by engineering the 
electron orbits in the laser material. Laser materials used today include 
gasses, liquids and solid crystals. Today we also have semiconductor chip 
lasers the size of a grain of salt which sell for a few dollars and are used 
in compact disk (CD) record players, computer ROMS, DVDs and as printers and 
pointers. Electronics stores now sell red laser diode pointer for about $10 
(US). Today lasers are used in hundreds of applications ranging from 
supermarket checkout stands to eye surgery. You can see the first laser and 
many new laser related activities and related links at the Web Site for the 
Hughes Research Laboratories where the first laser was demonstrated in 1960: 
 http://www.hrl.com/ 

FIBER OPTIC AMPLIFIERS
Fiber optic transmission lines are far more efficient than electrical cables 
and can carry many more signals much longer distances than electronic cables 
before the signals become weak and must be amplified. In long distance 
telephone circuits, such as under sea cables, these repeaters had to be 
placed in the line about every 3 km (2 miles). The hundreds of transocean 
fiber optic cables that have been  placed in the ocean since the 1980s have 
had electronic repeaters spaced about 30 km (20 miles) which was a a ten 
times improvement over electrical cables. 

In the 1990s a new fiber containing the element erbium (Er) was developed 
that could also be made into a laser amplifier. By splicing 10 meters (30 
ft) of these Er doped fiber amplifiers into a fiber optic transmission line, 
the light signal is amplified 1000 times (30dB) and no electronic amplifiers 
are required. The first of a new class of under sea cables using fiber 
amplifiers are now being developed and deployed. They can transmit huge 
amounts of information across oceans without the need for any electronic 
amplifiers! These wires with gain instead of loss will also revolutionize 
all sorts of communications lines and circuits.

Best regards for Y2K+, Your Mad Scientist
Adrian Popa