光纤通信RF方面的中英文翻译

RF

和微波光纤设计指引

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Student NO.:

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RF and Microwave Fiber-Optic Design Guide

Agere Systems Inc., through its predecessors, began developing and producing

lasers

and

detectors

for

linear

fiber-optic

links

nearly

two

decades

ago.

Over

time,

these optoelectronic components have been continually refined for integration into a

variety

of

systems

that

require

high

fidelity,

high

frequency,

or

long-distance

transportation

of

analog

and

digital

signals.

As

a

result

of

this

widespread

use

and

development, by the late 1980s, these link products were routinely being treated as

standard RF and microwave components in many different applications.

There

are

several

notable

advantages

of

fiber

optics

that

have

led

to

its

increasing use. The most immediate benefit of fiber optics is its low loss. With less

than 0.4 dB/km of optical attenuation, fiber-optic links send signals tens of kilometers

and still maintain nearly the original quality of the input.

The low fiber loss is also independent of frequency for most practical systems.

With laser and detector speeds up to 18 GHz, links can send high-frequency signals

in

their

original

form

without

the

need

to

downconvert

or

digitize

them

for

the

transmission

portion

of

a

system.

As

a

result,

signal

conversion

equipment

can

be

placed

in

convenient

locations

or

even

eliminated

altogether,

which

often

leads

to

significant cost and maintenance

savings.

Savings

are

also

realized

due

to

the

mechanical

flexibility

and

lightweight

fiber-optic cable, approximately 1/25 the weight of waveguide and 1/10 that of coax.

Many transmission lines can be fed through small conduits, allowing for high signal

rates

without

investing

in

expensive

architectural

supports.

The

placement

of

fiber

cable is further simplified by the natural immunity of optical fiber to electromagnetic

interference

(EMI).

Not

only

can

large

numbers

of

fibers

be

tightly

bundled

with

power

cables,

they

also

provide

a

uniquely

secure

and

electrically

isolated

transmission path.

The

general

advantages

of

fiber-optics

first

led

to

their

widespread

use

in

long-haul

digital

telecommunications.

In

the

most

basic

form

of

fiber- optic

communications, light from a semiconductor laser or LED is switched on and off to

send digitally coded information through a fiber to a photodiode receiver.

By

comparison,

in

linear

fiber- optic

systems

developed

by

Lucent,

the

light

sent through the fiber has an intensity directly related to the input electrical current.

While this places extra requirements on the quality of the lasers and photodiodes, it

has been

essential in many applications to transmit arbitrary RF and microwave signals. As a

result, tens of thousands of Agere Systems’ transmitters are currently in use.

The information offered here examines the basic link components, provides an

overview of design calculations related to gain, bandwidth, noise, and dynamic range

1

and

distortion.

A

section

on

fiber-optic

components

discusses

a

number

of

key

parameters,

among

them

wavelength

and

loss,

dispersion,

reflections,

and

polarization

and

attenuation.

Additional

information

evaluates

optical

isolators,

distributed- feedback lasers and Fabry-

Perot lasers, predistortion, and short- vs. long- wavelength transmission.

One

of

linear

optical

fiber

relation

main

usages

or

receives

between

the

electronic

installation

and

the

remote

localization

antenna

in

the

transmission

transmits RF and the microwave signal

。

Because of the optical fiber chain flexibility

，

possibly can for the simulation or digital signal design some antennas

，

including the

military

and

the

commercial

communications

satellite

，

the

global

localization

satellite

，

the remote sensing with traces the lighthouse

，

or wireless cell network

。

Another kind of type chain is the optical fiber

delay line

，

installs in a package it

including a transmitter

，

a receiver

，

with long textile fiber

。

It may provide the long

delay time, high band width, with low weight.

These high- frequency RF and the microwave product has obtained benefits from

the

use

linear

optical

fiber

equipment

cable

television

raging

tide

middle

earth.

In

here,

the

textile

fiber

expands

the

TV

signal

the

transmitting

range,

improves

their

quality and the system reliability, but when merely only has the electric cable, even

with the system which used compares has saved the expense

In

each

of

these

applications,

as

well

as

many

others,

the

Agere

Systems’

transmitters

and

receivers

comprising

the

links

are

similar

and

can

be

treated

as

standard

microwave

components.

Focusing

on

these

common

elements,

this

design

guide

describes

the

general

technical

considerations

and

equations

necessary

for

engineers

to

choose

the

most

appropriate

Agere

Systems’

components

for

their

systems. These equations also have been incorporated into various programs, which

an Agere Systems’ applications engineer can use to provide an analysis for a specific

link application.

Figure

1

shows

the

three

primary

components

in

a

fiber-optic

link:

an

optical

transmitter, a fiber-optic cable, and

an optical

receiver.

In the transmitter, the input

signal

modulates

the

light

output

from

a

semiconductor

laser

diode,

which

is

then

focussed into a fiber- optic cable. This fiber carries the modulated optical signal to the

receiver, which then reconverts the optical

signal

back to

the original electrical

RF

signal.

2