Definitions
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Bandwidth |
A measure of the frequency spread of a signal or system—that is, its information-carrying capacity. |
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Chirping |
The time dependence of the instantaneous frequency of a signal. |
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Commutator/decommutator |
A device that assists in the sampling, multiplexing, and demultiplex- |
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ing of time domain signals. |
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Homogeneous broadening |
A physical mechanism that broadens the line width of a laser transition. The amount of broadening is exactly the same for all excited states. |
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Kerr effect |
The dependence of a material’s index of refraction on the square of an applied electric field. |
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Mode partion noise |
Noise associated with mode competition in a multimode laser. |
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Multiplexing/demultiplexing |
The process of combining and separating several independent signals that share a common communication channel. |
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Passband |
The range of frequencies allowed to pass in a linear system. |
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Photon lifetime |
The time associated with the decay in light intensity within an optical resonator. |
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Picosecond |
One trillionth of a second. |
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p-n junction |
The region that joins two materials of opposite doping. This occurs |
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when n-type and p-type materials are joined to form a continuous crystal. |
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Pockel’s effect |
The dependence of a material’s index of refraction on an applied electric field. |
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Quantum confined Stark effect (QCSE) |
Optical absorption induced by an applied electric field across a semiconductor quantum well. |
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Quantum well |
A thin semiconductor layer sandwiched between material with a larger band gap. The relevant dimension of the layer is on the order of 10 nm. |
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Sampling |
The process of acquiring discrete values of a continuous signal. |
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Spatial hole burning |
The resultant nonuniform spatial distribution of optical gain in a material owing to standing waves in an optical resonator. |
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Spontaneous emission |
An energy decay mechanism to reduce the energy of excited states by the emission of light. |
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Stimulated emission |
An energy decay mechanism that is induced by the presence of light in matter to reduce the energy of excited states by the emission of light. |
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Terabit |
1 trillion bits. |
Abbreviations
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ADC |
analog-to-digital converter |
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APD |
avalanche photodetector |
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CEPT |
European Conference of Postal and Telecommunications Adminis trations |
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CMI |
code mark inversion |
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DBR |
distributed Bragg reflector |
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DFB |
distributed feedback |
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DS |
digital signal |
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EDFA |
erbium-doped fiber amplifier |
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FDM |
frequency-division multiplexing |
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FP |
Fabry-Perot |
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LED |
light-emitting diode |
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NRZ |
non-return-to-zero |
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OC-N |
optical carrier (Nth level) |
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OOK |
on-off keying |
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PAM |
pulse amplitude modulation |
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PCM |
pulse code modulation |
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PLL |
phase-locked loop |
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PLM |
pulse length modulation |
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PPM |
pulse position modulation |
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RZ |
return-to-zero |
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SDH |
synchronous digital hierarchy |
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SLALOM |
semiconductor laser amplifier loop optical mirror |
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SONET |
synchronous optical network |
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SPE |
synchronous payload envelope |
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STS |
synchronous transmission signal |
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TDM |
time-division multiplexing |
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TDMA |
time-division multiple access |
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TOAD |
terahertz optical asymmetric demultiplexer |
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UNI |
unbalanced nonlinear interferometer |
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WDM |
wavelength-division multiplexing |
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VCO |
voltage-controlled oscillator |
Symbols
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number of bits respresenting N levels in an analog-to-digital converter |
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sampling frequency |
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number of levels in an analog-to-digital converter |
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index of refraction; integer |
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periodic sampling pulse train |
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mirror reflectivities |
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period |
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bandwidth of a signal in hertz |
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sampled version of a continuous function of time |
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continuous analog signal |
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frequency spectrum of the signal x(t) |
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delta function |
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grating period |
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wavelength |
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photon decay time or photon lifetime |
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round-trip propagation time of an optical cavity |
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phase shift |
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angular frequency (radians per second) |
