636
Appendix D: List of Important Roman Symbols
(continued)
Symbol
Definition
G
Amplifier gain
g B
Brillouin gain coefficient
h
Planck’s constant = 6.6256 × 10 −34 J-s = 4.14 eV-s
H
Magnetic field
I
Optical field intensity
i B
Bias current
i D
Photodetector bulk dark current
I DD
Directly detected optical intensity
i M
Multiplied photocurrent
i p
Primary photocurrent
i p (t)
Signal photocurrent
i th
Threshold current
i 2
s
Mean-square signal current
i 2
shot
Mean-square shot-noise current
i 2
dark
Mean-square detector dark noise current
i 2
th
Mean-square thermal noise current
J
Current density
J th
Threshold current density
k
Wave propagation constant (k = 2π/λ)
K
Stress intensity factor
k B
Boltzmann’s constant = 1.38054 × 10 −23 J/K
L
Fiber length
L c
Connection loss
L disp
Dispersion length
L eff
Effective length
L F
Fiber coupling loss
L i
Intrinsic loss
L n
Electron diffusion length
L p
Hole diffusion length
L period
Soliton period
L split
Splitting loss
L tap
Tap loss
m
Modulation index or Modulation depth
m
Order of a grating
M
Avalanche photodiode gain
M
Number of modes
m e
Effective electron mass
(continued)