Description
Optical
filter
Introduction
Optical fiber is an instrument that
is used for wavelength selection, which can
selectdesired
wavelengths to pass and reject
the others. It is Widely used inDWDM systems dynamic wavelength selection, DWDM
signal separation, optical performance monitoring, field tunable
optical noise filtering and optical amplifier noise suppression,
etc.
Optical multiplexers (couplers) makes different
wavelength coupling into an optical fiber and different wavelength
carries different information. At the receiving end, if you want to
separate desired wavelengths from optical fiber, it is necessary to
use optical filter
Characteristics
many wavelengths selection,
channel spacing can be very small, low manufacturing cost, small
polarization dependent loss, small design, fast installation,
stable and reliable performance, different connector can be
provided according to customer demand
Application
FTTX optical fiber communication
systems, WDM system, LAN, CATV, fiber optic sensing, fiber
amplifiers, fiber laser, measuring instruments, medical
equipment.
Principle
Grating
spectrometer principle
The above drawing is a schematic
diagram of grating separating the mixed lightwave.Mixed
wavelengths（λ1ã€λ2ã€λ3）from
optical fiber , After the collimating lens (L1) post-directed to
the grating，the
optical signals of different wavelengths due to the different
diffraction angle, is focused to different position through the
lens (L2),then the optical signal is coupled into different optical
fiber for output. This is the principle of the grating
spectrometer.
Prism spectroscopic
principle
Prism spectroscopic principle as
shown in drawings,Its working
principle is:Contains more
than one optical signal wavelength of light,As a result of Lens
collimator,separated the light
through the prism ,After the
separation of light through another lens is focused and coupled
into the corresponding optical fiber in the
spread.As well known, the
propagation velocity of the different wavelengths in the same kind
of material is not the same,That refractive index n (n = c / V) with
wavelength dependent,If choose
dn / dλ material for prism, you can get large angular dispersion of
skills and high color resolution power.
In addition,When the width of the prism surface is
appropriately increased, and as far as possible to reduce the
diameter of the collimating lens,You can get the best performance
of the spectral effects,The
lens, in the above system can be used to replace the self-focusing
lens, its effect is completely the same.
Interference film filter
principle
The interference film structure as shown in the
drawings.The superposition of
alternating dielectric film by both refractive index (n) of varying
sizes.Its thickness is 1/4
wavelength,By different
choices of the dielectric film constituting longwave pass,
shortwave pass, and band pass filter.A high refractive index layer of the light
reflected from its phase does not shift,The reflected light of the low refractive index
layer whose phase is shifted by **0 degrees,Reflected several times through the interface of
each film and the linear superposition of the transmitted light,
when the optical wavelength of the optical path difference is equal
to, or the same phase, multiple transmitted light will interfere
with phase strengthened, to form a strong transmitted
lightwaveinverting lightwave offset each other. Can be obtained a
good filtering performance filters by appropriate design of the
dielectric multilayer film systems.
Categories
Base on the raster principle of
filter: grating filter, arrayed waveguide grating the filter (AWG),
fiber grating filter, sound and light tunable filter.
According to different principle of optical filter, we
can do it according to customers’ different demand
