For example, installing an optical isolator between the semiconductor laser source and an optical transmission system can greatly reduce the reflected light’s adverse effects on the stability of the spectral output power. In the high-speed direct modulation of the direct detection of optical fiber communication systems, the backward propagation light will produce additional noise, which will degraded the system performance, which also requires an optical isolator to eliminate. Installing an optical isolator at both ends of the doped fiber in the optical fiber amplifier can improve the operation stability of the optical fiber amplifier. If without it, the back reflected light will enter into the signal source (laser), which will cause the serious fluctuations of the signal source. In the coherent long-distance optical fiber communication systems, there will install an optical isolator at some distance to reduce the power loss caused by Brillouin scattering. Therefore, the optical isolator is an important role in the optical fiber communication, optical information processing systems, optical fiber sensing and precision of the measuring optical system.
Currently, it is mostly applied in chip integrated all-optical path. Now, the researches are focusing on the issue how to integrate the optical isolator with COMS circuit.
The characteristics of the optical isolator are high isolation, low insertion loss; high reliability, high stability; very low PDL and PDM.
There is a variety of optical isolators, including the-line isolator, free-space optical isolator etc.
Fiberer.com Optical Isolator type common as follow:
1310nm Optical Isolator
1550nm Optical Isolator
830nm / 850nm / 980nm Isolator
1030nm / 1060nm Isolator
850nm /980nm / 1060nm PM Isolator
1310 /1550 /1064nm Free Space Isolator
We provide a variety of optical isolators in order to meet the needs of different application areas. The inner design of 1310/1480/1550nm polarization-independent optical isolator are applied relative processing technology according to the two kinds of orthogonal polarization states of the single-mode fiber, which have ensured the polarization-independent characteristics of the entire device. One-stage devices with low insertion loss, two-stage devices with high optical isolation, they are suitable for different applications and mainly applied in fiber amplifiers, fiber lasers, optical fiber CATV network and satellite communications etc.
Optical isolator is usually classified by wavelengths. Many of them are 800-1300nm. Meanwhile, there are also some special wavelengths.
Connected the output terminal of the LD light source to the power meter by the optical jumper, the output power read on the power meter will be the input power of the optical isolator.
Optical isolator is mainly using the Faraday Effect of the magneto-optical crystal. Faraday Effect, Faraday first observed that non-optically active material in the magnetic field will rotate the polarization direction of light in 1845, is also known as Magnetic Rotation Effect. The rotation angle of the polarization light along direction of the magnetic field is ¦È, which is proportional to the product of magnetic field strength B and material length L. The operating principle of the optical isolator is shown as Picture 1.
For the passive incident signal light, it will become linearly polarized light through the polarizer. The Faraday rotating magnetic media and the external magnetic field together will make the polarization direction of the signal light turn 45 degrees in a clockwise, which will just get the low loss through the analyzer who has 45 degrees with the polarizer. For the reverse incident signal light, the linearly polarized light out from the analyzer will also turn 45 degrees in a clockwise through the media, which will make the direction of the reverse polarization light orthogonal to the direction of the polarizer and completely block the reflected light’s transmission. .
Faraday magnetic media is usually choosing the yttrium iron garnet (YIG) single crystal which is low loss among the wavelength range 1¦Ìm ~ 2¦Ìm. The new pigtail input and output optical isolator has fairly good performance, its minimum insertion loss is approximately 0.5 dB, isolation is up to 35 ~ 60dB, the best is 70dB.