The optical transceiver module consists of optoelectronics, functional circuits and optical interfaces, etc. The optoelectronics include both transmitting and receiving parts. Also known as optical transceiver module. So much has been said before, to put it plainly, the optical module is an electrical to optical, optical to electrical an electronic product, it can convert the signal into an optical signal, so that the transmission distance becomes more transportable.
According to the working wavelength classification, the unit nanometer (nm), there are currently three main kinds of.
850nm (MM, multi-mode, low cost but short transmission distance, generally only 500M transmission);
1310nm (SM, single mode, large loss during transmission but small dispersion, generally used for transmission within 40KM);
1550nm (SM, single mode, low loss but high dispersion during transmission, generally used for long-distance transmission over 40KM, up to 120KM without relay);
The number of bits of data transmitted per second (bit), in bps.
Currently, there are five common types: 155Mbps, 1.25Gbps, 2.5Gbps, 6Gbps, 10Gbps, etc. The transmission rate is generally backward compatible, so 155M optical module is also called FE (100 Gigabit) optical module, 1.25G optical module is also called GE (Gigabit) optical module, which is currently the most used module in optical transmission equipment. In addition, it has 2Gbps, 4Gbps, 6 Gbps and 8Gbps transmission rate in fiber optic storage system (SAN).
1. Analysis of common causes of optical module damage
Optical port contamination and damage
Due to optical interface contamination and damage caused by optical link loss becomes large, resulting in optical link does not work. The reasons for this are
a, optical module optical port is exposed to the environment, the optical port is contaminated by the entry of dust;
b, the use of fiber optic connector end face has been contaminated, optical module optical port secondary pollution;
c, improper use of the end face of the optical connector with pigtail, end face scratches, etc.;
d, the use of poor quality fiber optic connectors;
e, improper plugging and unplugging, ceramic sleeve rupture, etc.
f, abnormal operation, such as: non-hot-swappable optical module charged operation; do not do electrostatic protection directly touch the optical module electrostatic sensitive pin; transportation and storage process without anti-static packaging;
g, the equipment is not grounded or poor grounding.
2. Precautions for the use of optical modules
Optical module inside the integrated precision optical components and circuit components, in the process of daily use to pay attention to the standard operation, otherwise it is easy to cause damage to the optical module, the following is an introduction to the daily use of optical module precautions.
(1) The correct installation of the module
a. Ensure that the module is properly installed. When installing the optical module to force the module into the bottom, hear the "snap" sound or feel a slight vibration, that the module card lock card in place. When the optical module card lock is not in place, the gold finger and the single board connector micro-contact, the link may be connected, but in the case of vibration, collision, etc., the optical module will occur transient break, or even loose and other failures;
b, optical module internal ceramic parts, take care when picking up the optical module, if inadvertently dropped or knocked, the optical module is not recommended to be used on the shelves to avoid subsequent failure;
c, to the optical module when inserting the fiber optic cable requires gentle action, right into the optical port insertion, excessive force or oblique insertion, there is a risk of damage to the optical module;
d, most optical modules support hot-swapping, but not recommended for regular hot-swapping, easy to cause electrical damage;
e, confirm the unplugging optical module action specification: take the optical module, do not touch the gold finger part of the optical module, in order to avoid damage to the optical module; insert the optical module, confirm the optical module puller is attached to the optical module optical port and then inserted; unplug the optical module, first pull out the fiber optic cable, pull the puller to the optical port and about 90 degrees position and then slowly pull out, pull out can not be too hard or puller is not in place to pull out, there may be It may cause damage to the shield of the optical module.
(2) prevent the module optical port pollution
a, try to use high-quality fiber optic connectors;
b, inserted into the optical module fiber patch connector before use, it is best to use high purity alcohol cotton to wipe, to avoid cross-contamination of the optical port due to light jumper end contamination;
c, optical modules to avoid prolonged exposure, temporary non-use of fiber optic patch cords and optical modules not in use must be promptly plugged on the dust cap to avoid dust into the optical module and affect its performance. Dust caps are stored in a dust-proof clean place when not in use;
d, fiber optic connector inserted is horizontally aligned with the optical port to avoid end face and sleeve scratches;
e, the end face of the fiber optic connector to keep clean and avoid scratches.
(3) prevent electrostatic damage
(4) Long-range modules pay attention to light saturation
For long-range optical module, because its average output optical power is generally greater than its maximum input optical power (i.e., optical saturation), so please pay attention to the length of the use of optical fiber, if the conditions are not available and the need for prior commissioning, please be sure to use 10-20dB optical signal attenuator to effectively attenuate the fiber signal strength to ensure that the actual optical power received by the optical module is less than its optical saturation, otherwise it may cause Otherwise, it may cause damage to the important parts of the optical module.
(5) Avoid the mixed use of multimode and single-mode optical fiber
Multimode modules use multimode fiber, single-mode modules use single-mode fiber, mixed with the case of signal loss and other failures.
(6) single-fiber bi-directional modules, to avoid wavelength confusion
Single-fiber bi-directional modules, used in pairs, A device transmitting wavelength and B device receiving wavelength to be the same, wavelength mix-ups will occur in the case of Link failure.
(7) The wrong voltage
1x9 optical module power supply 3.3V and 5V two, SFF SFP optical module power supply only one, for 3.3V, if the wrong voltage supply situation will appear optical path does not work, the voltage increases or even burn the module.
3. Optical module damage common judgment steps
Test whether the optical power is within the range of the indicator requirements, if there is no light or optical power of the phenomenon of small.
Treatment methods.
a, check the wavelength and measurement unit of optical power selection (dBm)
b, clean the fiber optic connector end face, optical module optical port.
c, check whether the fiber optic connector end face is blackened and scratched, fiber optic connector is broken, replace the fiber optic connector to do interchangeability test
d, check whether there is a small bend in the fiber optic connector.
e, hot-swappable optical modules can be re-plugged test.
f, the same port replacement optical module or the same optical module replacement port test.
Optical module in the current optoelectronic products is very commonly used optoelectronic products. Effective protection of optical modules from damage is the work we have to do.
