to inspect radiation zones in nuclear power plants from a safe distance, and in many medical applications, such as in endoscopy, which is a flexible, bendable tube containing several "optical fibers". When it is slipped into the patient's mouth, nose,
gastrointestinal tract, and other parts of the heart that cannot be seen from outside the body, the doctor is able to see internal changes through the endoscope,
reducing the need for risky surgery.
Fiber optics have a wide range of applications, in addition to being used for communication
way, it can also be used to make endoscopes and other medical devices, fiber optic sensors or fiber optic decorations, transportation, night vision
sensors metrics measurement and control engineering microscopy, microscopy, machine vision, illumination, imaging, health,
charge-coupled device (CCD) automotive. etc. So it is gradually replacing copper wire as the main communication medium.
New Technology for Fiber Optic Applications
In the late 1970s, fiber optic technology began to enter the commercial field, fiber optics
Some of the intrinsic characteristics of the advantages (such as the absence of noise and interference and high transmission bandwidth, etc.)
Makes it an ideal transmission medium for a variety of applications. Vertical trunks for high rate
systems implemented in optical fiber have become the preferred design option for network designers
. The investment in optoelectronic devices on these vertical backbones is usually
compensated for in terms of bandwidth and confidentiality. In the horizontal workspace, however,
the use of fiber optics was long neglected. In the early 1980s, end users began installing fiber-optic
cable to the information outlets of their workstations in the hope that cost-effective
fiber-optic products would become available in the future, but the horizontal cables installed by most users operated in the "dark" mode because the system's optoelectronic devices could not reach the required bandwidth and confidentiality.
Cannot achieve the required bandwidth and are too expensive.
Users lost interest in fiber-optic horizontal-area cabling due to the lack of cost-effective fiber-optic products. Recently, due to changes in cabling standards and advances in optoelectronics
, cables, connectors, and bandwidth escalation, many
users have begun to reconsider fiber-to-the-desk as an alternative to copper in horizontal cabling systems
. Below we discuss some of the technical issues and
standards associated with this.
Development of fiber optic connector technology
In recent years, fiber optic technology, such as fiber optic connectors, fiber optic cables and optoelectronic devices, has
developed significantly. Changes in the physical size and form factor of fiber optic connectors (e.g., ST,
SC interfaces) have been of interest to product developers and end users.
Since many LAN applications require only two fibers (one for
transmitting and one for receiving), a
duplex fiber optic connector is required in most cases. Dual-conductor fiber optic connectors will always be much larger than the RJ45 receptacles used for unscreened
shielded twisted-pair (UTP) cabling systems, and considering the density of connectors on the patch panel, unscreened twisted-pair (UTP) cabling systems
will be more attractive. At workstation information outlets, dual-conductor fiber optic connectors also
have serious space issues - it's difficult to
design panels and modules that can support more than 2 dual-conductor fiber optic connectors on a single-hole American Standard mounting box.
To solve this problem, several manufacturers have developed small form factor dual
core fiber optic connectors that allow fiber optic connectors to compete in size with RJ45 connectors
. Several of these connectors are innovative in design and greatly reduce
the time required for fiber termination. Some vendors have also partnered with optoelectronic device manufacturers to produce couplers in the same form factor to arrange LE
D/PIN pairs, supporting the production of new fiber optic connectors. However, the current EI
A/TIA TR41.8 recommendation states that SC Duplex fiber optic connectors will remain the standard fiber optic connector at the workstation end, while any fiber optic connector can be used at the intercom end.
The EI/TIA TR41.8 recommendation also states that SC Duplex fiber optic connectors will remain the standard fiber optic connector at the workstation end, while any fiber optic connector can be used at the intercom end. Regardless of what TR41.8 thinks about this issue, the development of small
inch fiber optic connectors has resulted in fiber optic connectors and UTP connectors that are roughly equivalent in size
inch.
Developments in Fiber Optic Technology Short wavelengths are defined as 850nm, while long wavelengths are defined as 1300nm. Table 1 gives
the separate operating windows for the two wavelengths of multimode fiber. These operating windows are
determined by the attenuation characteristics of the fiber. However, after 1996, advances in fiber
manufacturing technology have improved the attenuation characteristics of optical fibers, allowing them to be used in the
entire 720nm to 1370nm band. This is important for the development of wavelength division multiplexing
(WDM) systems.
Table 2 gives a comparison of the characteristics of 62.5nm and 50nm fibers in specific wavelength bands.
Both fiber core sizes can be used for LANs. It is clear from Table 2 that the bandwidth of 5
0nm fiber is wavelength-independent, which is a major advantage of 50nm fiber, however
There is a 3dB energy degradation associated with the use of 50
nm fiber due to the difference in core size from the commonly used 62.5nm fiber. If the energy is large enough to accommodate this 3dB attenuation in the worst-case link
cases, then its increased bandwidth can support
more applications (such as Gigabit Ethernet) with a lot of bandwidth left over
Since the signal attenuation of 62.5nm fiber is
maximal in the 820nm to 920nm band, why is it still operating in this band? why does it still operate in this band? Simply, this is
because optoelectronic devices (LEDs and PINs) are
very inexpensive compared to their long-wavelength counterparts, at about 30% of their price, making the use of short-wavelength optoelectronic
devices very important.
Development of fiber optic devices
Light-emitting diodes (LEDs) and PIN photodiodes are the most commonly used light source and light detector in short-wavelength multimode optical
fibers. LEDs can support data rates up to 125 Mbps. ordinary PINs are affected by noise. To minimize the effect of noise, a mutual impedance amplifier is added to the PIN package, and this optical detector
is the PIN-FET assembly. The advantage of this device is that it is less expensive, but LE
Ds can support lower transmission rates, making it difficult to use them in high-speed data transmission
Lasers and snow bouncing photodiodes (APDs) are another class of light sources and detectors used in fiber-optic systems.
These devices can support very high speeds, and they can support very high data rates. These devices can support very high data transmission rates.
APDs have high quantum efficiency, which makes them ideal for "
low-light" applications. However, both devices are complex, and keeping them operating stably
demands a high degree of electronic and temperature control. It is this complexity
that makes them expensive to apply, thus limiting the use of
One exception to the "laser principle" is the vertical
cavity surface-emitting laser (VCSEL), which operates in the short wavelength band. Its advantage over LEDs is that it is a semiconductor laser that can support transmission rates of up to 2Gbps. Moreover, it
has a low drive current, an output optical power of up to 1mW (0dBm), and a spectral width of less than
0.5nm. More importantly, it requires less circuitry, which greatly simplifies
the design requirements and reduces the cost of the device.VCSELs are also superior to LEDs in terms of packaging, as they don't require prisms, and several VCSELs can be packaged in a single base. Several VCSELs can be placed on the same substrate
to form an array, making them ideal for ribbon fiber and WDM applications. These advantages make VCSELs an ideal light source, and the superior bandwidth performance of VCSELs
makes multimode fiber one of the best choices for Gigabit Ethernet applications. Table 3 gives a comparison of LEDs and VCSELs
Fiber Optic Standards
Users and network designers are increasingly concerned about electromagnetic interference/Radio Frequency Interference (
EMI/RFI), bandwidth, link distances, data security, and network failures
. The only medium that meets all of these criteria simultaneously is optical fiber.
The introduction of the TIA/EIA TSB-72 standard in 1995 and the formation of the TIA Fiber Optic
Local Area Networks Subcommittee (FOLS) Short Wavelength Consortium in 1998 are testament to this.
TSB-72 is a standard for centralized fiber-optic cabling systems.TSB-72
Allows for fiber-optic cabling distances of up to 300 meters, allowing network designers to take advantage of the long transmission distance to centralize network electronics (such as routers, hubs, and switches
) into a single equipment room. p>) into a single device room. This architecture gives users a way to transition from the current
previously ****-enabled bandwidth environment to a switched environment. The centralized network architecture
increases the flexibility of the network, simplifies network expansion, moves, changes, and
management, reduces network downtime, and most importantly, it significantly reduces
installation costs
100 Mbps Fast Ethernet is the fastest growing type of LAN application
.1995 The IEEE802.3u 100BASE-FX standard defines the fiber-optic medium
Fast Ethernet standard.The 100BASE-FX standard uses the signaling
coding (4B5B coding) method of the FDDI standard and the physical medium signaling portion. It uses long-wavelength
long (1300 nm) optoelectronics, which are
much more expensive than short-wavelength (850 nm) optoelectronics (described
above). As a result, the IEEE is currently developing a new standard, 100BA
SE-SX, and a number of interested vendors have formed the Short Wavelength Consortium
in the first quarter of 1998. Its mission is to develop standards for Fast
Ethernet using low-cost, short-wavelength fiber optic devices. Note that this is very important. Its short-term goals are:
1. Cost reduction, i.e., using common optoelectronic devices, achieved by using short-wavelength optoelectronic devices (LEDs and PINs) that have been developed
issued
2. The 100BASE-SX standard will be compatible with the 10BASE-FL Standard compatible 3.. Connectors can be used.4. Easy upgrade to 100Mbps. Media Conversion Consider a fiber-to-the-desktop solution that not only requires optical
fiber information outlets (ST, SC, flat or angled, etc.) and fiber optic distribution enclosures (ST
, SC, wall-mounted, cabinet-mounted, pull-out, etc.), but also needs to
Consider fiber optics directly to the desktop.
So, in many fiber-to-the-desktop solutions, many technical people
will encounter the cost of network equipment will increase a lot of such a very realistic
problem, that is, we usually use the computer network card will be replaced by fiber-optic cards,
ordinary hubs, RJ45 outlets can no longer be used, but is purely a hub, the RJ45 outlet, and so on, and so on. can no longer be used, but are replaced by hubs with pure fiber optic
outlets. Due to fiber-optic network card and optical export hub prices
very expensive, resulting in the rise of the cost of the entire system, so fiber to the desktop now
in the country is still basically only on paper.
A very practical way to achieve fiber to the desktop is to use media converter
Converter (i.e., photoelectric converter). This device makes LAN upgrades very simple
and protects the investment in copper LAN equipment. I hope the above is informative and helpful to you!