The application of the VCSEL laser source in the network

At present, the development of Gigabit Ethernet, especially Gigabit Network Development Based on optical fiber very quickly. Now almost all the network chooses is the optical fiber Gigabit network. The standard and product of the optical fiber based Gigabit Ethernet (10G) is also being developed and will soon be available.

We know that the current laser source is mainly LED and traditional laser light source two. Due to the defects of the power and scattering of LED light source, it is widely used in the short distance local area network. Figure 1 is an example of an application. In the optical fiber interface and due process errors will produce malalignment, due to the LED light source is diffuse in the whole fiber, so malalignment will cause a great loss, and the laser energy is concentrated mainly in the center of the optical fiber, so the loss caused by malalignment is very small.

Many users still choose LED light source, which is mainly due to the higher prices of traditional laser light source, thereby affecting its application. For example, 1/3 or more of the price of a switch or router that uses a conventional laser source as a light source is paid for the light source. In the past two years, the introduction of a new laser source makes this situation has been greatly improved. This is known as the VCSEL laser light source.

VCSEL vertical cavity surface emitting laser, is a type of semiconductor laser micro tube two. The utility model is different from the traditional edge lighting technology used on the current communication equipment. Compared with the traditional laser light source, VCSEL laser source has many advantages. On the wafer manufacturing efficiency is high; manufacturing method can use the standard together with other components manufacturing (without pre manufacturing); packaging and testing is done on the wafer; high transmission speed and low energy consumption, less affected by temperature. In a word, VCSEL is a new type of laser source with good performance and low cost.

Because of these characteristics of VCSEL light source, it has been more and more widely used, especially in Gigabit Ethernet applications. At present, many network interconnection devices, such as switches and routers, can provide the port of VCSEL light source, so that the price of routers and switches. Currently the most widely used is the 850nm VCSEL multimode laser light source. So what is the effect of the light source on the fiber optic link? There are two categories of users to consider. A class of users is to install a new network, including optical fiber wiring. Another class of users is to upgrade the network has been opened. No matter what kind of users, we need to consider the use of Gigabit Ethernet technology on the backbone network. At the same time, the network equipment. It is better to use the light source which is consistent with the network equipment when testing the optical cable link. For example, a network device uses a LED light source to test the same type of light source. This is because the performance requirements of the cable link are different because of different light sources. For example, the use of LED light source tester to test the optical cable link, the test results are. At this time, the use of traditional laser light source or VCSEL light source of the network equipment can use the optical cable link. However, if the LED light source is used to test the optical cable link and the result is not passed, then can the network device using the VCSEL light source use the optical fiber link? The answer is uncertain. If the VCSEL is used as a tester for the light source, the result is that the network device can be connected directly. This is because the performance of the VCSEL light source is much better than LED. Although the use of LED light source test is not passed, but the VCSEL light source can pass. Some users use the LED light source to test the optical cable link has not been passed, and then spend a lot of time and cost to find fault, and even re laying optical cable link. In fact, without any changes can be used directly, because the network device used by the light source is VCSEL. It's much better than the LED light source. But only by testing can we know. In a popular example, it is possible to use a load of 10 tons of cars to detect a bridge carrying a load of 10 tons. If the test does not pass, the bridge must not be allowed to pass the weight of 10 tons of cars. However, whether it can pass 10 tons of the following car? At present the company network cable tester DSP4X00 series, can choose VCSEL laser source test adapter, to directly test the cable link. The option also includes the traditional laser light source at 1310 wavelength test.

At present, the test of optical fiber link is a complex and challenging problem. The reason is that many types of fiber. Single mode and multi-mode. And there are a variety of wire diameter specifications. There are many types of light sources used, namely, LED, CSEL and conventional laser light sources. In addition, the light source has different wavelengths. In the optical cable testing standards and LAN standards and optical fiber cable installation standards. It is because of the above reasons that the test of optical cable link is very complex. Therefore, it is a good way to test the optical fiber link with the specific network application, and use the corresponding light source and the corresponding network standard.