koherenttilähestymistapa

koherenttilähetys is a Finnish term that translates to "coherent transmission" in English. It refers to a method of transmitting information in optical communication systems where the phase of the light wave is preserved and controlled during the transmission. This is in contrast to intensity modulation, where only the amplitude of the light wave is varied.

In coherent transmission, both the amplitude and phase of the optical signal are modulated. This allows for encoding more information into the same bandwidth, leading to higher data rates. Furthermore, coherent detection, which uses a local oscillator laser at the receiver to mix with the incoming signal, can significantly improve the receiver's sensitivity. This is because the local oscillator can amplify the weak incoming signal, making it easier to detect.

The development of coherent transmission has been crucial for the advancement of modern optical networks. It enables the use of advanced modulation formats like quadrature amplitude modulation (QAM) and phase-shift keying (PSK), which significantly increase spectral efficiency. These techniques are essential for meeting the ever-growing demand for bandwidth in telecommunications, data centers, and other high-speed data applications. The ability to preserve and utilize the phase information of light makes coherent transmission a cornerstone of high-performance optical communication.