Method and apparatus for cascade connection of a couple of phase modulators to generate light alternation quarter-phase phase-shift keying code

Abstract

The invention discloses a generation method of a light interleaving four phase phase-shift keying code and a device thereof, which belong to a new device of an all-optical communication network of the next generation and are used in envelope fluctuations after an optical signal transmission system and an optical mark exchange network reduce phase modulation code pattern signals and pass a band-pass filter. Two lines of data signals are interleavingly loaded into a continuous wave optical signal through two phase modulators to produce the light interleaving four phase phase-shift keying code. By adopting the invention, the 180 degrees phase jump problem of the existing optical QPSK signal code type can be solved; the produced light has high spectrum efficiency of the light interleaving four phase phase-shift key code; the problem of 'diagonal transition' can be eliminated; furthermore, the maximum value of the phase change is 90 degrees, not 180 degrees of the QPSK signals. The invention provides a light interleaving four phase phase-shift keying code generation device which comprises the main parts of a continuous wave laser light source, two phase modulators, a digital signal source and an electric delayer; the light interleaving four phase phase-shift keying code generation device is simple in structure, stable in performance and low in price.

Description

(1) Technical field [0001] The invention belongs to a novel device of the next-generation all-optical communication network, and is used in an optical signal transmission system and an optical label switching network to reduce the envelope fluctuation of a phase-modulated pattern signal passing through a band-pass filter. (2) Background technology [0002] At present, different code patterns have been used for signal transmission in high-speed optical communication systems, and the first report of optical quadrature phase-shift keying (QPSK) as a vector modulation format (vector modulation format) applied to optical communication systems was in It was made public at the OFC meeting in 2002. After the code modulation format was proposed, it has aroused extensive interest of researchers. One of the signs is that at the "Workshop on Advanced Modulation Formats" conference held in San Francisco in June 2004, various studies were conducted on the application of this code modulat...

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Problems solved by technology

But any transition of the four signal points of QPSK is possible: 00-11, 11-00, 10-01, 01-10, all transitions on the diagonal (on the constellation diagram), resulting in a 180-degree transition point

After transmission, this will cause the largest envelope fluctuation, and the envelope fluctuation will expand the spectrum of the signal and cause interference to adjacent channels, so the currently proposed QPSK signal pattern is not an ideal for optical communication systems. Modulation

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