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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 19, Iss. 19 — Sep. 12, 2011
  • pp: 18479–18485

Rectangular QPSK for generation of optical eight-ary phase-shift keying

Guo-Wei Lu, Takahide Sakamoto, and Tetsuya Kawanishi  »View Author Affiliations

Optics Express, Vol. 19, Issue 19, pp. 18479-18485 (2011)

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Quadrature phase-shift keying (QPSK) is usually generated using an in-phase/quadrature (IQ) modulator in a balanced driving-condition, showing a square-shape constellation in complex plane. This conventional QPSK is referred to as square QPSK (S-QPSK) in this paper. On the other hand, when an IQ modulator is driven in an un-balanced manner with different amplitudes in in-phase (I) and quadrature (Q) branches, a rectangular QPSK (R-QPSK) could be synthesized. The concept of R-QPSK is proposed for the first time and applied to optical eight-ary phase-shift keying (8PSK) transmitter. By cascading an S-QPSK and an R-QPSK, an optical 8PSK could be synthesized. The transmitter configuration is based on two cascaded IQ modulators, which also could be used to generate other advanced multi-level formats like quadrature amplitude modulation (QAM) when different driving and bias conditions are applied. Therefore, the proposed transmitter structure has potential to be deployed as a versatile transmitter for synthesis of several different multi-level modulation formats for the future dynamic optical networks. A 30-Gb/s optical 8PSK is experimentally demonstrated using the proposed solution.

© 2011 OSA

OCIS Codes
(060.0060) Fiber optics and optical communications : Fiber optics and optical communications
(060.1660) Fiber optics and optical communications : Coherent communications
(060.5060) Fiber optics and optical communications : Phase modulation

ToC Category:
Fiber Optics and Optical Communications

Original Manuscript: July 22, 2011
Revised Manuscript: August 14, 2011
Manuscript Accepted: August 14, 2011
Published: September 6, 2011

Guo-Wei Lu, Takahide Sakamoto, and Tetsuya Kawanishi, "Rectangular QPSK for generation of optical eight-ary phase-shift keying," Opt. Express 19, 18479-18485 (2011)

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