C-band Single Wavelength 100-Gb/s IM-DD Transmission over 80-km SMF without CD compensation using SSB-DMT

Over 300-km Transmission of 25 Gb/s Optical SSB NPAM-4 Signal with Electronic Dispersion Pre-compensation and Interference Mitigation

“…The Nyquist filter with a roll-off factor of 0.01 is applied to generate NPAM-4 sequence and its Hilbert term is generated by Hilbert transform. In Case-I, we use the baseband signal m(t) and its Hilbert term as the driving signals for DDMZM, which has no change with a conventional optical SSB transmitter [4]. In Case-II, the sum and difference of the baseband NPAM-4 signals are used as the driving signals.…”

“…Optical single side-band (SSB) modulation has been proposed to alleviate the power fading effect and double the spectra efficiency. Generally, two main methods, complex modulation with a pair of Hilbert transform signals and vestigial sideband filtering (VSB), have been proposed to generate a SSB signal [3,4]. All of these works concentrate on the improvement of CD tolerance in the C-band, which makes full compensation of the CD desirable [1].…”

Carrier-assisted differential detection

“…After square-law detection using a single-ended photodiode (PD), signals can be extracted from the signal-carrier beating term, and the optical field is reconstructed without using a local oscillator. In the recent decade, various schemes of field recovery with direct detection have been investigated [12][13][14][15][16][17][18][19][20][21][22][23] . Since direct detection generally provides only intensity information, until now, signals have been mainly restricted to the single sideband (SSB) modulation format in various proposed intensity-only detection schemes 14 .…”

2 × 2 multiple-input multiple-output optical–wireless integration system based on optical independent-sideband modulation enabled by an in-phase/quadrature modulator

“…Here, it is worth noting that s1 and s2 can have identical or different baud rates and adopt identical or different modulation formats, including QPSK, 8-ary quadrature-amplitude modulation (8QAM), 16QAM, and 64QAM and so on. As we know, a complex sinusoidal radio-frequency (RF) source, equivalent to a real sinusoidal RF source with its positive or negative spectrum removed by a Hilbert-transform phasing method, has a one-sided spectrum and is typically used for SSB modulation [19][20][21][22]. Thus, by means of simultaneous digital upconversion, s1 is carried by positive frequency f s1 after mixing with the complex sinusoidal RF source at positive frequency f s1 , while s2 is carried by negative frequency −f s2 after mixing with the complex sinusoidal RF source at negative frequency −f s2 .…”

“…A freerunning laser source offers a continuous-wave (CW) lightwave at frequency f c for the optical input of the I ∕Q modulator. As we know, an electrical SSB signal can be linearly converted to an optical SSB signal when its real and imaginary parts are used to drive an I ∕Q modulator [19][20][21][22]. We can consider that, in our proposed system, it is the real and imaginary parts of the linear combination of two independent electrical SSB signals that are used to drive the I ∕Q modulator, which leads to simultaneous linear conversion of these two electrical SSB signals to the optical domain.…”