A novel free-space coupling system combined with a multi-core fiber enables up-scaling to a record space-division-multiplexed (SDM) channel number of 19. We achieve 305-Tb/s transmission over 10.1 km using 19-SDM, 100-WDM PDM-QPSK signals.

19-core fiber transmission of 19×100×172-Gb/s SDM-WDM-PDM-QPSK signals at 305Tb/s

High-speed control of lightwave using electrooptic (EO) effect is investigated in this paper. Agile optical frequency shift can be achieved by optical single-sideband (SSB) and frequency-shift-keying (FSK) modulators, where high-speed optical phase-shift-keying (PSK) signals can also be generated by using FSK/SSB modulators. We also describe ultrahigh extinction ratio optical intensity modulation (IM) technique for two-tone lightwave signals with high spurious suppression, which is useful for photonic microwave and millimeter-wave generation. In addition, we investigated high-order optical sideband generation techniques: quadruple dual-sideband suppressed carrier (QDSB-SC) modulation and reciprocating optical modulation (ROM). Sub-tetrahertz signals can be obtained from lightwaves with high-order sidebands

High-Speed Control of Lightwave Amplitude, Phase, and Frequency by Use of Electrooptic Effect

We report record capacity data transmission at 305 Tb/s over 10.1 km, using space division multiplexing (SDM) with 19 channels. To realize such a large SDM channel number, we fabricated a trench-assisted homogeneous 19-core fiber with average intercore crosstalk of about -32 dB at 1550 nm. We also fabricated a 19-channel SDM multiplexer/demultiplexer using free-space optics with low insertion losses and low additional crosstalk. The data signal transmitted through each SDM channel was 100 wavelength division multiplexing (100 GHz spacing) 2 × 86 Gb/s polarization-division-multiplexed quadrature phase shift keying signals and the spectral efficiency was 30.5 b/s/Hz.

305 Tb/s Space Division Multiplexed Transmission Using Homogeneous 19-Core Fiber

Hybrid optical access networks, integrating fiber-to-the-home (FTTH) and radio-over-fiber (RoF) systems that share a single distributed infrastructure, are promising for future multiservice access networks. The primary concern is to enable RoF and FTTH systems to transmit both radio-frequency (RF) and baseband (BB) signals on a single wavelength over a single fiber. This study experimentally demonstrates simultaneous generation and transmission of a wired-line BB signal and a wireless RF signal on a single wavelength, using one external modulator. The hybrid signals transmitted over standard single-mode fiber (SSMF) do not suffer from periodic performance fading due to fiber dispersion. Following transmission over 50-km SSMF, the power penalties of both RF and BB signals are less than 0.2 dB

/pdf/hybrid-optical-access-network-integrating-fiber-to-the-home-1eyehj9pw1.pdf

Hybrid Optical Access Network Integrating Fiber-to-the-Home and Radio-Over-Fiber Systems

We demonstrate record 109-Tb/s transmission of spatial division multiplexed (SDM) signals over 16.8 km using a seven-core fiber. Each SDM channel contains 97 WDM channels on a 100-GHz grid and 2×86-Gb/s polarization-multiplexed QPSK signals.

109-Tb/s (7×97×172-Gb/s SDM/WDM/PDM) QPSK transmission through 16.8-km homogeneous multi-core fiber

We investigated an integrated optical modulator consisting of two Mach-Zehnder interferometers. The modulator can generate optical signals in various types of modulation formats, which have advantages for long-haul transmission, optical labeling, etc. By using a fabricated versatile optical modulator having traveling-wave electrodes designed for high-speed signals, we demonstrated generation of optical 40Gb/s frequency-shift-keying signals, which can be demodulated by an optical filter. 80Gb/s optical differential quadrature-shift-keying modulation was also demonstrated, where 40Gb/s in-phase and quadrature data were, simultaneously, fed to the modulator.

High-speed optical DQPSK and FSK modulation using integrated Mach-Zehnder interferometers.

A method and device for adequately controlling the DC bias of each of the optical modulating sections of an optical modulator even while the optical modulator is operating in normal mode and even with a simple structure. An optical modulator bias controller (B) for controlling the DC bias of each optical modulating section of an optical modulator (1) is characterized by comprising DC bias application means (3) for applying a DC bias to each of the optical modulating sections, a low-frequency signal superimposing circuit (2) for superimposing a low-frequency signal fB with a specific frequency on a modulating signal b applied to each optical modulating section, optical sensing means (9) for sensing a change of the intensity of the light wave passing through the combining section, and bias control means (4) for extracting the change of the intensity of light corresponding to the low-frequency signal from the optical sensing means and controlling the DC bias application means according to the extracted change of the intensity of light.

Method and device for controlling bias of optical modulator

PROBLEM TO BE SOLVED: To provide a method for bias control over an optical modulator and a device therefor that can properly correct DC biases of a plurality of optical modulation parts during normal operations of an optical modulator with simple structure even if the optical modulator has the plurality of optical modulation parts. SOLUTION: A bias controller B for optical modulator that controls DC biases of the plurality of optical modulation parts of the optical modulator 1 having the plurality of optical modulation parts has a DC bias applying means 3 of applying the DV biases to the plurality of optical modulation parts, a low-frequency signal superposing circuit 2 which superposes a low-frequency signal fB having a specified frequency on a modulation signal (b) applied to the plurality of optical modulation parts, an optical detecting means 9 of detecting variation in the light quantity of light waves passing through a multiplexing part, and a bias control means 4 of extracting light quantity variation corresponding to the low-frequency signal from the optical detecting means and controlling the DC bias applying means according to the extracted light quantity variation. COPYRIGHT: (C)2005,JPO&NCIPI

Method for bias control over optical modulator and device therefor

We propose a high-speed versatile lightwave modulator which can generate on-off-keying, phase-shift-keying and frequency-shift-keying signals. 40 Gbit/s optical FSK modulation was demonstrated by using the modulator consisting of four phase modulators, where frequency deviation was 80 GHz. (2 pages)

40 Gbit/s versatile LiNbO/sub 3/ lightwave modulator

We demonstrate simultaneous optical modulation by frequency shift keying (FSK) and intensity modulation (IM) using a newly developed high-speed FSK modulator, for optical packet systems where payload and label signals are, respectively, in IM and FSK format. The modulator consists of four optical phase modulators, with traveling-wave electrodes to obtain high-speed frequency switching and large frequency deviation in FSK modulation.

Takahisa Fujita

Papers

High-speed optical DQPSK and FSK modulation using integrated Mach-Zehnder interferometers.

Method and device for controlling bias of optical modulator

Method for bias control over optical modulator and device therefor

40 Gbit/s versatile LiNbO/sub 3/ lightwave modulator

Optical FSK/IM Signal Generation Using an Integrated Optical FSK Modulator