Frederic van Dijk

60 GHz radio-over-fiber technologies for broadband wireless services [Invited]

Some of the work carried out within the European integrated project Integrated Photonic mm-Wave Functions for Broadband Connectivity (IPHOBAC) on the development of photonic components and radio-over-fiber technologies for broadband wireless communication is reviewed. In detail, 60 GHz outdoor radio systems for >10 Gbits/s and 60 GHz indoor wireless systems offering >1 Gbit/s wireless transmission speeds are reported. The wireless transmission of uncompressed high-definition TV signals using the 60 GHz band is also demonstrated.

Coherent terahertz photonics

We present a review of recent developments in THz coherent systems based on photonic local oscillators. We show that such techniques can enable the creation of highly coherent, thus highly sensitive, systems for frequencies ranging from 100 GHz to 5 THz, within an energy efficient integrated platform. We suggest that such systems could enable the THz spectrum to realize its full applications potential. To demonstrate how photonics-enabled THz systems can be realized, we review the performance of key components, show recent demonstrations of integrated platforms, and give examples of applications.

Monolithic dual wavelength DFB lasers for narrow linewidth heterodyne beat-note generation

We have developed a dual wavelength DFB laser for the generation of a widely tunable microwave signal. In order to obtain a narrow linewidth of the generated signal, we have focused the development of the source on the reduction of the linewidth of each generated wavelengths. The best results were obtained with a device using 2500 µm long DFB sections that generated linewidths narrower than 300 kHz. Beating the two wavelengths from this chip on a photodetector resulted in a beat note having a linewidth of 600 kHz. This microwave signal could be tuned from 3 to 20 GHz with a linewidth kept below 1 MHz.

95 GHz millimeter wave signal generation using an arrayed waveguide grating dual wavelength semiconductor laser

We report the generation of a 95 GHz carrier frequency by optical heterodyning of two wavelengths from adjacent channels from an arrayed waveguide grating-based multiwavelength laser. The extended cavity structure of the device provides low phase noise and narrow optical linewidth, further enhanced by the intracavity filter effect of the arrayed waveguide grating. We demonstrate that the generated RF beat note, at 95 GHz, has a -3  dB linewidth of 250 kHz. To the best of our knowledge, this is the narrowest RF linewidth generated from a free-running dual-wavelength semiconductor laser. The device is realized as a photonic integrated circuit using active-passive integration technology, and fabricated on a multiproject wafer run, constituting a novel approach for a compact, low-cost dual-wavelength heterodyne source.

Integrated InP Heterodyne Millimeter Wave Transmitter

A monolithically integrated tunable heterodyne source designed for the generation and modulation of sub-terahertz signals is demonstrated. Distributed feedback lasers, semiconductor optical amplifier amplifiers, passive waveguides, beam combiners, electro-optic modulators, and high-speed photodetectors have been monolithically integrated on the same InP-based platform. Millimeter wave generation at up to 105 GHz based on heterodyning the optical tones from two integrated lasers in the integrated high bandwidth unitraveling-carrier photodetector has been demonstrated. This photonic integrated chip was used in a 100-Mb/s OOK wireless transmission experiment using the integrated amplitude modulator.

Photonic generation for multichannel THz wireless communication

We experimentally demonstrate photonic generation of a multichannel THz wireless signal at carrier frequency 200 GHz, with data rate up to 75 Gbps in QPSK modulation format, using an optical heterodyne technique and digital coherent detection. BER measurements were carried out for three subcarriers each modulated with 5 Gbaud QPSK or for two subcarriers modulated with 10 Gbaud QPSK, giving a total speed of 30 Gbps or 40 Gbps, respectively. The system evaluation was also performed with three subcarriers modulated with 12.5 Gbaud QPSK (75 Gbps total) without and with 40 km fibre transmission. The proposed system enhances the capacity of high-speed THz wireless transmission by using spectrally efficient modulated subcarriers spaced at the baud rate. This approach increases the overall transmission capacity and reduces the bandwidth requirement for electronic devices.

Optical injection locking of monolithically integrated photonic source for generation of high purity signals above 100 GHz

A monolithically integrated photonic source for tuneable mm-wave signal generation has been fabricated. The source consists of 14 active components, i.e. semiconductor lasers, amplifiers and photodetectors, all integrated on a 3 mm(2) InP chip. Heterodyne signals in the range between 85 GHz and 120 GHz with up to -10 dBm output power have been successfully generated. By optically injection locking the integrated lasers to an external optical comb source, high-spectral-purity signals at frequencies >100 GHz have been generated, with phase noise spectral density below -90 dBc/Hz being achieved at offsets from the carrier greater than 10 kHz.

Behavioral modeling of radio-over-fiber links using memory polynomials

A behavioral, nonlinear radio-over-fiber (RoF) link model considering memory effects with low complexity is presented. Model validation against experimental results is demonstrated, with the effect of the memory length on the fitting accuracy being studied.

All-Optical Clock Recovery for 40-Gb/s MZM-Generated NRZ-DPSK Signals Using a Self-Pulsating DBR Laser

All-optical clock recovery for the nonreturn-to-zero differential phase-shift-keying (NRZ-DPSK) modulation format is demonstrated experimentally at 40 Gb/s using a self-pulsating distributed Bragg reflector laser. The use of a Mach-Zehnder modulator to generate the NRZ-DPSK signal yields a modulated signal spectrum with a weak clock tone. The self-pulsating laser is able to directly recover a clock signal with a root-mean-square timing jitter of 760 fs and an extinction ratio of 13 dB; a preprocessing stage to enhance the clock tone is not required. The timing jitter of the recovered clock signal is characterized for different values of the input signal optical signal-to-noise ratio and for varying amounts of waveform distortion due to polarization-mode dispersion.

Phase Noise Investigation of Multicarrier Sub-THz Wireless Transmission System Based on an Injection-Locked Gain-Switched Laser

In this paper, we propose a multi-carrier THz wireless communication system using an injection-locked gain-switched laser as an optical comb source. The phase noise of the 192 GHz signal resulting from the beating of two optical comb lines is theoretically analyzed and experimentally examined. Moreover, a three channel, 10 Gbaud QPSK THz signal is generated, and transmission over 40 km standard single mode fiber (SSMF) is experimentally demonstrated.