Low-cost analog fiber optic links for in-house distribution of millimeter-wave signals

Abstract

In this article, analog fiber optic links (radio-over-fiber, RoF, links) are presented as a flexible, low-cost solution for in-house distribution of millimeter-wave (mmw) signals. Mode-locked laser diodes (MLLD) serve as inexpensive mmw sources for the downlink distribution of mmw signals across an optical fiber link. We compare the robustness of direct and external RF modulation for such MLLD-based RoF systems, whereas the error vector magnitude (EVM) of the received symbols serves as a figure of merit. On the eve of 60 GHz WLAN standardization, we experimentally investigate the transmission of narrowband WLAN (IEEE 802.11a) signals in the millimetric range at moderate data rates. We also demonstrate broadband transmission of multi-band orthogonal frequency-division multiplexing (MB-OFDM) ultra-wideband (UWB) european computer manufacturers association (ECMA 368) signals in the 60 GHz band for data rates of up to 480 Mbps.

Analog link performance of mode-locked laser diodes in the 60 GHz range

“…The generation of the millimeter-wave (MMW) carrier signals, either at the central station or the remote access point, remains a crucial issue. Mode-locked laser diodes (MLLD) have been proposed as cost-efficient, easy-to-package solution and multi-gigabit transmission using MLLD has been demonstrated recently ( [1], [2]). A comprehensive link analysis in terms of RF system design parameters (i.e.…”

Optical Heterodyning for Reduction of Chromatic Dispersion Sensitivity in 60 GHz Mode-Locked Laser Systems

“…Fig. 3, it can be seen that the MMW power reaches a second maximum at 2140 m after traveling a further distance of 2070 m along the SMF for which the modes become again in phase [6]. This periodicity length is directly linked to the 58.37 GHz spacing between laser modes and to the chromatic dispersion of the SMF [3].…”

“…As can be seen in this figure, the photodetected output MMW power reaches its first maximum after meters of transmission. This initial shift is precisely due to the effect of laser chirp and dispersion [6]. From this observation, the dispersion in the SMF is required to access the maximum MMW power.…”

“…For the simulation, the 30 most powerful modes were taken into account, as the contribution of the other low power modes does not have a significant impact on the results [6]. As can be seen in this figure, the photodetected output MMW power reaches its first maximum after meters of transmission.…”

“…The L range for which the MMW power remains at maximum value tightly depends on those effects. This paper examines the possibility to have higher margin in L by taking advantage of dispersion and mode multiplicity [6]. Chromatic dispersion effects are well known for RoF MMW systems with single-mode lasers and induce RF fading [7].…”