Development of a New Approach for High-Quality Quadrupling Frequency Optical Millimeter-Wave Signal Generation Without Optical Filter

Abstract

Abstract-In this paper, we propose a new approach to generate quadrupling-frequency optical millimeter-wave (mm-wave) signal with carrier suppression by using two parallel Mach-Zehnder modulators (MZMs) in Radio-over-fiber (RoF) system. Among the numerous properties of this approach, the most important is that a filterless optical mm-wave at 60 GHz with an optical sideband suppression ratio (OSSR) as high as 40 dB can be obtained when the extinction ratio of the MZM is 25 dB. Simplicity and cost-effectiveness have made this approach a compelling candidate for future wave-division-multiplexing RoF systems.Theoretical analysis is conducted to suppress the undesired optical sidebands for the high-quality generation of frequency quadrupling mm-wave signal. The simulation results show that a 60 GHz mm-wave is generated from a 15 GHz radio frequency (RF) oscillator with an OSSR as high as 40 dB and an radio frequency spurious suppression ratio (RFSSR) exceeding 35 dB without any optical or electrical filter when the extinction ratio of the MZM is 25 dB. Furthermore, the effect of the non-ideal RF-driven voltage as well as the phase difference of RF-driven signals applied to the two MZMs on OSSR and RFSSR is discussed and analyzed. Finally, we establish a RoF system through simulation to verify the transmission performance of the proposed scheme. The Q-factor performance and eye patterns are given.

An Analytical Solution for Fiber Optic Links with Photonic-Assisted Millimeter Wave Upconversion Due to MZM Nonlinearities

“…Special attention is given to the MMW generation which relies on Dual-Parallel MZM (DP-MZM) and exact expressions for the harmonic amplitude dependence on both modulation index and bias point were deduced [9]. Based on such formulation we were able to precisely predict the harmonic distortion suppression ratio within a range of optical modulation index far wider than that used in previous publications [6], [7], [8]. Additionally, a fiber optic spool is inserted on the modulator output for remote transmission.…”

“…An alternative topology ( Fig. 2b) employs two dual drive modulators in parallel, eliminating the use of a third cascade MZM [8]. Both modulators are biased at MITB and the electric input signals on the same modulator are in quadrature, while π out-of-phase from the other modulator.…”

“…Both modulators are biased at MITB and the electric input signals on the same modulator are in quadrature, while π out-of-phase from the other modulator. However, analysis of these topologies have been performed by using approximate methods restricted to small signal regime, where modulation index were arbitrarily limited to low values [6], [7], [8]. This paper is mainly concerned with the modeling of the effect of the MZM nonlinearity on the performance of optical up-conversion.…”

A Cost-Effective Method for High-Quality 60 GHZ Optical Millimeter Wave Signal Generation Based on Frequency Quadrupling

“…The optical method is preferable over the conventional electrical method [13,14]. Various techniques have been developed, such as the stimulated Brillouin scattering (SBS) in optical fiber [15], the use of four-wave mixing in a highly nonlinear fiber (HNLF) [16], and the optical frequency up-conversion using an external modulator, such as LiNbO 3 MZM [17][18][19][20][21][22][23][24][25][26][27]. Compared with these techniques, the optical frequency up-conversion technique could easily generate a stable MMW signal, because of good coherence of two or three generated optical sidebands.…”

“…Thus, only a lower OSSR of 25 dB can be obtained, which degrades the RFSSR between the desired MMW signal and other undesired RF components. In [24], we proposed a new approach to generate quadrupling-frequency optical MMW signal with carrier suppression based on two parallel MZMs, where the OSSR value was about 40 dB.…”