Linearized electrooptic microwave downconversion using phase modulation and optical filtering

Abstract

We propose and demonstrate an electrooptic technique for relaying microwave signals over an optical fiber and downconverting the microwave signal to an intermediate frequency at the receiver. The system uses electrooptic phase modulation in the transmitter to impose the microwave signal on an optical carrier followed by re-modulation with a microwave local oscillator at the receiver. We demonstrate that by subsequently suppressing the optical carrier using a notch filter, the resulting optical signal can be directly detected to obtain a downconverted microwave signal.We further show that by simply controlling the amplitude of the microwave local oscillator, the system can be linearized to third-order, yielding an improvement in the dynamic range.

Linearization of an intensity-modulated analog photonic link using an FBG and a dispersive fiber

“…When the frequency of the input RF signals falls below one half the bandwidth of FBG, the 71st order sidebands will be partially blocked by the FBG, deteriorating the linearization effect and reducing the link gain [14]. Fortunately, an FBG with a bandwidth of as low as 5 GHz may be available [16].…”

“…Signal distortions come from the nonlinearities in the electro-optic modulation and demodulation transfer functions. Even in the single tone case, 3rd order distortion terms m 3 are present in the photocurrent at ω RF [14]. From Eq.…”

Analytical Model for Calculating the Nonlinear Distortion in Silicon-Based Electro-Optic Mach–Zehnder Modulators

“…The objective in that case is to maximize the farthest distortion terms. Many works have been reported about these techniques [27]- [31] using commercial LiNbO 3 modulators. In silicon, we recently reported a photonic mixer with excellent quality parameters, such a 7 dB conversion losses and an error vector magnitude of 8%, for frequency conversion applications [32].…”

Photonic angle-of-arrival and time-dif ference-of-arrival measurement based on dual drive 1 \times 2 MZM

“…Photonics offer many advantages in processing microwave signals because it has an intrinsic feature of wide instantaneous bandwidth, which is suitable for the generation, transmission, control, and processing of wideband microwave signals [1−4] . Recent studies have proposed a number of approaches for frequency estimation measurement [5−10] , spectral analysis [11] , and up/down-conversion of wideband microwave signals [12] . However, to date, only a few approaches have measured the critical parameters, such as the AOA and the time-difference-of-arrival (TDOA) [13,14] .…”