Modulation and Switching Architecture Performances for Frequency Up-Conversion of Complex-Modulated Data Signals Based on a SOA-MZI Photonic Sampling Mixer

Abstract

A theoretical and experimental performance analysis of a Semiconductor Optical Amplifier -Mach-Zehnder Interferometer (SOA-MZI) photonic sampling mixer used as a frequency up-converter is presented employing Switching and Modulation architectures. An active mode-locked laser, generating 2 ps-width pulses at a repetition rate equal to 10 GHz, is used as a sampling source. An optical carrier intensity modulated by a sinusoidal signal at 1 GHz is up-converted to 9 GHz and 39 GHz. High Conversion Gains (CGs) of about 15 dB are demonstrated for the frequency conversion to 9 GHz using both architectures, whereas up to 4 dB and 9 dB for the conversion to 39 GHz employing Switching and Modulation architectures, respectively. Small-signal equations for the up-converted signal in both architectures are formulated and developed, which permit to quantify the CG from closed-form expressions. The numerically calculated CG values are in very good agreement with those obtained experimentally. The validated equations are subsequently employed to explain the performance differences between the two architectures in terms of the CG. Furthermore, signals modulated by QPSK and 16-QAM complex modulation formats at different baud rates are up-converted from 750 MHz to 9.25 GHz and 39.75 GHz and their Error Vector Magnitude is evaluated and compared. The maximum bit rate that meets the Forward Error Correction (FEC) limit is achieved using the Modulation architecture. It is 1 Gbps and 512 Mbps for QPSK and 16-QAM modulations, respectively.

Repetition rate performance for frequency mixing of four simultaneous QPSK signals based on a SOA-MZI photonic sampling mixer

“…The sampling signal at various repetition rates, ranging from 7.8 to 19.5 GHz, is generated by an optical pulse clock source. [11][12][13] This source provides an optical pulse train of 10 ps full-width at half-maximum pulses. Its electrical spectrum shows harmonics at H n ¼ nf sk .…”

“…A semiconductor optical amplifier Mach-Zehnder interferometer (SOA-MZI), used as a sampling mixer to accomplish frequency mixing in standard and differential modes, 11,12 is an integrated all-optical switch. The SOA-MZI differential configuration displays preferable performance, such as a conversion gain, compared with the SOA-MZI standard configuration.…”

SOA-MZI photonic sampler with a post-distortion linearization technique

“…1 illustrates the principle of operation of the post-distortion linearization method in a SOA-MZI. In this method, the function of sampling is obtained using a modulation architecture presented for the first time in [17] and in detail in [23]. In the SOA-MZI, a sampling pulse train of instantaneous power P C , center wavelength λ C , repetition rate f C and equal amplitude pulses generated by a mode-locked laser, is applied at input C, while a sinusoidal signal to be sampled of instantaneous power P A , modulation index MI, center wavelength λ Α and frequency f A is applied at input A.…”

“…The use of the Modulation architecture [23] means that the sampling signal with a repetition frequency f C is only amplified, so f C can be very high due to the high optical amplification bandwidth of the SOA, despite the dynamics of the SOA carriers. On the other hand, the signal to be sampled, at the frequency f A , must be below the cutoff frequency of the XPM process, which depends on the dynamics of the SOA carriers.…”

“…Photonic sampling employing a SOA-MZI has been used for the application of photonic microwave mixing in [17][18][19][20][21][22][23], since the SOA-MZI is an all-optical module which uniquely combines a low excitation power, a high extinction ratio and a high switching efficiency with the simultaneous signal amplification [24,25].…”