Electro-optic up-conversion mixer amenable to photonic integration

Abstract

A novel electro-optical up-conversion mixer architecture comprising four electro-optical phase modulators situated in the arms between an interconnected 1 × 4 distribution tree and a complementary 4 × 2 combination tree is proposed. The distribution and combination trees are based on multi-mode interference couplers (MMI). The novelty lies in the use of the intrinsic phase relations between the MMI ports to realize a broadband and free of drift design requiring no static phase shift elements. A transfer-matrix approach is followed to represent the main building blocks in the proposed design, and hence to describe the operation of the entire optical up-conversion mixer. The concept is demonstrated by computer simulations. A single side-band modulation with carrier suppression is obtained at the output of the proposed architecture, which is in agreement with the analytical development. Scenarios considering both ideal and imperfect power balances and phase relations in the MMIs, as well as imperfect phase relations of the electrical drives to the phase modulators are analyzed.

A full‐duplex dual‐polarization QPSK in a digital radio‐over‐fiber system

“…At the output of the SSB block, the intermediate frequency signal is translated into a single‐sideband at the frequency of 2 f RF from the emitting wavelength λ 2 of the laser source. After transmission through a fiber optic span, the optical SSB signal reaches the central office and is detected using an optical coherent receiver . It has been verified that the fiber‐optic link can operate perfectly even with a weak input RF signals as low as −55 dBm for the back‐to‐back system …”

Dual-function photonic integrated circuit for frequency octo-tupling or single-side-band modulation

“…The difference between the circuits proposed have largely concerned variations of the static optical and electrical phase shifts required or the implementation of an equivalent circuit using standard Mach-Zehnder modulators (MZM) rather than individual phase-modulators (PM) as the basic building brick. It has been shown in recent works [10][11][12] how to use the intrinsic phase relations between the ports of splitters and combiners and specifically multi-mode interference (MMI) couplers to implement substantially the static optical phase shifts required by these circuits, thereby avoiding the need to apply static DC bias to the electrooptic modulators and the associated drift issues that otherwise require complex stabilization circuitry [13,14]. The aim of this Letter is to show that relatively minor modifications or additions to a particular circuit in the generalized MZM class [11] may enable the reuse of much of the circuit for distinct applications, heralding the prospect of a first-general purpose microwave photonic integrated circuit.…”

“…It has been shown in recent works [10][11][12] how to use the intrinsic phase relations between the ports of splitters and combiners and specifically multi-mode interference (MMI) couplers to implement substantially the static optical phase shifts required by these circuits, thereby avoiding the need to apply static DC bias to the electrooptic modulators and the associated drift issues that otherwise require complex stabilization circuitry [13,14]. The aim of this Letter is to show that relatively minor modifications or additions to a particular circuit in the generalized MZM class [11] may enable the reuse of much of the circuit for distinct applications, heralding the prospect of a first-general purpose microwave photonic integrated circuit. While LiNbO 3 technology offers a mature solution to the small scale integration of MZM structures, this work anticipates photonic integrated circuits based on Si and/or InP material integration platforms emerging as the preferred choice for photonic integration [15].…”

“…An OHDSR of 35 dB and EHDSR of 20 dB are obtained for 2°phase error in the RF drive signals. More detail analysis of these operations may be found in references [10,11].…”

Integrated Optical SSB Modulation / Frequency Shifting Using Cascaded Silicon MZM

“…FFICIENT single side band suppressed carrier (SSB-SC) modulation technology for frequency conversion or shifting is a growing need and fundamental to radio frequency photonic systems. Starting from the very first demonstration [1] of an integrated SSB modulator based on a Ti-diffused LiNbO3 optical waveguide circuit driven by an in-phase (I) and quadrature (Q) signal at 2 GHz, there has been a plethora of publications [2][3][4][5][6][7][8][9] describing different techniques for obtaining the desired functions. All the architectures presented in references [1][2][3][4][5][7][8][9] use circuits of Mach-Zehnder Modulators (MZM).…”