Theoretical analysis and modeling of a photonic integrated circuit for frequency 8-tupled and 24-tupled millimeter wave signal generation

Abstract

A photonic circuit design for implementing frequency 8-tupling and 24-tupling is proposed. The front- and back-end of the circuit comprises 4×4 MMI couplers enclosing an array of four pairs of phase modulators and 2×2 MMI couplers. The proposed design for frequency multiplication requires no optical or electrical filters, the operation is not limited to carefully adjusted modulation indexes, and the drift originated from static DC bias is mitigated by making use of the intrinsic phase relations of multi-mode interference couplers. A transfer matrix approach is used to represent the main building blocks of the design and hence to describe the operation of the frequency 8-tupling and 24-tupling. The concept is theoretically developed and demonstrated by simulations. Ideal and imperfect power imbalances in the multi-mode interference couplers, as well as ideal and imperfect phases of the electric drives to the phase modulators, are analyzed.

Electro-optic up-conversion mixer amenable to photonic integration

“…Indeed, the drift of bias points in MZMs has been acknowledged as a serious issue and led to a substantial volume of literature on the physical mechanisms responsible [16,17], and its alleviation by sophisticated stabilization mechanisms [18][19][20][21]. Moreover, the present work builds up from recent demonstrations of frequency 8-tupled and 24-tupled millimeter wave signal generation utilizing the same circuit concept [22,23], and analyzes the photonic architecture for the specific application of optical upconversion mixing. Transfer matrices are used to represent the main building blocks in the proposed design, and hence to describe the operation of the entire optical up-conversion mixer.…”

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.…”

“…Frequency octo-tupling can be achieved also by driving the modulator harder (5.37 ≤ m ≤ 5.48) where the 4th harmonics are significantly higher than the carrier. In [10], a DC bias-less, filter-less frequency octo-tupler circuit is proposed, whose performance is not limited by carefully adjusting modulation index, rather it can operate for a wide range of modulation index. In this context, the proposed circuit herein is not superior, as the multiplication depends upon adjusting the modulation index to m 2.4 or 5.37 ≤ m ≤ 5.48, but it is advantageous when one takes into account that in addition to frequency multiplication, it can perform SSB modulation and the proposed circuit needs only four-PM, which is half the number of PM used in [10].…”

“…In [10], a DC bias-less, filter-less frequency octo-tupler circuit is proposed, whose performance is not limited by carefully adjusting modulation index, rather it can operate for a wide range of modulation index. In this context, the proposed circuit herein is not superior, as the multiplication depends upon adjusting the modulation index to m 2.4 or 5.37 ≤ m ≤ 5.48, but it is advantageous when one takes into account that in addition to frequency multiplication, it can perform SSB modulation and the proposed circuit needs only four-PM, which is half the number of PM used in [10]. Although the unused ports of the four MZM in [10] can be combined with another 4 × 4 MMI to obtain the operation of SSB, unlike the circuit proposed herein, it requires the applied RF carrier phases to be changed from 0°, 45°, 90°, and 135°to 0°, 90°, 90°, and 0°and an undesirable waveguide crossover is introduced.…”

Optical millimeter wave signal generation with frequency 16-tupling using cascaded MZMs and no optical filtering for radio over fiber system

“…Hasan et al have utilized array of four phase modulators to generate frequency octupling and 24 tupling [18]. Recently, several frequency 16-tupling techniques have been demonstrated using two cascaded MZMs with two tunable lasers [19], dual parallel MZMs [20], two cascaded dual parallel MZMs [21], and dual stage cascaded MZMs [22].…”