High-frequency exciton-polariton clock generator

Abstract

Integrated circuits of photonic components are the goal of applied polaritonics. Here, we propose a compact clock generator based on an exciton-polariton micropillar, providing optical signal with modulation frequency up to 100 GHz. This generator can be used for driving polariton devices. The clock frequency can be controlled by the driving laser frequency. The device also features low power consumption (1 pJ/pulse).Optical computing is an important long-standing goal in the field of photonics 1,2 . Different approaches were used in the field during the last 70 years, including analog optical computing 3,4 , combined electro-optical circuits 5 , photonic neural networks 6 , and digital optical computing 7-9 . Integration of the photonic components raises several key problems linked with miniaturisation, such as the protection from the parasite reflections, potentially solved by the recently emerged topological photonics 10,11 . But one of the main problems has been linked with the high powers required for optical switching via the Kerr nonlinearity or other mechanisms used in nonlinear optics [12][13][14] . One option to solve this issue can be to reduce the size of the non-linear cavities, such as it is done for nano-lasers 15 . Another option is to enhance nonlinearities using the strong light-matter coupling 16,17 which allows to use the significant interactions between the matter part of the eigenmodes 18-20 .Cavity exciton-polaritons 17 (polaritons) are a good example of such promising platform showing an increase by a factor of 10 4 with respect to the ordinary Kerr nonlinearity in standard inorganic semiconductors 20,21 as well as in 2D monolayer materials 22,23 and perovskites 24 . Thanks to these properties, many non-linear polariton devices have already been proposed and implemented [25][26][27][28][29] . Such devices exhibit low operation powers and fast switching times. They can be assembled into logical circuits capable of functioning at very high operating frequencies. However, in order to be correctly tested and to be ultimately useful, these circuits have to be driven not by an external pulsed (or even cw) laser, as it is typically the case in experiments, but by an integrated "clock generator" able to provide the expected operation frequency.In electronics, the clock generators always contain a nonlinear element (such as an inverter), which is often combined with a resonant element (such as a quartz crystal) for frequency stability. The most well-known example is the Pierce oscillator 30 . In general, the non-linear circuits used for generating oscillations date back to the beginning of the XX century 31 and are called multivibrators. They are often based on bistable nonlinear elements exhibiting two possible stationary outputs for a given single input. Biasing the bistable element makes impossible for it to remain in these stationary states, and thus the element is constantly switching between a) Electronic mail: dmitry.solnyshkov@uca.fr the two at a well defined rate. It is therefore logical t...

Lotka-Volterra population dynamics in coherent and tunable oscillators of trapped polariton condensates

“…Moreover, non-Hermitian twolevel systems of polariton condensates could potentially model the open Bose-Hubbard dimer [14], PT -symmetric physics [15,16], and nonlinear Josephson effects such as macroscopic self-trapping [17,18]. Recently, these sys-tems have been theoretically proposed as clock generators under resonant laser excitation [19], and to realize propagating domain walls in extended condensates through mode competition [20]. It is therefore of quite some interest to be able to generate and control macroscopically occupied dissipative two-level systems to investigate the aforementioned possibilities.…”

Reservoir optics with exciton-polariton condensates

“…Scanning across pump power parameters, we demonstrate a departure of the condensate steady state, resembling the linear Schrödinger dynamics, into a stable limit cycle state characterized by multiple spectral peaks and rapid (≈ 252 GHz) density oscillations in the focal region. This result holds promises for polaritonic clock generators in integrated circuits [53]. We next studied the condensate behaviour in a simpler setup consisting of only a single lens shaped pump driven above threshold.…”

Reservoir optics with exciton-polariton condensates

“…Scanning across pump power parameters, we demonstrate a departure of the condensate steady state, resembling the linear Schrödinger dynamics, into a stable limit cycle state characterized by multiple spectral peaks and rapid (≈ 252 GHz) density oscillations in the focal region. This result holds promises for polaritonic clock generators in integrated circuits [48]. We next studied the condensate behaviour in a simpler setup consisting of only a single lens shaped pump driven above threshold.…”