We propose an optica1-terahertz link using a triply-resonant photonic molecule and discuss its applications for terahertz signal detection and synthesis using traditional RF and optical techniques. Our design is a low-cost alternative to THz frequency generation via microwave drives and can be operated in both continuous-wave and pulsed regimes.

We present a compact high-speed electro-optical modulator based on a thin-film lithium niobate platform for continuous-wave wireless-to-optical signal conversion, which collects terahertz signals between 82-380 GHz directly from free space via a large aperture on-chip antenna.

Terahertz technologies offer unique advantages for communication, sensing, and imaging, yet integrated platforms struggle to perform efficiently in this range. Thin-film lithium niobate, a nonlinear photonic platform, enables compact, broadband, and high-speed terahertz sources through efficient frequency conversion. In this talk, I present our progress on developing subterahertz continuous-wave sources on lithium niobate chips, aiming to bridge the gap between electronic and photonic systems for next-generation terahertz integration.

We present frequency-tunable, photolithography compatible superconducting microwave resonators designed for integration with electro-optic devices. We demonstrate >500 MHz of tuning with a bulk permanent magnet and > 1 00 MHz of tuning with planar coils under moderate (<5 mT) magnetic fields.

This work presents a superconducting microwave resonator that is both frequency tunable and compatible with photolithography. This design is well-suited for integration with electro-optic devices. We demonstrate tuning ranges exceeding 500 MHz, using a bulk permanent magnet, and 100 MHz, using planar coils, under moderate magnetic fields (below 5 mT).

We present a photonic integration method combining flip-chip bonding and photonic wirebonding. This approach enables a 'mother' substrate to host 'child' chips from diverse platforms, fostering seamless integration for multi-functional photonic architectures.

We present an integrated photonic chip based on a thin-film lithium niobate platform that measures the autocorrelation function of coherent and non-coherent states of the terahertz electric fields with sub-cycle temporal resolution.

This work presents a dual-tone source on thin film lithium niobate for generating a tunable carrier frequency at the terahertz domain. The system exhibits stable carrier generation above 100 GHz with sub-kHz linewidth and tunability of over 5 GHz.

The terahertz (THz) frequency region (0.1-10 THz) between microwaves and infrared, holds significant potential across various fields such as communication, sensing, and spectroscopy. Conventional THz systems for broadband emission and detection remain bulky and complex, making the development of a fully integrated, miniaturized THz system on a chip a significant challenge. Lithium niobate is an excellent material for THz emission and THz detection for its high second order nonlinearity and low optical losses in the near-infrared range [1]. Recently, thin-film lithium niobate (TFLN) platform has shown great potential for integrated THz systems [2-4]. Here, we develop a single device with dual functionalities based on the TFLN platform, capable of both THz emission and detection. Operating at the zero-dispersion wavelength (~1310 nm) for conventional single mode fiber, the system maintains short pulse duration without the requirement for complicated dispersion compensation methods, enabling broadband THz emission and detection from 0.1 to 2.5 THz.

We present a dual-functional integrated chip realized on a thin-film lithium niobate platform, serving as both terahertz emitter and detector, enabling broadband emission and detection from 0.1 to 2.5 THz.

We discuss recent progress in miniaturizing terahertz devices, facilitated by integrated photonic circuits. We show these provide ways to engineer dispersion, achieve field enhancement and realise complex functionalities on a single chip.

We present an optically packaged thin film lithium niobate device. We show that this packaged device is capable of cryogenic operation and is resistant to extreme thermal shock.

Recent research revealed that in resonators with deep subwavelength gaps coupled to two-dimensional electron gases, propagating plasmons lead to energy leakage, hindering polaritonic resonance. This study introduces plasmonic reflectors to create an artificial energy stopband, confining terahertz-range plasmons and recovering polaritonic resonances. Using this approach demonstrates a normalized coupling ratio of 0.36, enabling the observation of polaritonic resonances not seen without plasmonic reflectors.

We present emission up to 3 THz from a phase-matched terahertz-optical photonic circuit, featuring a co-planar metallic cavity traversed by an optical rib waveguide and a dipolar antenna for efficient out-coupling of terahertz waves.

Terahertz science and technology is possibly now at an inflection point where integrated photonic circuits become increasingly viable sources and detectors of such high-frequency radiation. Generation in both second order [1] and third order [2,3,4] nonlinear waveguides and architectures thereof has exploited either optical rectification or microcomb generation with subsequent optical-to-terahertz conversion at a uni-travelling carrier photodiode. These initial demonstrations showcase a possible route towards miniaturized terahertz chips that are seamlessly integrated with photonics.

We demonstrate tunable dispersion compensation of femtosecond pulses at telecom wavelengths for broadband Terahertz generation in 7.5-meter fiber link using a Silicon prism pair. The prism pair enhances the amplitude of the THz E-field in InGaAs photoconductive antenna by up-to factor 5. As part of the fiber system, we employ a Mach-Zehnder modulator for pump intensity modulation at MHz frequencies and determine the dynamic range in electro-optic sampling. The performance is compared to direct modulation of the InGaAs antenna at the same frequencies. Our work establishes high compatibility between fiber and broadband THz systems.

It was recently demonstrated that, in deep subwavelength gap resonators coupled to two-dimensional electron gases, propagating plasmons can lead to energy leakage and prevent the formation of polaritonic resonances. This process, akin to Landau damping, limits the achievable field confinement and thus the value of light-matter coupling strength. In this work, we show how plasmonic reflectors can be used to create an artificial energy stopband in the plasmon dispersion, confining them and enabling the recovery of the polaritonic resonances. Using this approach we demonstrate a normalized light-matter coupling ratio of ^Ω_ω^R₀ = 0.36 employing a single doped quantum well with a resonator’s gap size of 250 nm equivalent to λ/3000 in vacuum, a geometry in which the polaritonic resonances would not be observable in the absence of the plasmonic reflectors.

We will present experiments on ultrastrongly coupled, strongly subwavelength resonators in arrays down to single element. We will discuss the limitations of the planar resonators approach when employing extremely subwavelength gaps and we will present the new developments towards single-object, few electrons ultrastrongly coupled systems.

Photoconductive antennas (PCAs) have proven to be an excellent platform for efficient broadband terahertz (THz) generation and detection, especially in THz spectroscopy and sensing applications. However, since sub-picosecond optical pulses are required for pumping the PCAs, dispersion-induced pulse broadening hampers a full integration of such THz systems to optical fiber links and limits their compactness and portability [1]. In addition, modulation of PCAs is routinely done at 10-100 kHz, while MHz frequencies have not been well investigated. In this work, we demonstrate high-frequency modulation of THz pulses up to 75 MHz with a Mach-Zehnder modulator (MZM) by controlling the intensity of each single optical pump pulse of a 100 MHz femtosecond laser, while biasing the InGaAs PCA with V = 10 V DC. We compare the generated THz signals to direct PCA modulation at the same frequencies. To compensate the dispersion of fiber and free-space components, we implement a tunable Si prism pair and 1.2 m-long dispersion compensating fiber (DCF) in order to suppress the second-order dispersion of the complete system. As shown in the setup in Fig. 1 (a), one prism can be translated to fine-tune the pre-chirp induced into the 1550 nm pump pulse. In contrast to conventional prism setups and grating mirrors, which exploit angular dispersion, we utilize material dispersion since it has the opposite chirp sign and compensates the fiber dispersion at 1550 nm. The prisms exhibit nearly unitary transmission thanks to incidence at Brewster angle.

In this work, by combining an asymmetric Silicon immersion lens configuration and a complementary resonator design, far-field transmission measurement of a single subwavelength split-ring resonator, ultra-strongly coupled to inter Landau level transitions in a single quantum well, is resolved. The highest coupling is 60%, achieved for only 2000 coupled electrons for a single resonator on an InSb quantum well. This technique can be useful to characterize the complex conductivity of micron-sized samples, such as exfoliated graphene or transition metal dichalcogenide flakes, in the THz domain.