Pilot Photonics (Ireland)

We demonstrate a hybrid external cavity laser incorporating an integrated side coupled Fabry-Perot (SC-FP) resonator realised on a silicon nitride platform and coupled to a semiconductor optical amplifier. The SC-FP resonator achieves loaded quality factors of up to 6.5 × 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> with on-resonance reflectivity reaching 57%. The hybrid laser exhibits multi-wavelength emission aligned to the SC-FP resonances, with multiple longitudinal modes of the hybrid cavity competing within each resonance. When isolating single resonances, we observe coherent pulse trains with corresponding radiofrequency linewidth as narrow as ∼3 kHz. The system spontaneously generates multiple identical pulse profiles within the laser cavity, effectively multiplying the repetition rate. These results establish SC-FP resonators as promising wavelength-selective reflectors for compact, multi-wavelength hybrid laser systems with potential applications in frequency comb generation for telecommunication and precision spectroscopy.

We experimentally demonstrate <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$8 \times 225$</tex> Gbit/s PAM-8 transmission utilizing a 200 GHz -spaced DFB laser array and a quantum-dot SOA-PIN configured receiver. The BER performances of all channels stay under the 20% overhead SD-FEC threshold of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2 \times 10^{-2}$</tex> after 1 km transmission employing a truncated T-spaced VNLE.

We present the results of the detected voltage distribution of a quantum random number generator (QRNG) based on a photonic integrated circuit comprising a semiconductor laser, delay interferometer and photodetector. We find that the integrated QRNG system behaves as expected for a QRNG from discrete gain-switched laser sources, especially exhibiting all of the peculiarities of the random voltage distribution and behaving as previously demonstrated for a discrete optical component setup. The biggest advantage of having all of the components integrated into a single chip is that only electrical connections are needed to operate the system, without the need for tricky and expensive optical alignment to external circuitry. We supply results showing that a random bit stream created from the random numbers passes the NIST statistical test suite tests, thus demonstrating the feasibility to generate random numbers via quantum means at gigabit/s rates from a single photonic integrated circuit. All of our results are backed by numerical simulations.

Due to their simplicity, dual-wavelength-modulation (dual-λ-mod) photonic transmitters are an attractive alternative to conventional heterodyne systems for mm-wave/THz signal generation. In contrast to what has been reported in the literature, the authors of this manuscript believe that dual-λ-mod systems based on DSB-C modulation are subjected to power fading, rendering them useless for high-speed mm-wave/THz communications. To solve this, we propose a dual-λ-mod system based on SSB-C modulation. Using a GS laser, a 60-GHz SSB-C dual-λ-mod system transmitting 2.5-GBd 16-QAM signals is demonstrated. A PD-input-power penalty of just 2.8 dB is measured with respect to the conventional heterodyne transmitter at a BER of 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> for optical B2B and 10 km fiber transmission.

In this paper, we demonstrate a novel multi-section directly modulated laser transmitter for upstream operation in the application of time wavelength division multiplexing (TWDM) architecture. The photonic integrated circuit (PIC) is fabricated using a regrowth-free process that favors simplified and fast manufacturing. The PIC is based on a master-slave configuration, with an addition of a variable optical attenuator (VOA) section between them, and a semiconductor optical amplifier (SOA) at the output. The VOA enables control of the optical injection from the master to the directly modulated slave laser improving the transmission performance. The integrated SOA section at the output is used to boost or turn off the optical output power of the transmitter, thereby enabling burst mode operation. Experimental results show that the PIC can be tuned to four wavelength channels on a 100 GHz frequency grid. We also demonstrate that each channel achieves error-free performance (bit error ratio < 10e <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> ), when modulated with 10 Gbps signal and transmitted over 25 km and 50 km fiber. The SOA-based output disable feature of the PIC delivers more than 60 dB attenuation.

Coherent optical communication systems require laser sources with high power and narrow linewidth. Single wavelength laser sources are used today while for future capacity scaling multiwavelength sources are expected to be employed. This paper describes recent developments in integrated tunable and comb lasers assemblies targeting coherent optical communication and other applications.

A novel reconfigurable photonic integrated transmitter, enabling dynamic resource allocation and sharing, is proposed. Architecture, functionality and a deployment scenario are discussed. Preliminary work on machine learning methods for controlling the device are also presented.

A PIC transmitter for application in TWDM passive optical networks is demonstrated. The device generates four 100 GHz-spaced channels and features an integrated section for chirp control that enables error-free transmission of 10 Gb/s OOK data over 50 km of fiber.

As the demand for wireless data transmission increases, there is a push towards the adaptation of new spectral bands, which can provide the required capacity to satiate this demand. These include millimeter wave (mmW) and even terahertz (THz) signals. One of the main challenges faced at such extremely high frequencies, is the generation and manipulation of the signals. Since the electronic approach suffers from low efficiency and high losses, the photonic generation of the mmW and THz signals becomes increasingly attractive. In this paper, we demonstrate a photonically-integrated device capable of generating an optical frequency comb (OFC), which in turn could be used for the optical generation of high-frequency (mmW and THz) signals. A complete OFC characterisation, to demonstrate the performance and the limitations of the device, in terms of the frequency tuning range and the spectral quality of the generated signal, will also be presented. Finally, methods that could be used to expand the frequency comb, in order to generate THz frequencies will also be discussed.

Energy-efficient athermal bias current procedures based on thermal-tuning is demonstrated for a PIC composed of 2 lasers in a master-slave configuration, achieving mode-hop free wavelength stability of 750 MHz over a temperature range 10–60 °C.