Photonic microwave oscillator based on monolithic DFB lasers with frequency-shifted feedback

International audienceA photonic oscillator, locked to a master RF synthesiser, was built by using a monolithic dual-wavelength DFB semiconductor laser submitted to a frequency-shifted optical feedback. A [3; 10] GHz tuning range is reported, with a phase noise level lower than −70 dBrad2/Hz at a 10 Hz offset from the carrier

Transmission Quality Measurement of Two Types of 60 GHz Millimeter-Wave Generation and Distribution Systems

International audienceIn this paper, we demonstrate and compare experimentally two techniques achieving very high-data-rates (> 1 Gb/s) wireless transmission in the 60 GHz window using radio over fiber (RoF) for reach extension. The first RoF link is based on a 10 GHz vertical-cavity surface-emitting laser and uses a multimode fiber. The radio signal is transported on an intermediate frequency of 4.5 GHz and electrically upconverted to 60 GHz after the optical link. The second uses an optical frequency upconversion from 4.5 to 60 GHz by direct modulation of a mode-locked Fabry-PEacuterot laser whose self-pulsating frequency is 54.8 GHz before transmission over a single-mode fiber. For both techniques, two different types of modulation were tested. The first one was an on-off keying at 1.5 Gb/s and the second one was an orthogonal frequency-division multiplexing-QPSK signal compliant to the IEEE 802.15.3.c prestandard (3.03 Gb/s). Radio propagation performance is also reported

Comparison of two types of 60 GHz photonic millimeter-wave generation and distribution of a 3 Gb/s OFDM signal

International audienceWe demonstrate and compare experimentally two set-ups achieving very high data rate (3 Gbps) wireless transmission in the 60 GHz window, both using Radio-over-Fiber (RoF) for reach extension with OFDM signal compliant to the IEEE 802.15.3.c pre-standard

Laser module based on monolithically integrated MOPAs at 1.5 µm for space-borne lidar applications

Space-borne lidar systems require laser transmitters with very good performance in terms of output power, beam quality, conversion efficiency, long term reliability and environmental compatibility. Atmospheric gas sensing additionally requires spectral purity and stability. Solid state lasers are considered the most mature technology for space lidar applications, at expenses of a relatively large size and low conversion efficiency [1]- [3]. Fiber lasers present very high power levels and very good beam quality, but they require specific attention due to their sensitivity to radiation. In this sense, progresses have been made to develop high power fiber amplifiers for different space applications [4]-[6]. Recently, a new generation of high brightness semiconductor lasers based on tapered geometry has demonstrated relatively high average power levels together with a good beam quality [7]-[10]. These devices are emerging candidates for its direct use in space lidar systems

Coherent terahertz photonics

We present a review of recent developments in THz coherent systems based on photonic local oscillators. We show that such techniques can enable the creation of highly coherent, thus highly sensitive, systems for frequencies ranging from 100 GHz to 5 THz, within an energy efficient integrated platform. We suggest that such systems could enable the THz spectrum to realize its full applications potential. To demonstrate how photonics-enabled THz systems can be realized, we review the performance of key components, show recent demonstrations of integrated platforms, and give examples of applications

Optically-coupled monolithic DFB lasers for the generation of an optically-carried microwave local oscillator

International audienceWe report the experimental realization of a photonic oscillator based on dedicated monolithic dual-wavelength DFB lasers. The oscillator is locked to a master RF synthesizer using an all-optical feedback loop. A [3-10] GHz tuning range is reported, with a phase noise level lower than -55 dBrad2/Hz at 10 Hz from the carrier, instrument-limited

Phase Synchronization of Monolithic Dual DFB Lasers for Microwave Photonics: Experiment vs Model

International audienceThe experimental implementation of optically carried RF signals, in the 1-100 GHz range and beyond, is fundamental for microwave photonics applications. The technique of heterodyning two laser waves provides an interesting alternative to direct modulation of light. Indeed, it allows generating directly a single-sideband signal over an optical carrier, that is inherently insensitive to dispersion in a fiber link. It also features a 100% modulation depth, a broad and continuous tunability. Phase-locking to electronic local oscillators results in optical beatings of very high spectral purity; furthermore, high microwave frequencies 100 GHz) can be reached by suitable multiplication or downconversion techniques (at the expense of a degradation of the phase noise performances

Monolithic dual-wavelength DFB lasers for the generation of optically carriedRF local oscillators

International audienc

High Power, Low RIN, 1.55μm DFB Laser for Analog Applications

In this paper we present a directly modulated laser (DML) designed for high dynamic range analog link [1]. These devices are of great interest for local oscillator distribution or receiver signal remoting. Use of direct modulation is simpler and less expensive than external modulation. To get high power and high efficiency we focused in a first time on the reduction of internal losses in the cavity by decreasing the optical confinement in p-doped indium phosphide (InP). The main constraint was to maintain a sufficient overlap between the optical field and the quantum wells to have a low relative intensity noise (RIN) and a large modulation bandwidth. A compromise has been done on the optical confinement to get in the same time good static performances (power and efficiency) and dynamic performances (RIN and bandwidth). In a second step we tried to reduce the beam divergence and, above all, the ellipticity of the mode. Wafers were processed in dual channel shallow ridge DFB. 1mm long cavities were cleaved and facets were anti-reflective (AR)/ highly reflective (HR) coated. Lasers are mounted p-up on AlN submounts integrating coplanar lines for both DC and RF characterization. Maximum power was 135 mW at 600 mA bias current. The efficiency defined as (Power/(Current-Threshold current)) was up to 0.3 W/A at a bias current as high as 500 mA. RIN measurement has showed a RIN level below -155 dB/Hz on the 40 MHz to 20 GHz range at 450 mA bias current. The modulation bandwidth is up to 6.5 GHz. The side mode suppression ratio (SMSR) exceeds 55dBm. Due to the use of shallow ridge structure linearity of P-I and injection current is very good but the divergence of the beam FHWM of 14°x31°. Future improvements will focus on the reduction of the divergence and the ellipticity of the beam, necessary for a better coupling into an optical fibre

Développement de composants de puissance pour la réalisation de liaisons optiques hyperfréquences de grande dynamique

Les liaisons optiques hyperfréquences présentent aujourd'hui des intérêts pour les oscillateurs opto-électroniques, la radio sur fibre ou le déport à la réception de signaux analogiques. Dans les radars par exemple, le déploiement de liaisons optiques analogiques en lieu et place de câbles coaxiaux est déjà une réalité [1]. Les principaux avantages des liaisons optiques sont la réduction de taille et de masse, les faibles pertes de propagation ou l'immunité électromagnétique et sont dus à l'utilisation de la fibre optique. Depuis une vingtaine d'année, plusieurs types de liaisons optiques hyperfréquences ont été rapportés : modulation directe ou externe, détection directe ou différentielle, avec réduction du bruit [2]. Par rapport aux liaisons à modulation directe, les liaisons à modulation externe permettent généralement de meilleures performances en termes de bande passante, de gain ou de dynamique. Cependant malgré de moins bonnes performances, la compacité et le faible coût des liaisons à modulation directe en font un candidat potentiellement très attractif jusqu'à 6 GHz, en remplacement des câbles coaxiaux. Dans cet article, nous présentons le développement d'une source laser DFB de puissance et d'une photodiode UTC ayant des performances spécifiques pour la transmission de signaux analogiques. Grâce à ces deux composants, nous avons démontré des performances de liaisons optiques en bande L et S à l'état de l'art, alliant fort gain, point de compression élevé et large dynamique (SFDR)