A. Scavennec

Monolithic integration of an InP based polarization diversity heterodyne photoreceiver with electrooptic adjustability

In this paper we describe the monolithic integration, in the InP/InGaAsP material system, of a polarization diversity optical heterodyne receiver. The study concerns different components which are part of the device: polarization splitters, adjustable 3 dB TE and TM directional couplers, waveguide integration with PIN photodiodes, modal tapers, and JFETs. All these devices are developed in a compatible integration approach, as building blocks of the overall device. Eventfully, two circuit demonstrators-a polarization-diversity optical circuit integrated with two balanced-PIN pairs and a coupler integrated with a balanced-PIN pair and JFET amplifier-are presented. These two circuits show very good characteristics in terms of internal loss, rejection ratio, electrical bandwidth, and input noise, similar to hybrid circuits. This work paves the way for the use of complex integrated photoreceivers for system application. >

InGaAs/InP monolithic photoreceivers for 1.3-1.5 um optical fiber transmission

The sensitivity of InGaAsIInP monolithic photoreceivers for 1 . 3 - 1. 5 . tm has been largely improved in recent years now reaching the sensitivity figures of hybrid InGaAs pin/GaAs MESFET receivers. The characteristics of an integrated InGaAsfJnP pin-JFET front-end based on MBE growth and diffused junctions are analysed. The results are used to illustrate some pending problems oflnGaAs FETs requiring future improvement.

AlInAs/GaInAs SAGM-APD

The fabrication and performance of a graded avalanche photodiode structure with a separate GaInAs photo-absorption layer and AlInAs avalanche region to achieve a pure electron injection are discussed. The quality of AlInAs as the avalanche region has been evaluated by measuring responsivity, response time, and excess noise factor. The 3 dB bandwidth and the excess noise factor correspond to beta / alpha approximately 0.3 in pure AlInAs, decreasing to about 0.1 for an AlInAs/GaInAs MQW structure.<<ETX>>

InP electronic preamplifiers in photoreceiver applications

Transmission over fibre networks at 1.3-1.5 /spl mu/m is presently developing very rapidly in telecom and TV broadcasting networks, and is actively researched for high speed interconnects and microwave transmission. In most cases, conventional photoreceivers are used, associating InGaAs/InP p-i-n or APD photodetectors and Si or GaAs-based hybrid or integrated preamplifiers. The major progress experienced in InP microelectronics during the last 10 years, illustrated by the record cut-off frequencies of InP transistors, now allows the fabrication of low-noise preamplifiers, suitable for the monolithic integration of wideband high-sensitivity photoreceivers or for compact, low consumption photoreceiver arrays. In this paper, after a short review of the available devices and integration schemes being presently developed, some illustrative results on AlInAs-InGaAsP-InP HFET preamplifiers used in hybrid or integrated photoreceivers are presented.

Waveguide-fed PIN-HFET receiver at 2.5 Gbit/s integrated on InP

We report the monolithic integration of a building block, a waveguide-fed photoreceiver, comprising a semiconductor waveguide, a PIN photodiode, and a 3 stage low noise preamplifier, based on 0.5 /spl mu/m gate length high performance HFETs. Internal sensitivities better than -27dBm at 2.5Gbit/s and -25dBm at 5Gbit/s have been measured.

Photodétectors for 1.3 μln - 1.55 μnl fiber optic transmissions: State of the art

In the optical fiber télécommunication systems, the emission and reception modules contain optoelectronic components such as laser diodes and photodiodes. Beside the laser whose task and complexity are obvious, the photodiode, the mechanism of which is quite straightforward, becomes a sophisticated device when optimized for 1.3–1.55 µm fiber window. For photodetection, the photodiode is always associated to a preamplifier obtained from a transistor. For a given link, the performances of the receiver straightly depend on those of the photodiode and of the transistor. Different types of photodetectors are suitable for 1.3 µm and 1.55 µm transmissions. This paper surveys the different semiconductors materials and device structures encountered nowadays, pointing out the respective merits of each solution. Comparisons between photoreceivers outline the importance of matching the photodiode to the transistor, whether dealing with hybrid or monolithic circuits.AnalyseDans les systèmes de télécommunication par fibre optique, les fonctions d’émission et de réception sont assurées par des composants optoélectroniques, typiquement des lasers et des photodiodes. Face au laser dont le rôle et la complexité sont évidents, la photodiode, composant au principe de fonctionnement à priori simple, devient un dispositif complexe lorsqu’il est optimisé pour les télécommunications dans la bande 1, 3–1,55 µm. En photodétection, la photodiode est toujours associée à un préamplificateur réalisé à partir d’un transistor. Des performances individuelles de ces deux composants dépendent celles de la tête de photoréception adaptée à un type de liaison donné. De fait, il existe plusieurs types de photodétecteurs adaptés aux liaisons à 1,3 μ5;m et 1,55 μm. Cet article présente les différents matériaux semiconducteurs et les différentes structures de photodiodes utilisées actuellement, en soulignant les avantages respectifs des différentes solutions. Certaines comparaisons entre têtes de photoréception mettent en avant Vimportance de l’adaptation du couple photodiode transistor, que ce soit en circuits hybrides ou circuits monolithiques.

Limitation des performances des photodétecteurs à avalanche GaAIAsSb par effet tunnel

AnalyseLes liaisons optiques à grande distance de haut débit exigent des détecteurs rapides à faible bruit adaptés aux fenêtres de transmission 1,3 ou 1,55 μm des fibres optiques à verre de silice. Le système GaAlAsSb/GaSb peut répondre à ce besoin, et des photodiodes ont été récemment réalisées avec, comme zone active, le ternaire GaAlSb ou bien le quaternaire GaAlAsSb qui offre l’avantage d’avoir un paramètre de maille accordé sur celui du substrat GaSb [1 à 6]. Malheureusement, ce système a toujours présenté des courants d’obscurité élevés attribués soit à des courants de surface [4], soit à des courants de type tunnel [6]. Dans cet article, les auteurs montrent que la composante du courant inverse à l’obscurité est effectivement dominée dans une large gamme de polarisations par un effet tunnel bande à bande, ou assisté par pièges, ce qui limite la valeur du facteur de multiplication optimal et augmente la puissance équivalente du bruit.AbstractThe high rate long distance fiber optical communications require rapid low noise detectors adapted to wavelengths 1.3 or 1.55 μm. GaAlAsSb/GaSb is a suitable system for this need. Recently, the authors have obtained photodiodes with ternary GaAlSb or quaternary GaAl AsSb as an active layer. Quaternary alloys were latticematched to GaSb substrate [1–6]. But, this system presented large reverse dark currents attributed either to surface currents or tunneling currents [6]. In this paper, we prove that in a large range of polarization the reverse dark current is dominated by band to band tunneling or defect assisted tunneling. This limits the value of the optimum multiplication factor and increases the noise equivalent power.