Optical communication systems operating at 10Gbit/s require transceivers of low cost, size and power consumption, driving a "hot" source solution. This paper describes the current status of these "hot" devices for different applications.
10 Gb uncooled FP (Fabry Perot) to be used in conjunction with an EDC (Electronic Dispersion Compensation) receiver for LRM transceivers and 10 Gb 1300nm uncooled EML (Electro-absorption Modulator Laser) for LR transceivers are the devices chosen for LAN (Local Area Network) applications (link up to 10 km. These laser sources can be used for different transceiver form factors: XENPAK, X2 and XFP.
KEYWORDS: Transceivers, Temperature metrology, Modulation, Eye, Laser sources, Lawrencium, Local area networks, Dispersion, Data communications, Laser applications
Optical communication systems operating at 10Gbit/s require transceivers of low cost, size and power consumption, driving a "hot" source solution. This paper describes the current status of these "hot" devices for different applications. 10 Gb uncooled FP (Fabry Perot) to be used in conjunction with an EDC (Electronic Dispersion Compensation) receiver for LRM transceivers and CWDM (Course Wavelength Division Multiplexing) 3.125 Gb DFB for LX4 transceivers are the devices chosen for enterprise network (link up to 300m), which can address the need to transmit data at 10 Gb on the legacy multimode fibers. 10 Gb uncooled 1300 nm DFB (Distributed FeedBack) and 10 Gb 1300nm uncooled EML (Electro-absorption Modulator Laser) for LR transceivers are the devices chosen for LAN (Local Area Network) applications (link up to 10 km). Finally 10 Gb 1550 nm EML are the devices chosen for Metro applications (links up to 40 Km and potentially 80 km), for single wavelength and DWDM (Dense Wavelength Division Multiplexing) applications, so for those applications in which a directly modulated laser can not be used, due to the chromatic dispersion.
All these laser sources can be used for different transceiver form factors: XENPAK, X2 and XFP.
KEYWORDS: Modulators, Eye, Temperature metrology, Modulation, Signal attenuation, Local area networks, Data communications, Transceivers, Laser marking, Absorption
Optical communication systems operating at 10 Gbit/s such as 10 Gigabit Ethernet (GbE) are becoming more and more important, even in Local Area Networks (LAN) and Metropolitan Area Networks (MAN). This market requires optical transceivers of low cost, size and power consumption, driving a need for "hot" transmitter: uncooled DFB lasers directly modulated at 10 Gbit/s for short link (up to 10 km) and high operating temperature integrated (hybrid or monolithic) solution, like laser and electro absorption modulator at 10 Gbit/s, for longer distance (40 - 80 km). The paper describes the current status of these devices for different applications. We will report results on uncooled high speed 1300 nm DFB laser which is capable of being manufactured in high volume at the low cost demanded by the GbE market. Combining an optimized active region based on InGaAsP strained MQW (Multi Quantum Well) and a low parasitic lateral confinement region, we have fabricated 10 Gbit/s directly modulated uncooled DFB lasers which work up to 100°C (chip temperature), with eye diagram perfectly open (showing an extinction ratio > 5 dB @ 100°C), and with Bit Error Rate over 10 km without error floor up to 10-12. We will report the optimization and the results of an electro-abosorption modulator (EAM) based on quantum confined Stark effect in strained multiple quantum wells (MQWs), suitable for 40 - 80 km propagation of 10Gb/s optical signals on standard single-mode fiber at 1550 nm. The MQW structure has been designed and fabricated to obtain high extinction ratio, low insertion loss and negative chirp at 1550 nm, 60°C. Devices demonstrated a contrast ratio of above 10 dB, insertion loss of 5 dB and a negative chirp at 10 Gb/s, 60°C with a voltage swing of 2 V.
The optimization of a 1300nm buried heterostructure(BH)InGaAsP/InP DFB laser for uncooled directly modulated 10Gbit/s operation is described. The development process as well as the key process parameters are discussed and results are presented on an optimized structure. Bandwidths in excess of 10GHz were measured at 90C chip base temperature. Clean open eye diagrams were recorded over the full temperature range, resulting in error free transmission over 40km. To our knowledge the results represent the current state of the art for uncooled BH DFB lasers operating at 1300nm.
Uncooled DFB lasers directly modulated at 10 Gbit/s are a key devices for Optical communication systems operating at 10 Gbit/s, such as 10 Gbit Ethernet, since their effective use in optical transceivers to reduce cost, size and power consumption. The paper describe the current status of these sources (including well assessed InGaAsP MQW and recent progress for AlGaInAs MQW active layers), as well as the Agilent's very recent results. Combining an optimized active region based on InGaAsP strained MQW (Multi Quantum Well) and a low parasitic lateral confinement region, we have fabricated 10 Gb directly modulated uncooled DFB lasers which represent, we believe, the state of art. Our DFB lasers work up to 100 degree(s)C (chip temperature), with eye diagram perfectly open (showing an extinction ratio > 5 dB), and with Bit Error Rate over 10 km without error floor. Up to 90 degree(s)C our DFBs show threshold current as low as 29 mA, optical power as high as 13 mW and meet perfectly 10 Gb scaled Ethernet mask with extinction ratio > 6 dB.
HDBR (Hybrid Distributed Bragg Reflector) laser (also called FGL - Fiber Grating Laser), has been recently demonstrated as low-chirp and potentially low cost lasers emitting at predetermined (ITU-T grid) wavelengths, as well as high quality picosecond pulses laser source. WDM transmission of three densely spaced directly modulated HDBR lasers at 2.6 Gbit/s over 117 km of standard fiber and the direct modulation at 10 Gbit/s have been demonstrated. By using appropriate cavity and grating design, we have realized, for DWDM applications, an HDBR laser that can be directly modulated at 10Gbit/s, while for OTDM systems, we have recently demonstrated a Mode-Locked HDBR laser source, for picosecond optical pulse generation at 10 GHz repetition rate.
Static and dynamic characteristics of three different laser structures, by using the same active structure, have been investigated: (1) conventional BRS (Buried Ridge Structure), (2) p-n multi-junctions (MJ) blocking layers and (3) Fe-doped semi-insulating (SI) InP blocking layer. Good blocking properties in MJ and SI laser structures have been showed by measuring the DC leakage current and the linearity of the power versus current (P-I) curve, also at high operating temperature; SI laser, respect to BRS and MJ structures, has shown a large reduction in parasitic capacitance and a considerable improvement in modulation bandwidth, limited only by dynamic characteristic of active region.
We propose a new accurate method for differential carrier lifetime measurement, in which the laser under test biased below threshold is optically modulated. Experimental results are very reproducible and show very high signal/noise ratio. No additional technological process for the laser under test are required.
3-dB couplers integrated on InGaAlAs/InP grown by Molecular Beam Epitaxy (MBE) have been studied designed and fabricated. The device structure is based on the modal interference principle modelling has been performed by beam propagation and effective index methods and on this basis devices were designed covering a range of geometrical parameters. Devices have been fabricated on single and double heterostructures by wet chemical etching and characterized over the 1. 47-1. 53 im range by a tunable color center laser. Balanced coupling has been observed in several devices with a best one of output balanced within 0. 1 dB over 15 nm.
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