Low threshold current 1.3-/spl mu/m GaInNAs VCSELs grown by MOVPE

The structure of the conventional contact 1.3-/spl mu/m GaInNAs-GaAs vertical-cavity surface-emitting lasers (VCSELs) was optimized and low threshold current 1.3-/spl mu/m GaInNAs VCSELs grown by metal-organic vapor-phase epitaxy were reported. The idea is to optimize the active region, the doping profiles, and the pairs of p-distributed Bragg reflectors, and the detuning between the emission wavelength and the photoluminescence gain peak wavelength. The continuous-wave 1.0-mA threshold current was achieved for the single-mode VCSEL. For the multiple-mode VCSELs, the below 2-mA threshold currents at 5/spl deg/C-85/spl deg/C , the 1.13-mA threshold current at 55/spl deg/C, and 1.52-mA threshold current at 85/spl deg/C are the best results for 1.3-/spl mu/m GaInNAs VCSELs.     

High-temperature and high-speed operation of a 1.3-/spl mu/m uncooled InGaAsP-InP DFB laser

1.3-/spl mu/m uncooled InGaAsP-InP loss-coupled distributed feedback lasers operating over 10 Gb/s and at 85/spl deg/C were successfully fabricated. In order to achieve high-speed and high-temperature operation simultaneously, the following are thoroughly investigated: modulation-doped and strain-compensated multiple-quantum-well active layers, Fe-doped buried-heterostructure, coupling coefficient of loss-coupled grating, detuning lasing wavelength from the gain peak, and facet coatings. The authors also demonstrate 10 Gb/s transmission with negligible dispersion power penalty over 20 km of nondispersion-shifted fiber at 10 Gb/s for temperatures ranging from 25/spl deg/C to 85/spl deg/C.     

12.5-gb/s direct Modulation up to 115/spl deg/C in 1.3-/spl mu/m InGaAlAs-MQW RWG DFB lasers with notch-free grating structure

Direct modulation at 12.5 Gb/s of 1.3-/spl mu/m InGaAlAs distributed feedback (DFB) ridge waveguide (RWG) lasers with low-resistance notch-free gratings running up to 115/spl deg/C is experimentally demonstrated. It was achieved by the combination of the high differential gain of an InGaAlAs MQW active layer, high characteristic temperature of RWG structure, and low-resistance notch-free grating. Moreover, successful transmission of 10-Gb/s modulated signals over 30-km standard single-mode fiber was achieved with the laser running at up to 115/spl deg/C. These results confirm the suitability of this type of laser for use as the cost-effective light source in 12.5-Gb/s and 10-Gb/s datacom applications.     

High-power ultralow-chirp 10-Gb/s electroabsorption modulator integrated laser with ultrashort photocarrier lifetime

A high-power, ultralow-chirp electroabsorption modulator (EAM) integrated with a distributed-feedback laser diode (EML) having ultrashort lifetime of photogenerated holes in the EAM quantum-well (QW) structure is reported for the first time. A shallow QW structure having a small valence band offset to enhance the sweepout of photogenerated holes was employed as EAM absorption layer. The measured hole lifetimes were 7-11 ps, and the measured frequency chirp (/spl alpha/-parameter) was low or negative at low EAM reverse bias voltages even under high optical output power conditions. Successful 10-Gb/s 80-km normal-dispersion single-mode fiber transmission (chromatic dispersion D=1600 ps/nm) and the record average fiber optical output power (P/sub f/) of +5.3 dBm were achieved at 25/spl deg/C. In addition, semicooled operation of EML at enhanced bit rates has been demonstrated for application in small-form-factor protocol-agnostic optical transceivers. A 10.7-Gb/s 1600-ps/nm transmission was achieved at 45/spl deg/C and P/sub f/=+3.0 dBm.     

Design and fabrication of temperature-insensitive InGaP-InGaAlP resonant-cavity light-emitting diodes

Visible InGaP-InGaAlP resonant-cavity light-emitting diodes with low-temperature sensitivity output characteristics were demonstrated. By means of widening the resonant cavity to a thickness of three wavelength (3/spl lambda/), the degree of power variation between 25 /spl deg/C and 95 /spl deg/C for the devices biased at 20 mA was apparently reduced from -2.1 dB for the standard structure design (1-/spl lambda/ cavity) to -0.6 dB. An output power of 2.4 mW was achieved at 70 mA. The external quantum efficiency achieved a maximum of 3% at 13 mA and dropped slowly with increased current for the device. The external quantum efficiency at 20mA dropped only 14% with elevated temperature from 25 /spl deg/C to 95/spl deg/C. The current dependent far-field patterns also showed that the emission always took place perfectly in the normal direction, which was suitable for plastic fiber data transmission.     

160-gb/s adaptive dispersion equalization using an asynchronous dispersion-induced chirp monitor

This paper describes an adaptive dispersion equalizer (ADE) that uses an asynchronous dispersion-induced chirp monitor and the detailed study of the first demonstration of 160-Gb/s adaptive dispersion equalization. The device successfully equalized the dispersion change over a 40/spl deg/C temperature range (from 5/spl deg/C to 45/spl deg/C) and the dispersion slope of an 80-km dispersion-shifted fiber (DSF). The ADE will enhance the feasibility of 160-Gb/s optical transmission systems.     

Parallel optical transmitter module using angled fibers and a V-grooved silicon optical bench for VCSEL array

We propose an advanced structure of optical subassembly (OSA) for packaging of the vertical-cavity surface-emitting laser (VCSEL) array, using (111) facet mirror of the V-groove ends formed in a silicon optical bench (SiOB) and angled fiber apertures. The feature of our OSA can provide a low optical crosstalk between neighboring channels, a low feedback reflection, and a large misalignment tolerance along the V-groove. We describe the optimized design of fiber angle, VCSEL position, and fiber position. The fabricated OSA structure consists of 12 channels of angled fiber array, 54.7/spl deg/ V-grooves, Au-coated mirrors on (111) end facet of the V-grooves, and flip-chip-bonded VCSEL array on a SiOB. In this structure, the beam emitted from the VCSEL is deflected at the 54.7/spl deg/ mirror of (111) end facet and propagated into the angled fiber. The angled fiber array was polished by 57/spl deg/. Fabricated OSAs showed a coupling efficiency of 30%-50% that is 25 times larger than that obtained from an OSA with a vertically flat fiber array. Our OSA showed large misalignment tolerance of about 90 /spl mu/m along the longitudinal direction in the V-groove. We fabricated a parallel optical transmitter module using the OSA and demonstrated 12 channels /spl times/2.5 Gb/s data transmission with a clear eye diagram.     

Second generation I/SUP 2/L/MTL: a 20 ns process/structure

A high performance, second generation I/SUP 2/L/MTL gate for digital LSI applications with TTL compatibility has successfully been designed, characterized, and demonstrated fully functional over a wide current range and the military temperature range of -55 to 125/spl deg/C. Performance is measured using an in-line five-collector gate having one end injector. The gate performed with the following characteristics at 100 /spl mu/A injector current: /spl beta//SUB U//SUP eff//spl ges/4 for all collectors at 25/spl deg/C and /spl ges/2.5 at -55/spl deg/C, /spl alpha//SUB rec///spl alpha//SUB F//spl cong/0.58 and /spl tau/~/SUB d/=18-20 ns from -55 to 125/spl deg/C, and a speed-power product of 1.4 pJ at 25/spl deg/C. At low injector currents, a constant speed-power product of 0.36 pJ at 25/spl deg/ was obtained.     

Al/sub 0.10/Ga/sub 0.90/As-GaAs microcoolers

GaAs-based microcoolers were fabricated and tested. An Al/sub 0.10/Ga/sub 0.90/As layer grown on GaAs, having a lower thermal conductivity and comparable electrical conductivity to that of the substrate, was employed in the microcooler structure to reduce the heat conduction back from the heat sink. Maximum cooling temperatures of 0.87 /spl deg/C and 2.3 /spl deg/C were obtained at ambient temperatures of 25 /spl deg/C and 100 /spl deg/C, respectively, from 60 /spl times/ 60 /spl mu/m microcoolers.     

Very-low-threshold, highly efficient, and low-chirp 1.55-/spl mu/m complex-coupled DFB lasers with a current-blocking grating

Low-threshold current DFB lasers have been fabricated based on a complex-coupled structure with a current blocking grating. A threshold current as low as 5 mA was obtained, which enabled high temperature operation up to 105/spl deg/C. Asymmetric facet coatings were applied to obtain a high efficiency of 0.3 W/A. The strained InGaAsP MQW active region and the antiphase coupling has resulted in a low modulation chirping. By direct modulation of the device at 2.488 Gb/s and using optical amplifiers, we have demonstrated digital transmission over a 235 km-long standard single-mode fiber with a power penalty of 1.55 dB.     

Field transmission of 8 /spl times/ 170 gb/s over high-loss SSMF link using third-order distributed Raman amplification

This paper reports on the field transmission of N/spl times/170-Gb/s over high-loss fiber links using third-order distributed Raman amplification (DRA) in a commercially operated network of Deutsche Telekom. It gives an overview of the key technologies applied for the realization of an 8 /spl times/ 170 Gb/s (1.28 Tb/s) dense wavelength division multiplexing (DWDM) system demonstrator and summarizes long-haul transmission experiments with terabit-per-second capacity over European fiber infrastructure. Third-order DRA enabled repeaterless transmission of 1 /spl times/ 170 Gb/s and 8 /spl times/ 170 Gb/s over links of 185- and 140-km field fiber, respectively. Including an additional 25 km of lumped standard single-mode fiber (SSMF) at the end of the span, a total loss of 61 and 44 dB, respectively, was bridged.     

Highly reliable and high-yield 1300-nm InGaAlAs directly modulated ridge fabry-Perot lasers, operating at 10-gb/s, up to 110/spl deg/C, with constant current swing

Transceivers for 300-m multimode links, based on a serial 10-Gb/s laser source and incorporating a receiver based on electronic dispersion compensation (EDC), are creating the first high-volume application for a 10-Gb Fabry-Perot (FP). A highly reliable and high-yield uncooled ridge FP laser is presented. The device shows excellent power characteristics in the 25/spl divide/150/spl deg/C temperature range with very high T/sub 0/ (95 K in the temperature range 0/spl divide/85/spl deg/C and still 78 K at 150/spl deg/C). Outstanding dynamic performances are also shown: 6 dB of extinction ratio can be achieved up to 110/spl deg/C by using a constant current swing of 50 mA. Because of their enhanced performances, these devices have enabled single temperature setting of the optical module, leading to a significant test cost reduction.     

Room-temperature laser emission of GaInNAs-GaAs quantum wells grown on GaAs (111)B

In this work, we present room-temperature laser emission at 1.206 /spl mu/m from GaInNAs-GaAs quantum-well (QW) laser diodes (LDs) grown on misoriented GaAs (111)B substrates for the first time. Details of the structure and the molecular beam epitaxial growth of the lasers are discussed. We found that the postgrowth rapid thermal annealing increased the optimum emission, while the in situ self annealing effect in these QWs is almost negligible. The optimum annealing cycle (30 s at 850/spl deg/C) is comparable to that found for the cladding-free GaInNAs single QW samples grown on GaAs (111)B. Finally, the optical and electrical characterization of these LD devices is presented. The LDs show a room-temperature threshold current density of 2.15 kA/cm/sup 2/, with a differential quantum efficiency of 37%, under pulsed conditions.     

100/spl deg/C 10 Gbit/s directly modulated InGaAsP DFB lasers with Ru-doped semi-insulating buried heterostructure

A directly modulated 1.3 /spl mu/m InGaAsP DFB laser with a simple buried structure using Ru-doped semi-insulating InP is presented. The high relaxation oscillation frequency of 10 GHz was obtained at 95/spl deg/C. Clear eye openings under 10 Gbit/s direct modulation were achieved from 0 to 100/spl deg/C.     

Two-step laterally tapered spot-size converter 1.55-/spl mu/m DFB laser diode having a high slope efficiency

We demonstrate a two-step lateral tapered 1.55-/spl mu/m spot-size converter distributed feedback laser diode (SSC DFB LD) having slope efficiencies as high as 0.457 and 0.319 mW/mA measured at 25 /spl deg/C and 85 /spl deg/C, respectively. The SSC DFB LD fabricated by using a nonselective grating process has a double core waveguide structure including a planar buried heterostructure type active waveguide and a ridge type passive waveguide. The fabricated SSC DFB LD operates at 1.553-/spl mu/m wavelength and shows a far-field pattern in horizontal and vertical directions of 7.3/spl deg/ and 11.6/spl deg/, respectively.     

Study on high-temperature performances of 1.3-/spl mu/m InGaAsP-InP strained multiquantum-well buried-heterostructure lasers

Stripe-width and cavity length dependencies of high-temperature performances of 1.3-/spl mu/m InGaAsP-InP well-designed buried-heterostructure strained multiquantum-well (MQW) lasers were investigated. The threshold currents as low as 4.5/10.5 mA and slope efficiencies as high as 0.48/0.42 mW/mA at 25/spl deg/C/85/spl deg/C were obtained in the MQW lasers with 1.5-/spl mu/m width, 250-/spl mu/m length, and 0.3/0.85 facet reflectivity. With temperature increasing from 25/spl deg/C to 85/spl deg/C, the MQW lasers exhibited lower output power degradation, the minimum value was 1.78 dB at an operation current of 45 mA. The MQW lasers were suitable for application in optical access networks.     

High extinction ratio and high-temperature 2.5-Gb/s floor-free 1.3-/spl mu/m transmission with a directly modulated quantum dot laser

For the first time with a directly modulated InAs-GaAs quantum-dot laser, high extinction ratio (up to 17 dB) and 25/spl deg/C-85/spl deg/C single-mode-fiber data floor-free transmissions are achieved at 2.5 Gb/s. Moreover, an interferometric technique showed a nearly constant Henry factor /spl sim/2 until a bias current six times the threshold current.     

Efficient CW lasing and high-speed Modulation of 1.3-/spl mu/m AlGaInAs VCSELs with good high temperature lasing performance

The 1.31-/spl mu/m AlGaInAs vertical-cavity surface-emitting lasers achieved efficient single-mode (SM) continuous-wave lasing at temperatures up to 120/spl deg/C, with 2.0-mW output power and 31% slope efficiency, as well as multimode (MM) lasing with up to 9-mW output power and up to 39% slope efficiency. High-speed modulation at data rates up to 10 Gb/s and transmission through different lengths of SM and MM fiber are demonstrated.     

160/spl deg/C pulsed laser operation of AlGaInP-based vertical-cavity surface-emitting lasers

Pulsed lasing operation of a 670 nm AlGaInP-based oxide-confined vertical-cavity surface-emitting laser (VCSEL) at high temperatures is demonstrated. At +120/spl deg/C heatsink temperature output power exceeded 0.5 mW and at +160/spl deg/C 25 /spl mu/W output power was achieved     

All-epitaxial InAlGaAs-InP VCSELs in the 1.3-1.6-/spl mu/m wavelength range for CWDM band applications

All-epitaxial InAlGaAs-InP vertical-cavity surface-emitting lasers grown by metal-organic chemical vapor deposition were successfully demonstrated in the wavelength ranging from 1.3 to 1.6 /spl mu/m. The devices showed the high performances such as single-mode output power of higher than 1.1mW, sidemode suppression ratio of 37 dB, divergence angle of 9/spl deg/, and CW operation of temperature up to 80 /spl deg/C. We achieved the modulation bandwidth exceeding 2.5 Gb/s and power penalty free transmission over 30 km.