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We describe the design, fabrication, and performance of a five-element quarterwave-shifted distributed feedback laser array with monolithically integrated spot size converters intended for use as a multiple-wavelength source in dense wavelength-division telecommunications systems. Facet power in excess of 10 mW with less than 150 mA bias and longitudinal side mode suppression greater than 40 dB were routinely achieved. Narrow far-field full-width at half-maximum angles of 6.9/spl deg//spl times/16.3/spl deg/ provided 3.5-dB coupling loss into single-mode fiber with 1.0-dB misalignment tolerances of /spl plusmn/2.0 /spl mu/m. With /spl plusmn/10/spl deg/C thermal tuning, 22 1555-nm channels spaced by 50 GHz were accessed with this device. Thorough field evaluation indicates that such a device is consistent with manufacturing requirements.

We have demonstrated a semiconductor optical amplifier and electroabsorption modulator monolithically integrated with a novel dual-waveguide spot-size converter at the input for low-loss coupling to planar lightguide circuit silica waveguides or cleaved single-mode optical fiber. These devices exhibit greater than 10 dB fiber-to-fiber gain, output power of +4 dBm, 3-dB modulation bandwidth of 6 GHz, and modulator extinction ratios of 20 dB dc and 14.4 dB RF for a 2.4-V/sub pp/ drive.

We describe a 4 by 4 array of embedded control two input, one output optoelectronic switching nodes based on the field effect transistor self electro-optic effect device (FET-SEED) technology. The arrays have electrical fan-out to remove the loss associated with optical fan-out in the system application. Extensive testing was done on several arrays at 156 Mb/s per channel with optical switching energies below 100 fJ, with the output driver limiting the maximum data rate to 400 Mb/s. Power dissipation, noise margin, crosstalk, sensitivity to stray light, and uniformity of both threshold and output waveforms are also discussed. >

We present the design, fabrication, and demonstration of a 10/spl times/10 matrix-addressed vertical-cavity top-surface-emitting laser (VCSEL) array. These arrays are batch-fabricated from full 3-in diameter GaAs/AlGaAs wafers. We show that no performance-penalty is paid using top-contacted matrix addressed pixels over conventional planar VCSEL devices. A computer-controlled display system for electrically addressing the array was designed and constructed to permit video demonstration and array testing. >

In this letter, we have developed a tandem electroabsorption modulator with an integrated semiconductor optical amplifier that is capable of both nonreturn-to-zero and return-to-zero (RZ) data transmission at 40 Gb/s. The tandem modulator consists of a broad-band data encoder and a narrow-band pulse carver. The pulse carver is able to produce 5-ps pulses with more than 20 dB of extinction. The on-chip semiconductor optical amplifier provides up to 8.5 dB of fiber-to-fiber gain and enables the modulator to be operated with zero insertion loss. Devices have been realized with greater than 40-GHz bandwidth, and 13-dB dynamic extinction for a 2.5-V swing. For optimized designs bandwidths of nearly 60 GHz: have been realized. Using these devices penalty free RZ data transmission over a 100-kin dispersion compensated fiber link has been demonstrated with a received power sensitivity of -29 dBm.

The structure, processing, and performance of arrays of integrated field-effect transistor-self-electrooptic effects devices (FET-SEEDs) consisting of doped-channel field-effect transistors, multiple quantum-well (MQW) modulators, and p-i-n MQW detectors are discussed. The performance of the FETs and SEEDs such as g/sub m/ and contrast, is equivalent to that obtained when they are made separately. Typical values are g/sub m/=80 mS/mm and contrast of 3. The largest arrays contain 128 circuits. The circuits operate at speeds as fast as 500 Mb/s, with optical input switching energy of approximately=400 fJ. At 170 Mb/s, the required optical input switching energy is approximately=70 fJ. This optical energy is at least a factor of 20 less than for symmetric SEEDs (S-SEEDs) with the same optical window sizes. Hence, FET-SEEDs provide superior performance compared to conventional S-SEEDs. >

Two-dimensional arrays of logic self-electrooptic effect devices (L-SEEDs), consisting of electrically connected quantum-well p-i-n diode detectors and modulators are demonstrated. The topology of the electrical connections between the detectors is equivalent to the connections between transistors in CMOS circuits. Three different L-SEED arrays were built and tested. Each element in one array can implement any of the four basic Boolean logic functions (i.e., NOR, NAND, AND, OR). Each element in the second L-SEED array can implement the function E=AB+CD. The third L-SEED array consists of 32*16 arrays of symmetric SEEDs (S-SEEDs) connected with optoelectronic transmission gates. Photonic switching nodes, multiplexers, demultiplexers, and shift registers have been demonstrated using this array. >

We report on the design, fabrication and characterization of a novel 40 Gb/s optical receiver. The device consists of a high-speed waveguide photodiode monolithically integrated with a semiconductor optical amplifier to create a fully photonic receiver. We have achieved a back-to-back receiver sensitivity of -17 dBm for NRZ data transmission at 40 Gb/s. When used with an erbium doped fiber preamplifier a sensitivity of -32 dBm or 123 photons/bit has been realized for RZ transmission with -6 dBm input power at the receiver. The device has a small signal bandwidth of 39 GHz and a conversion gain of more than 800 Volts per Watt.

NRZ and RZ data transmission at 40 Gb/s are demonstrated for the first time using buried heterostructure tandem electro-absorption modulators monolithically integrated with a semiconductor optical amplifier and input/output spot-size converters. Zero penalty RZ transmission over a 100 km dispersion managed link is achieved.

Wavelength selectable semiconductor lasers serve as tunable light sources in wavelength division multiplexed telecommunication systems. We report on 2.5 and 10 Gb/s electro-absorption modulated wavelength selectable laser modules based on highly reliable, closed-loop controlled, five-section InP wavelength selectable lasers.

We have demonstrated simultaneous demultiplexing and clock recovery of 80 Gb/s OTDM signals for the first time. With 3 V/sub PP/ drive voltage at 20 GHz on the first EAM and at 10 GHz on the second EAM, the switching window of the tandem EAM is 9 ps. The penalty for an 80 Gb/s OTDM signal demultiplexed to 10 Gb/s is 1.2 dB compared to a 20 Gb/s signal demultiplexed to 10 Gb/s. This configuration makes the demultiplexing receiver very compact and simple.

A wavelength selectable source within a transmitter for high-speed, dense wavelength division multiplexed systems must tune across a substantial number of channels while meeting rigorous system specifications in each channel. It must offer the same level of stability, reliability and ease of use as single wavelength counterparts. We examine a tunable source designed to meet the needs of high bit-rate DWDM systems for long-haul and metro applications.

We demonstrate for the first time a 10 Gb/s EA-modulated wavelength-selectable DBR laser module with an integrated semiconductor optical amplifier. Transmission over 82 km of standard fiber with -3 dBm average power on 20 channels spaced by 50 GHz is achieved.

A wavelength selectable transmitter for 2.5 or 10 Gb/s dense wavelength division multiplexed (DWDM) systems must tune across a substantial number of channels while meeting rigorous system specifications in each channel. Moreover, a tunable transmitter must feature the same level of stability, reliability and ease of use compared to single wavelength counterparts. We examine a 20-channel transmitter designed to meet the needs of high bit-rate DWDM systems.

Fabry-Perot and distributed feedback spot size converted 1.3 /spl mu/m lasers are demonstrated with competitive performance (/spl sim/10 mA threshold, >0.30 W/A slope) and narrow (16/spl times/9) far fields capable of coupling 45% of the output light into flat cleaved fiber. The Fabry-Perot device demonstrated error-floor-free transmission at 85/spl deg/C with a wide-open eye, uncooled 2.5 Gb/s operation up to 85/spl deg/C, and reliability of 105 FITS at 50/spl deg/C. The DFB devices have good DC performance with side mode suppression ratios of >40 dB. These devices will allow passive alignment and packaging without the need for intervening optics.

Wavelength-selectable lasers are key enablers for future all-optical networks. We report on fully functional 2.5 and 10 Gb/s EA-modulated wavelength-selectable laser modules based on a highly integrated InP chip that are suitable for high-reliability telecom applications.

NRZ and RZ data transmission at 40Gb/s are demonstrated for the first time using buried heterostructure tandem electro-absorption modulators monolithically integrated with a semiconductor optical amplifier and input/output spot-size converters. Zero penalty RZ transmission over a 100km dispersion managed link is achieved.

We have used an electrical technique to determine the ambipolar lifetime in p‐i‐n GaAs/AlGaAs self‐electro‐optic‐effect devices in which the i region consists of a multiple quantum well structure (MQW). From an analysis of the voltage drop in the i region obtained from the forward current‐voltage characteristics, values for the ambipolar lifetimes are derived for diodes with different MQW. A value of 80–90 ps is determined for the ambipolar lifetime which is found not to change significantly when the AlxGa1−xAs barrier thickness or composition is reduced from 65 to 35 A or x∼0.3 to 0.2, respectively, in the MQW. Since these changes in the barrier have previously been shown to improve photoresponse efficiency of the p‐i‐n diode, it is inferred that the carrier escape and collection times are smaller than 80–90 ps in devices with thin (35 A) or low (x∼0.2) AlxGa1−xAs barrier.

We describe symmetric self‐electro‐optic effect devices (S‐SEEDs) with clamping diodes connected to the center node of the devices to ensure both diodes of the S‐SEEDs have an electric field across them at all times. These diode‐clamped S‐SEEDs operate over a greater wavelength range, with greater powers before saturating, and have lower optical switching energies compared to conventional S‐SEEDs. An 8×8 array of diode‐clamped S‐SEEDs has been built and tested. We have demonstrated bistable operation with voltage swings of only 2 V over a wavelength range of 15 nm. Required optical switching energies of 340–580 fJ were measured at input powers from 500 nW to 100 μW for devices with 10×10 μm mesas. This is the lowest reported switching energy for any SEED with acceptable bistable characteristics.

We report measurements of excess wavelength chirp caused by high frequency electrical crosstalk between an electroabsorption modulator and the tuning section of a monolithically integrated DBR laser. The high tuning efficiency of the laser leads to stringent electrical isolation requirements.

In order to meet the increasing market needs for uncooled lasers for such applications as fiber- in-the-loop, high efficiency, high power, and highly reliable 1.3 micrometer uncooled InGaAsP/InP strained multi-quantum well Fabry-Perot lasers were fabricated with 50 mm wafer processing. Slope efficiency as high as 0.39 W/A and peak power as high as 46 mW at 85 degrees Celsius was obtained by optimizing the device structure for high temperature operation. We have also demonstrated excellent uniformity and reproducibility over 6 wafers. Reliability was also shown to be very good. More than 10,000 chips sites are available on a 50 mm wafer, and the cost is expected to be low. Because of the high performance, these lasers are expected to be used for various applications.

The complexity and size of interconnection-rich telephone switching systems require the extension of data buses over a large complement of frames. Physical designers have chosen bit serial transport over fiber to overcome the length limitations of coaxial cable from attenuation, to reduce cable volume, to provide isolation and avoid ground loops, to reduce RFI and EMI interference and coupling between channels, and to be able to make and break live connections without damaging the transmitter or receiver electronics. It has been shown that for certain interconnection applications there exists an optimum degree of parallelism (based on cost), depending on the data rate and the number of the channels.1 Prototype one-dimensional optical data links (1D-ODL’s) using linear 1 × n device arrays have been demonstrated in a number of laboratories and take advantage of the current infrastructure of fiber ribbon, splices, and connectors. Extending this concept to a second dimension by creating a two-dimensional optical data link (2D-ODL) using n×m device arrays may yield further economies of scale. We have constructed several prototype 2D-ODL’s (Table 1 ) using direct modulation of 2D arrays of vertical-cavity surface-emitting lasers (VCSEL’s)2 as shown in Fig. 1, and symmetric self-electro-optic effect device (S-SEED) modulators3 with Si P-I-N/bipolar OEIC receivers.4 The benefits and drawbacks of each technology will be briefly discussed.

The self-electro-optic effect device (SEED) and the symmetric SEED (S-SEED) have demonstrated considerable applications for photonic switching and logic functionality. A SEED consists of a p-i-n, mesa diode, with a multiple-quantum-well structure for the i region. The symmetric SEED consists of two p-i-n mesa diodes connected in series. The S-SEED has been fabricated in functional arrays containing as many as 32×64 elements. The SEED and S-SEED are operated under a reverse bias, thus low reverse leakage is desired. As the magnitude of the reverse leakage current increases, more incident laser power is required to switch device states and then hold that state. Therefore, understanding the origins of the reverse leakage current and its dependence on mesa and array size is imperative for optimizing device performance.

The forward current-voltage (I-V) characteristics of GaAs/AlGaAs Self Electro-optic Effect Device (SEED) p-i-n diodes were measured. The I-V curves exhibited a diode like behavior with an ideality factor of 2 for voltages in the range 0.5–1.25V. In this region, the diode series resistance varied inverse proportional to the forward current with the constant of proportionality being equal to this voltage drop in the i-region. From an analysis of the experimentally obtained voltage drop, the ambipolar lifetime was determined. For the standard device whose i-region had a multi quantum well structure consisting of 60 periods of 100Å undoped GaAs wells and 65Å undoped Al0.30Ga0.70 As barriers, the ambipolar lifetime was found to be 79.6±3 psec for a 30×30 μm2 mesa device and 92 ± 4 psec for a 100×100 μm2 mesa device. When the barrier width was reduced to 35Å or when the barrier Al composition decreased to 0.2, no significant change in the ambipolar lifetime was measured. Since previous measurements have indicated that decreasing the barrier width or height greatly enhances carrier escape from the wells during the operation of the GaAs/AlGaAs p-i-n diode as a photodetector, it is inferred that the carrier escape and collection times are smaller than ∼ 80–90 psec.

Arrays of Symmetric Self Electro-optic Effect Devices can function in multi-stage digital optics systems at higher data rates with less external optical power than previously predicted.

A novel 40 Gbit/s optical receiver is presented. The device consists of a waveguide photodiode integrated with a semiconductor optical amplifier. The receiver has a small signal bandwidth of 39 GHz and a conversion gain of more than 800 V/W. A back-to-back sensitivity of -17 dBm has been demonstrated for non-return to zero data transmission at 40 Gbit/s. A sensitivity of -32dBm or 110 photons/bit has been realised for 40 Gbit/s return to zero transmission with an erbium doped fibre preamplifier and an optical filter.

We describe a 6 × 6 array of electrically addressed field-effect-transistor self-electro-optic-effect-device differential modulators in which each element has a single-stage amplifier to permit an input voltage of less than 1 V to control the output modulators, which can operate at as high as 10 V. The variations in the switching voltages across the array are less than ±70 mV, and the individual array elements are operated at as high as 2 Gbits/s. We also measure cross talk between adjacent elements within the array, measure the dependence of the switching time on the input voltage swing, and calculate the dependence of the switching time that is due to the photocurrent of the modulators.