High brightness visible (660 nm) resonant-cavity light-emittingdiode

Visible (660 nm) resonant-cavity light-emitting (RCLEDs) have been fabricated. The top-emitting devices employed two AlGaAs-AlAs-Bragg mirrors and GaInP-AlGaInP quantum-well active layers. The device performance was characterized as a function of the device diameters, ranging from 24 to 202 μm. The larger devices exhibited a nearly linear increase of output power with injected current with 8.4-mW emission at 120 mA. A maximum external efficiency of 4.8% was measured at 4 mA on the 84-μm aperture devices. All devices exhibited a narrow emission at 659-661 nm with a linewidth around 3 nm. The results show that RCLED's are promising low-cost light sources for plastic fiber transmission as well as display applications     

High-power broad-band superluminescent diode with low spectralmodulation at 1.5-μm wavelength

A 1.5-μm wavelength superluminescent light source operating at a heat sink temperature of 13°C with the following properties was realized: 20-mW continuous wave output power, 130-nm spectral bandwidth, and 0.2-dB spectral modulation. This light source consists of an angled facet single-mode waveguide with a rear absorption region. These results were obtained by optimizing the epitaxial design, the waveguide design, and the device mounting     

Ten-to-twenty gigabit-per-second modulation performance of1.5-μm distributed feedback lasers for frequency-shift-keying systems

The frequency modulation (FM) and amplitude modulation (AM) responses of a 1.5-μm distributed feedback (DFB) laser were measured to 15 GHz. At 9-mW output power, the magnitude of the FM response was flat out to 12 GHz, and there was a 15-25-ps delay between the FM and AM responses. Computer simulation techniques indicate that the measured FM response is adequate to produce good eye patterns for frequency-shift-keying modulation at data rates up to 20 Gb/s. The high-speed frequency-shift-keying modulation capability of this 1.5-μm DFB laser was experimentally confirmed at 11 Gb/s     

Optical amplification in Er3+-doped single-mode fluoridefiber

The amplification characteristics at around 1.5 μm of a 0.9-m-long, 1000-p.p.m Er³⁺-doped single-mode fluoride fiber are discussed. By using 1.48-μm laser diodes with 55-mW launched output as a pump source, a gain of 1.75 dB was obtained at 1.530 μm. A broad bandwidth of 40 nm was obtained, which may be suitable for wavelength-division multiplexing (WDM) system use     

Integration of high-Q GaAs varactor diodes and 0.25 μmGaAs MESFET's for multifunction millimeter-wave monolithic circuitapplications

Two technologies are demonstrated whereby high-Q, vertical-structure, abrupt-junction varactor diodes are monolithically integrated with 0.25-μm GaAs MESFETs on semi-insulating GaAs substrates for multifunction millimeter-wave monolithic circuit applications. Diodes with various anode sizes have been realized with measured capacitance swings of >2.1:1 from 0 V to -4 V and series resistances of approximately 1 Ω. Diodes having a zero bias capacitance of 0.35 pF have Q's of >19000 (50 MHz) with -4 V applied to the anode. Under power bias conditions, the MESFETs have a measured gain of >6 dB at 35 GHz with extrapolated values for f _t and f_max of 32 GHz and 78 GHz, respectively. Using these technologies, a monolithic Ka-band voltage controlled oscillator (VCO) containing a varactor diode, a 0.25-μm GaAs MESFET, and the usual MMIC passive components has been built and tested. At around 31 GHz, the circuit has demonstrated 60-mW power output with 300 MHz of tuning bandwidth     

Dynamic characteristics of high speed p-substrate GaInAsP buriedcrescent lasers

A detailed behavior of 1.3-μm GaInAsP p-substrate buried-crescent lasers emitting maximum output powers of more than 30 mW/facet is discussed. A 3-dB modulation bandwidth of 11.5 GHz, and relative intensity noise level of ~-145 dB/Hz were observed at 5 I _th. The two-tone intermodulation distortion was more than 30 dB below the 9-GHz subcarriers for a current modulation index of ~40%     

High-power single-mode simplified antiresonant reflecting opticalwaveguide (S-ARROW) distributed feedback semiconductor lasers

Simplified antiresonant-reflective-optical-waveguide distributed-feedback semiconductor lasers based on Al-free InGaAs-InGaAsP-InGaP materials are reported for the first time. Devices with 6.5-μm-wide emitting apertures operate single-frequency (λ=0.968 μm) and single-spatial-mode to 157-mW continuous-wave output power. The full-width at half-maximum of the lateral far-field pattern is 4.5°, in excellent agreement with theory. Relative intensity noise values as low as -154 dB/Hz are measured between 500 MHz and 8 GHz     

High-gain W band pseudomorphic InGaAs power HEMTs

The authors have fabricated 0.1-μm T-gate pseudomorphic (PM) InGaAs power high-electron-mobility transistors (HEMTs) with record power and gain performance at 94 GHz. Devices with 40-μm gate peripheries achieved 10.6-mW output power with 7.3-dB gain and 14.3% power-added efficiency (PAE). Devices with 160-μm gate peripheries achieved 62.7-mW output power with 4.0-dB gain and 13.2% PAE. The authors believe the superior performance of these devices is due to the combination of a short 0.1-μm T-gate, high-quality material, optimized device profile, and the reduction in source inductance due to source vias     

High-performance large-area InGaAs metal-semiconductor-metalphotodetectors

The fabrication and characteristics of high-performance large-area InP:Fe/InGaAs:Fe/InP:Fe metal-semiconductor-metal (MSM) photodetectors are reported. With a 350-μm×350-μm active area, the detectors offer 900-MHz electrical bandwidth and 1.7-pF capacitance at 10-V bias. The respective dark current density is 20 pA/μm², an the CW responsivity is 0.4 A/W at 1.3-μm wavelength. The detectors are therefore ideally suited for applications in the long-wavelength range that require a large detection area and, at the same time, a high bandwidth and low capacitance     

High-power, broad-band 1550 nm light source by tandem combinationof a superluminescent diode and an Er-doped fiber amplifier

A high-power (20-mW) broadband (21-nm-FWHM) 1.55-μm light source with small spectral modulation depth has been achieved by amplifying the output of a superluminescent diode (SLD) with an Er-doped fiber amplifier (EDFA). These characteristics are desirable for fiber gyroscope applications. The twin fluorescence peak problem is solved by operating the EDFA in the saturated region with an injected SLD signal     

Observation of nonbiased degradation recovery in GaInAsP/InP laserdiodes

Conventional accelerated lifetests of laser diodes generally involve operating the devices continuously at either constant drive current or power output with periodic recording of their characteristics. In this work, a new observation of degradation recovery from a noncontinuous lifetest performed on 1.3-μm GaInAsP/InP double-heterostructure (DH) laser diodes of the inverted-rib structure is reported. This nonconventional lifetest method involves constant 5-mW/facet biasing at 50°C followed by a period of no bias at room temperature. On average, the threshold current and current for 5-mW/facet output reduced by 6.7 and 8.4%, respectively, during the unbiased period. Redistribution of mobile defects in the cladding layer is postulated to be the mechanism responsible for the degradation recovery     

Linear 0.20 GHz modulation with a 1×2 directional coupler

The design and performance of a traveling-wave 1×2 directional coupler modulator are described. A 0-20 GHz response (-4 dB _e) was achieved for Ti:LiNbO₃ devices at the 1.3-μm wavelength. From experimental determinations of coupling coefficient and interarm intrinsic phase-mismatch for several modulators, linear dynamic ranges of, on average, 78 dB and voltage sensitivities of down to 9 μV are determined (for 1-mW detector power, 3-kHz bandwidth, 50-Ω detector load). The dependence of sensitivity on the coupling coefficient is described, and the effect of the buffer layer thickness on the optical bandwidth and sensitivity is demonstrated     

3-V MSM-TIA for Gigabit Ethernet

The paper describes a 3-V monolithically integrated metal-semiconductor-metal photodetector (MSM-PD) and transimpedance amplifier (TIA) chip that is fully compliant with the Gigabit Ethernet receiver specification for the short-reach application (IEEE 802.3z 1000BASE-SX). Key typical performance specifications are -22 dBm sensitivity, 1200 MHz 3-dB bandwidth, 1300-V/W differential responsivity, and 120-mW power dissipation at 3 V. The chip is fabricated in a production 0.5-μm gate length GaAs MESFET technology and is packaged in a TO-46 header with a flat window and a ball-lens cap option     

1.57 μm strained-layer quantum-well GaInAlAs ridge-waveguidelaser diodes with high temperature (130°C) and ultrahigh-speed (17GHz) performance

The fabrication of GaInAlAs strained-layer (SL) multiple-quantum-well (MQW) ridge-waveguide (RW) laser diodes emitting at 1.57 μm is discussed. Due to an optimized layer structure, a very high characteristic temperature of 90 K was obtained. As a consequence for episide-up mounted devices, the maximum continuous wave (CW)-operation temperature is 130°C. At room temperature, a maximum output power of 47 mW was measured for 600-μm-long lasers with one high-reflection coated facet. The low series resistance of 4 Ω (2 Ω) for 200-μm-(400-μm)-long devices yields an ultrahigh 3-dB bandwidth of 17 GHz. These static and dynamic properties also result from a high internal quantum-efficiency of 0.83 and a high differential gain of 5.5×10^-15 cm²     

Design and implementation of high-speed planar Si photodiodesfabricated on SOI substrates

We report high-speed interdigitated (nonmetalized) p-i-n Si photodiodes fabricated on SOI substrates that operate at low bias voltages and that offer easy integration with transistor fabrication processes. Devices fabricated with a finger spacing of 2 μm and a 3.75-μm-thick active layer achieved a 1.1-GHz bandwidth at a bias of -3 V with a peak efficiency of 29% (0.2 A/W) at 850 nm. Photodiodes with the same geometry that were fabricated on a 2.71-μm-thick active layer exhibited a 3.4-GHz bandwidth and a quantum efficiency of 24% (0.16 A/W) at 840 nm when biased at -3 V. The dark current of the photodiodes was less than 25 pA at -3 V, and the capacitance of the photodiodes was less than 265 fF at an applied bias of -3 V     

Single transverse mode operation of 1.55-μm buriedheterostructure vertical-cavity surface-emitting lasers

In this letter, we report the single-mode operation of 1.55-μm buried heterostructure vertical-cavity surface-emitting lasers (VCSELs) fabricated on a GaAs-AlAs distributed Bragg reflector using thin-film wafer fusion. A 7-μm VCSEL exhibits a single transverse mode at up to about 0.1-mW maximum optical output power and 75°C maximum operation temperature under continuous-wave operation     

Performance of telecommunication-grade multimode fiber at 780 nm

Presents the physics of graded-index multimode fiber and test results that demonstrate 780-nm compact disc (CD) lasers operating at the high speeds (266 Mb/s) and moderate distances (~2 km) for data communications. The test results include fiber characterizations of bandwidth and attenuation, and system performance testing of bit error rate measurements and eye closure characterization. The predictability of 780-nm performance from existing characterization at the traditional wavelengths of 850 and 1300 nm is sufficiently precise to permit the conservativeness necessary for standardization. Telecommunication-grade 50-μm fiber is ideally suited to this application because commercial pressures have caused 62.5-μm fiber to be optimized for 1300-nm light emitting diode (LED) operation     

Extremely low threshold current operation in 1.5-μm MQW-DFBlaser diodes with semi-insulating InP current blocking region

Threshold current operation of 1.5 mA was achieved for 1.5-μm multiple-quantum-well distributed feedback (MQW-DFB) laser diodes (LDs) with semi-insulating current blocking layers entirely grown by metalorganic vapor phase epitaxy (MOVPE). Such low-threshold current is attained by reducing leakage current and mirror loss in the laser structure. The required bias current for achieving several gigahertz bandwidth is markedly reduced due to the enhanced differential gain and low threshold current. Due to the reduced lasing delay time in such low threshold LDs, up to 5-GHz zero-bias current modulation, with a clear eye opening, is successfully demonstrated     

High-speed modulation characteristics of helium-implantedzinc-diffused vertical cavity surface emitting lasers

The high-speed modulation characteristics of helium-implanted zinc-diffused vertical cavity surface emitting semiconductor lasers are measured. Devices with a nominal active region diameter of 10 and 20 μm exhibit a move-out rate of 4.5-6.5 GHz/mW^1/2 and a K factor of 0.65-0.85 ns. Maximum modulation frequency is limited by ohmic heating to approximately 5.5 GHz for 10-μm diameter lasers and to 2.7 GHz for 20-μm diameter lasers. A rolloff in the response below the relaxation oscillation frequency is observed and is explained well by a diffusion capacitance model     

Temperature dependence of dynamic and DC characteristics ofquantum-well and quantum-dot lasers: a comparative study

Dynamic and static characteristics of high-speed 1.55- and 1-μm wavelength tunneling injection quantum-well lasers and 1-μm wavelength self-organized quantum-dot lasers, have been measured as a function of temperature. While differential gain of the quantum-well lasers greatly increased with lowering of temperature (by a factor of 50), gain compression increased along with it, resulting in about the same intrinsic damping limit (K-factor) over a wide range of temperatures and only moderate increases in bandwidth (20-35 GHz). This suggests that increase in differential gain alone is not sufficient to improve modulation characteristics directly. Because of the mechanism of gain compression, lasers which are damping limited may not see a large improvement in modulation bandwidth simply by operating at lower temperature. In contrast, the modulation bandwidth of the quantum-dot lasers increased from 5-6 GHz at room temperature to larger than 20 GHz at 90 K. This behavior is explained by considering electron-hole scattering as the dominant mechanism-for electron capture in quantum-dots. The measured temperature dependence of the K-factor is analyzed with consideration of electron-hole scattering, and the value extracted for the electron intersubband spacing from this analysis, 60 meV, agrees with the theoretically calculated value of 56 meV