High-temperature characteristics of 1.3-μm InAsP-InAlGaAs ridgewaveguide lasers

High-temperature characteristics of InAsP-InAlGaAs strained multiquantum-well (MQW) lasers with a large conduction band discontinuity (ΔE_c) are demonstrated. The InAsP-InAlGaAs MQW ridge waveguide lasers with narrow stripes exhibited a characteristic temperature as high as 143 K in the range from 25°C to 85°C. This material system is promising for developing a cooling-system-free 1.3-μm laser     

Power stabilisation of uncooled 980 nm pump laser modules from 10to 100°C

Efficient fibre Bragg grating wavelength and power stabilisation of 980 nm pump lasers at high fibre-coupled output power (250 mW at 10°C and 95 mW at 100°C) over a wide temperature range of 90°C is demonstrated     

200°C, 96-nm wavelength range, continuous-wave lasing fromunbonded GaAs MOVPE-grown vertical cavity surface-emitting lasers

We report record temperature and wavelength range attained using MOVPE-grown AlGaAs vertical cavity surface-emitting lasers (VCSEL's). Unbonded continuous-wave lasing is achieved at temperatures up to 200°C from these top-emitting VCSEL's and operation over a 96-nm wavelength regime near 850 nm is also achieved from the same nominal design. Temperature and wavelength insensitive operation is also demonstrated; threshold current is controlled to within a factor of 2 (2.5-5 mA) for a wavelength range exceeding 50 nm and to within ±30% (5-10 mA) for a temperature range of 190°C at 870 nm     

25 to 300°C ultra-low-power voltage reference compatible withstandard SOI CMOS process

A new patented voltage reference is presented. The very simple architecture, which can be implemented in standard silicon-on-insulator CMOS processes, gives very low power consumption (from 1 pA at 25°C up to 50 nA at 300°C) and good voltage stability (about 200 ppm/°C) over the whole temperature range     

High performance and high reliability of 1.55-μmcurrent-blocking grating complex-coupled DFB lasers

We report the high performance and high reliability of the 1.55 μm current-blocking grating complex-coupled InGaAsP strained distributed-feedback MQW lasers. Small variation in slope efficiency, high characteristic temperature, and high side mode suppression ratio have been achieved over a wide temperature range of 20°C-90°C. From the accelerated aging test, the median life at 25°C and 5 mW is estimated to be longer than 50 years     

Low dispersion penalty and wide temperature range operation over120 K with 1.55 μm strained MQW-DFB laser module

STM 16 (2.488 Gbit/s) system operation over a wide DFB chip temperature range of more than 120 K (from -25°C to +95°C) is presented with dispersion penalty below 1 dB after transmission across 100 km standard fibre. DFB operation at 1.55 μm with a high sidemode suppression ratio of 40 dB is achieved within -40°C to +95°C. The lasers were realised using a BRS lateral structure and a quaternary InGaAsP MQW stack with six compressively strained quantum wells and a highly detuned DFB grating     

High-coupling-efficient 1.3-μm laser diodes with goodtemperature characteristics

We have proposed uniformly beam-expanded structures based on the advanced concept for realizing high coupling efficiency and good temperature characteristics. Beam expansion (optical confinement reduction) by narrowing the core layer width as well as a carrier confinement are strongly enhanced by adopting a larger bandgap InGaAsP for MQW barriers and separate confinement heterostructure layers. These laser diodes (LD's) were fabricated by the conventional buried heterostructure laser process, which is very important in reducing the cost. Our results have proven the effectiveness of our proposition. The LD's with high coupling efficiency (-3.2 dB) and good temperature characteristics have been achieved even using the simple approach of reducing optical confinement. The threshold currents at 25 and 85°C are 9.3 and 39.4 mA, respectively. The slope efficiency at 25°C is 0.39 W/A and still high (0.26 W/A) even at 85°C     

On the operational and manufacturing tolerances of GaAs-AlAs MQWmodulators

We approach the question of optimization of surface-normal p-i(multiquantum-well, MQW)-n modulators from the viewpoint of investigating their tolerance to variations in wavelength and temperature and errors in manufacture. The reflection characteristics of two high-quality samples are carefully processed to eliminate Fabry-Perot fringes, and then their spectra at any bias are characterized with six phenomenological parameters which depend on λ₀, the zero-field exciton position. The two GaAs-AlAs samples have λ₀'s of 833.8 and 842.3 nm, and so cover a range useful for modulators designed to operate near 850 nm in the normally reflecting condition, i.e., reflection decreases with field. A linear interpolation of the parameters of these two samples is used to predict the behavior of MQW diodes with λ₀'s around this range, and so a fully comprehensive examination of normally reflecting MQW modulators is performed. The performance aspect that is examined is contrast ratio as a function of nonuniformities in the devices or operating conditions given a voltage swing of 3 V. There are two operational modes discussed. If the voltage offset of the bias is allowed to vary via a feedback circuit, a contrast of 2:1 may be maintained over an operating wavelength change (Δλ) of 17 nm with local variations of wavelength of ±1 nm, which corresponds to a temperature variation of 60°C while allowing for variations of laser driver wavelength of ±1 nm. If feedback Is not permitted, we determine that, given tolerances to manufacturing errors, a contrast of 1.5:1 may be maintained over a wavelength range of ~5 nm by either using stacked diode designs or extremely shallow quantum wells     

High-performance λ=1.3 μm InGaAsP-InP strained-layerquantum well lasers

Compressively and tensile strained InGaAsP-InP MQW Fabry-Perot and distributed feedback lasers emitting at 1.3-μm wavelength are reported. For both signs of the strain, improved device performance over bulk InGaAsP and lattice-matched InGaAsP-InP MQW lasers was observed. Tensile strained MQW lasers show TM polarized emission, and with one facet high reflectivity (HR) coated the threshold currents are 6.4 and 12 mA at 20 and 60°C, respectively. At 100°C, over 20-mW output power is obtained from 250-μm-cavity length lasers, and HR-coated lasers show minimum thresholds as low as 6.8 mA. Compressively strained InGaAsP-InP MQW lasers show improved differential efficiencies, CW threshold currents as low as 1.3 and 2.5 mA for HR-coated single- and multiple quantum well active layers, respectively, and record CW output powers as high as 380 mW for HR-AR coated devices. For both signs of the strain, strain-compensation applied by oppositely strained barrier and separate confinement layers, results in higher intensity, narrower-linewidth photoluminescence emissions, and reduced threshold currents. Furthermore, the strain compensation is shown to be effective for improving the reliability of strained MQW structures with the quantum wells grown near the critical thickness. Linewidth enhancement factors as low as 2 at the lasing wavelength were measured for both types of strain. Distributed feedback lasers employing either compressively or tensile strained InGaAsP-InP MQW active layers both emit single-mode output powers of over 80 mW and show narrow linewidths of 500 kHz     

Temperature-dependent characteristics of 1.3-μm AlGaInAs-InPlasers with multiquantum barriers at the guiding layers

Strain-compensated 1.3-μm AlGaInAs-InP multiquantum-well (MQW) lasers with multiquantum barriers at both the n- and p-type guiding layers are comprehensively studied. The laser exhibits a characteristic temperature as high as 95 K and degradation in slope efficiency as low as -1.06 dB in the temperature range from 25°C to 75°C. The characteristic temperature of transparency current density is deduced to be 129 K. It is also found that the internal loss increases slowly with temperature, while the temperature dependence of the internal quantum efficiency dominates the degradation of the external quantum efficiency due to the degradation of the stimulated recombination, and significant increase of electron and hole leakage at high temperature     

A 300°C dynamic-feedback instrumentation amplifier

A high-temperature instrumentation amplifier that uses dynamic feedback is presented. It realizes dynamic feedback by means of a rotating chain of resistors to compensate for resistor mismatches. An 11× dynamic-feedback instrumentation amplifier has been integrated in a standard junction-isolated 1.6-μm CMOS process and realizes an average gain error below 25 ppm up to 250°C without calibration or trimming. Leakage currents cause additional gain errors at higher temperatures. Nevertheless, even at 300°C, this average gain error is still less than 500 ppm     

High-temperature single-mode operation of 1.3-μm strained MQWgain-coupled DFB lasers

Single-mode and high-power operation at temperatures up to 120°C has been achieved in 1.3-μm strained MQW gain-coupled DFB lasers. A stable lasing wavelength is maintained due to a large modal facet loss difference of the two Bragg modes, which is provided by the gain-coupling effect. A very low temperature dependence of the threshold current has been obtained by detuning the lasing wavelength to the long wavelength side of the material gain peak at room temperature, which effectively compensates the waveguide loss at higher temperatures. An infinite characteristic temperature T_o can be realized at certain ranges of temperature depending on the detuning value     

Long-wavelength strained quantum-well lasers oscillating up to210°C on InGaAs ternary substrates

Long-wavelength InGaAs-InAlGaAs strained quantum-well lasers have been fabricated on In_0.22Ga_0.78As ternary substrates grown by the Bridgman method. The threshold current density and lasing wavelength at 20°C are 245 A/cm² and 1.226 μm, respectively. The device has lased up to 210°C, which is the highest operating temperature ever reported for long-wavelength semiconductor lasers. The temperature sensitivity of the slope efficiency between 20°C and 120°C is only -0.0051 dB/K, showing suppressed carrier overflow owing to deep potential quantum wells. These high-temperature durabilities of this laser are fascinating features for application to optical subscriber and optical interconnection systems     

High-temperature, low threshold current, and uniform operation1×12 monolithic AlGaInAs/InP strain-compensated multiple quantumwell laser array in 1.5 μm

In this paper, we describe the fabrication of a monolithically integrated 1×12 array of 1.5-μm AlGaInAs/InP strain-compensated multiple-quantum-well (MQW) lasers, which has high reliability and highly uniform characteristics in low threshold current, slope efficiency, and lasing wavelength. Besides, each diode on the array exhibits a high characteristic temperature of 88 K and a low slope-efficiency drop of less than 1 dB between 20-80°C and a lasing wavelength of 1510 nm at 20°C and 20 mA. Also, the diode on the array has a maximum resonance frequency of above 8 GHz or 3-dB modulation bandwidth of 12 GHz     

85°C investigation of uncooled 10-Gb/s directly modulatedInGaAsP RWG GC-DFB lasers

The 10-Gb/s directly modulated performance of InGaAsP ridge waveguide (RWG) gain coupled (GC) DFB lasers is investigated up to 85°C. At room temperature, devices have relaxation oscillation frequencies f_relax greater than 20 GHz and damping Γ greater than 100 GHz, f_relax is greater than 6 GHz at 85°C. Constant output power or extinction ratio are possible from 25°C to 75°C chip temperature, with open eyes observable up to 85°C. Back-to-back transmission measurements in a Nortel Networks OC-192 system show error free transmission of a 2²³-1 pseudorandom bit sequence at 83°C     

A temperature-dependent SOI MOSFET model for high-temperatureapplication (27 °C-300 °C)

A temperature-dependent model for long-channel silicon-on-insulator (SOI) MOSFETs for use in the temperature range 27 °C-300 °C, suitable for circuit simulators such as SPICE, is presented. The model physically accounts for the temperature-dependent effects in SOI MOSFETs (such as threshold-voltage reduction, increase of leakage current, decrease of generation due to impact ionization, and channel mobility degradation with increase of temperature) which are influenced by the uniqueness of SOI device structure, i.e. the back gate and the floating film body. The model is verified by the good agreement of the simulations with the experimental data. The model is implemented in SPICE2 to be used for circuit and device CAD. Simple SOI CMOS circuits are successfully simulated at different temperatures     

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     

Room temperature (34°C) operation of strain-compensated quantumcascade lasers

A short wavelength (λ-3.5 μm) strain-compensated In_xGa_(1-x)As/In_yAl_(1-y)As quantum cascade laser is reported. Quasi-continuous wave operation of this device at 34°C with an output power of 11.4 mW persisted for more than 30 minutes without obvious degradation. A very low threshold current density of 1.2 KA/cm² at this temperature was observed     

Wide temperature (-20°C-95°C) operation of an uncooled2.5-Gb/s 1300-nm DFB laser

This letter describes a 2.5-Gb/s 1300-nm distributed feedback laser that can operate in a wide temperature range of -20°C to 95°C. We present RF and DC characteristics of the device and the statistical distribution of threshold current and slope efficiency at high temperature. Finally, we demonstrate the device performance in a 2.5-Gb/s small-form-factor module up to 85°C     

A new GaAs technology for stable FETs at 300°C

A technology for the fabrication of GaAs devices for operation at 300°C is presented. The high reliability of the devices is mainly due to diffusion barrier of WSi₂ in the ohmic contacts and to an optimized Si₃N₄ passivation. It is shown that MESFETs produced with this technology demonstrate a remarkable stability of their characteristics, even after 100 h of storage at 300°C, and only a little degradation after 100 h at 400°C