Stable mode-locked operation up to 80 /spl deg/C from an InGaAs quantum-dot laser

We demonstrate the mode-locked operation of a two-section quantum-dot laser in a broad temperature range. Stable mode-locking was observed at temperatures ranging from 20 /spl deg/C to 70 /spl deg/C, with signal-to-noise ratios well over 20 dB and a -3-dB linewidth smaller than 80 kHz. In the temperature range between 70 /spl deg/C and 80 /spl deg/C, the mode-locking was less stable. It was found that in order to provide stable mode-locked operation with increasing temperature, the reverse bias on the absorber section must be reduced accordingly.     

Continuous-wave operation up to 36/spl deg/C of 1.3-/spl mu/m GaInAsP-InP vertical-cavity surface-emitting lasers

We introduced ion-beam assisted deposition in order to improve the quality of Al/sub 2/O/sub 3/ and SiO/sub 2/, which were used as part of the mirrors of 1.3-/spl mu/m GaInAsP-InP vertical-cavity surface-emitting lasers (VCSELs). The refractive index of Al/sub 2/O/sub 3/ was improved to 1.63 from 1.56 and the one of SiO/sub 2/ increased to 1.47 from 1.45. Low-threshold room-temperature continuous-wave (CW) operation of 1.3-/spl mu/m VCSEL with the improved mirrors was demonstrated. The threshold current was 2.4 mA at 20/spl deg/C. The CW operating temperature was raised to 36/spl deg/C, which is a record high temperature for 1.3-/spl mu/m VCSEL.     

Characterization of the temperature sensitivity of gain and recombination mechanisms in 1.3-/spl mu/m AlGaInAs MQW lasers

The potential of 1.3-/spl mu/m AlGaInAs multiple quantum-well (MQW) laser diodes for uncooled operation in high-speed optical communication systems is experimentally evaluated by characterizing the temperature dependence of key parameters such as the threshold current, transparency current density, optical gain and carrier lifetime. Detailed measurements performed in the 20/spl deg/C-100/spl deg/C temperature range indicate a localized T/sub 0/ value of 68 K at 98/spl deg/C for a device with a 2.8 /spl mu/m ridge width and 700-/spl mu/m cavity length. The transparency current density is measured for temperatures from 20/spl deg/C to 60/spl deg/C and found to increase at a rate of 7.7 A/spl middot/cm/sup -2//spl middot/ /spl deg/C/sup -1/. Optical gain characterizations show that the peak modal gain at threshold is independent of temperature, whereas the differential gain decreases linearly with temperature at a rate of 3/spl times/10/sup -4/ A/sup -1//spl middot//spl deg/C/sup -1/. The differential carrier lifetime is determined from electrical impedance measurements and found to decrease with temperature. From the measured carrier lifetime we derive the monomolecular ( A), radiative (B), and nonradiative Auger (C) recombination coefficients and determine their temperature dependence in the 20/spl deg/C-80/spl deg/C range. Our study shows that A is temperature independent, B decreases with temperature, and C exhibits a less pronounced increase with temperature. The experimental observations are discussed and compared with theoretical predictions and measurements performed on other material systems.     

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.     

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.     

Bias point thermal shift growth in Z-cut LiNbO/sub 3/ Modulators

Growth of a bias point thermal shift induced by dc bias in z-cut LiNbO/sub 3/ optical intensity modulators is quantitatively discussed from the standpoint of its impact on field service. During 20 years of device operation under a worst-case dc bias condition, the thermal shift slope grows almost symmetrically with respect to a bias polarity. An initial small thermal shift of around /spl plusmn/7 mV//spl deg/C (3/spl sigma/ distribution bounds) increases continuously over time with biased operation at 55/spl deg/C and approaches /spl plusmn/70 mV//spl deg/C after 20 years. This increased temperature sensitivity would generate approximately a 2-V bias point shift toward the bias rail when modulator is exposed to temperature variation from 55/spl deg/C to 25/spl deg/C.     

Uncooled high-temperature (130/spl deg/C) operation of InGaAs-GaAs multiple quantum-well lasers at 20 Gb/s

Short-haul fiber-optic communication systems require high-speed semiconductor lasers that can operate uncooled over a wide temperature range. In this letter, we describe high-speed short-cavity InGaAs-GaAs multiple-quantum-well lasers operating at 1.1-/spl mu/m wavelength. The Fabry-Perot lasers were fabricated in a triple-mesa geometry suitable for on-wafer probing. With 3/spl times/200 /spl mu/m/sup 2/ ridge-waveguide lasers, which showed the best compromise between high-temperature and high-speed performance, a 3-dB modulation bandwidth of 14.5 GHz at 130/spl deg/C was achieved. Uncooled 20-Gb/s operation of these lasers is presented over a wide-temperature range from 25/spl deg/C to 130/spl deg/C without automatic power control.     

The thermal stability of one-transistor ferroelectric memory with Pt-Pb/sub 5/Ge/sub 3/O/sub 11/-Ir-poly-SiO/sub 2/-Si gate stack

The thermal stability of one-transistor ferroelectric nonvolatile memory devices with a gate stack of Pt-Pb/sub 5/Ge/sub 3/O/sub 11/-Ir-Poly-SiO/sub 2/-Si was characterized in the temperature range of -10/spl deg/C to 150/spl deg/C. The memory windows decrease when the temperatures are higher than 60/spl deg/C. The drain currents (I/sub D/) after programming to on state decrease with increasing temperature. The drain currents (I/sub D/) after programming to off state increase with increasing temperature. The ratio of drain current (I/sub D/) at on state to that at off state drops from 7.5 orders of magnitude to 3.5 orders of magnitude when the temperature increases from room temperature to 150/spl deg/C. On the other hand, the memory window and the ratio of I/sub D/(on)/I/sub D/(off) of the one-transistor memory device displays practically no change when the temperature is reduced from room temperature to -10/spl deg/C. One-transistor (1T) memory devices also show excellent thermal imprint properties. Retention properties of 1T memory devices degrade with increasing temperature over 60/spl deg/C.     

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     

High sensitive and wide detecting range MOS tunneling temperature sensors for on-chip temperature detection

This paper examined the feasibility of applying a highly sensitive metal-oxide-semiconductor (MOS) tunneling temperature sensor, which was compatible with current CMOS technology. As the sensor was biased positively at a constant voltage, the gate current increased more than 500 times when the sensor was heated from 20/spl deg/C to 110/spl deg/C. However, when the sensor was biased at a constant-current situation, its gate voltage magnitude changed significantly with substrate temperature, with a sensitivity exceeding -2 V//spl deg/C. The improvement of temperature sensitivity in this paper is one thousand times over the sensitivity of a conventional p-n junction, i.e., namely, about -2 mV//spl deg/C. Regarding a temperature sensor array, this paper proposes a method using gate current gain, rather than absolute gate current, to eliminate the gate current discrepancy among sensors. For constant current operation, a sensitivity exceeding 10 V//spl deg/C can be obtained if the current level is suitable. Finally, this paper demonstrates a real temperature distribution for on-chip detection. With such a high temperature-sensitive sensor, accurate temperature detection can be incorporated into common CMOS circuits.     

1-GHz, 200/spl deg/C, SiC MESFET Clapp oscillator

A SiC Clapp oscillator fabricated on an alumina substrate with chip capacitors and spiral inductors is designed for high-temperature operation at 1GHz. The oscillator operated from 30/spl deg/C to 200/spl deg/C with an output power of 21.8dBm at 1GHz and 200/spl deg/C. The efficiency at 200/spl deg/ C is 15%. The frequency variation over the temperature range is less than 0.5%.     

Room-temperature 2.81-/spl mu/m continuous-wave operation of GaInAsSb-AlGaAsSb laser

GaInAsSb-AlGaAsSb multiple quantum-well (QW) lasers with an emission wavelength of 2.81 /spl mu/m are reported. The ridge waveguide lasers with highly strained QWs show continuous-wave laser emission up to 25/spl deg/C; in pulsed mode, the lasers operate up to 60/spl deg/C. For pulsed operation, a threshold current density of 360 A/cm/sup 2/ is found for devices with 30-/spl mu/m stripe width and 2-mm cavity length at room temperature. A low threshold current density at infinite length of 248 A/cm/sup 2/ is derived.     

A CMOS smart temperature sensor with a 3/spl sigma/ inaccuracy of /spl plusmn/0.5/spl deg/C from -50/spl deg/C to 120/spl deg/C

A low-cost temperature sensor with on-chip sigma-delta ADC and digital bus interface was realized in a 0.5 /spl mu/m CMOS process. Substrate PNP transistors are used for temperature sensing and for generating the ADC's reference voltage. To obtain a high initial accuracy in the readout circuitry, chopper amplifiers and dynamic element matching are used. High linearity is obtained by using second-order curvature correction. With these measures, the sensor's temperature error is dominated by spread on the base-emitter voltage of the PNP transistors. This is trimmed after packaging by comparing the sensor's output with the die temperature measured using an extra on-chip calibration transistor. Compared to traditional calibration techniques, this procedure is much faster and therefore reduces production costs. The sensor is accurate to within /spl plusmn/0.5/spl deg/C (3/spl sigma/) from -50/spl deg/C to 120/spl deg/C.     

Electrically pumped room temperature CW VCSELs with 2.3 /spl mu/m emission wavelength

Continuous wave (CW) operation at room temperature of electrically pumped InGaAlAs/InP vertical-cavity surface-emitting lasers (VCSELs) at emission wavelengths as high as 2.3 /spl mu/m is demonstrated for the first time. Devices with 15 /spl mu/m active region diameter show a maximum output power of 0.75 mW at 20/spl deg/C and a maximum CW operating temperature of 45/spl deg/C.     

1550 nm-band VCSEL 0.76 mW singlemode output power in 20-80/spl deg/C temperature range

Wafer-fused InGaAlAs/AlGaAs vertical cavity surface emitting lasers with InAlGaAs-based tunnel junction injection have shown record high 0.7 mW singlemode output power in the 10-80/spl deg/C temperature range. Single transverse-mode operation with 35 dB sidemode suppression and low divergence beam with 9/spl deg/ half width at half maximum has been measured on devices with 7 /spl mu/m aperture.     

Continuous-wave operation of 5 /spl mu/m quantum cascade lasers with high-reflection coated facets

A report is presented on the continuous-wave operation of /spl lambda//spl sime/5 /spl mu/m GaInAs/AlInAs/InP-based quantum cascade lasers up to a heatsink temperature of 222 K (-51/spl deg/C). The devices are mounted epi-side down with high-reflection coated facets. The dissipated electrical power at threshold amounts to only 2.3 W at 222 K.     

Low-threshold high-T/sub 0/ 1.3-/spl mu/m InAs quantum-dot lasers due to p-type modulation doping of the active region

P-type doping is used to demonstrate high-To, low-threshold 1-3 /spl mu/m InAs quantum-dot lasers. A 5-/spl mu/m-wide oxide confined stripe laser with a 700-/spl mu/m-long cavity exhibits a pulsed T/sub 0/ = 213 K (196 K CW) from 0/spl deg/C to 80/spl deg/C. At room temperature, the devices have a CW threshold current of /spl sim/4.4 mA with an output power over 15 mW. The threshold at 100/spl deg/C is 8.4 mA with an output power over 8 mW.     

1.50 /spl mu/m CW operation of GaInNAs/GaAs laser diodes grown by MOCVD

Room-temperature continuous-wave operation of a 1.5 /spl mu/m range GaInNAs laser grown by metal organic chemical vapour deposition is reported. The lasing wavelength of the GaInNAs/GaAs double quantum well laser was 1.50 /spl mu/m and the threshold current was 245 mA. The characteristic temperature between 10 and 50/spl deg/C was about 119 K under pulse operation.     

Wavelength and power stabilisation of uncooled 975 nm thick quantum well lasers over 110/spl deg/C temperature range

The use of a thick quantum well enables coherence-collapse operation of a Bragg grating stabilised laser diode over 110/spl deg/C temperature range, yielding 975 nm wavelength emission with >40 dB sidemode suppression ratio, <1% power variation, and fibre-output power as high as 293 mW at 15/spl deg/C and 168 mW at 125/spl deg/C.     

SiC thin-film Fabry-Perot interferometer for fiber-optic temperature sensor

Polycrystalline SiC grown on single-crystal sapphire substrates have been investigated as thin-film Fabry-Perot interferometers for fiber-optic temperature measurements in harsh temperatures. SiC-based temperature sensors are compact in size, robust, and stable at high temperatures, making them one of the best choices for high temperature applications. SiC films with thickness of about 0.5-2.0 /spl mu/m were grown at 1100/spl deg/C by chemical vapor deposition (CVD) with trimethylsilane. The effect of operating temperature on the shifts in resonance minima, /spl Delta//spl lambda//sub m/, of the SiC/sapphire substrate has been measured in the visible-infrared wavelength range. A temperature sensitivity of 1.9/spl times/10/sup -5///spl deg/C is calculated using the minimum at /spl sim/700 nm. Using a white, broadband light source, a temperature accuracy of /spl plusmn/3.5/spl deg/C is obtained over the temperature range of 22/spl deg/C to 540/spl deg/C.