Continuous-wave type-II “QW” lasers emitting atλ=5.4-7.1 μm

Optically pumped type-II QW lasers emitting in the 5.4-7.1 -μm wavelength range and at continuous-wave (CW) temperatures up to 210 K are demonstrated. At 80 K, the maximum CW output power from a 40-μm-wide pump stripe is 48 mW at 5.41 μm and 31 mW at 6.05 μm. Epitaxial-side-down heat sinking is provided by a new diamond-pressure-bond mounting technique, which requires minimal processing and maintains topside optical access     

Efficient Nd:YAG slab longitudinally pumped by diode lasers

An efficient scalable 1.06-μm continuous-wave (CW) Nd:YAG slab laser longitudinally pumped by diode lasers is discussed. The 809-nm diode radiation is focused into every laser channel emerging from the reflection points of the 1.06-μm beam on the coated slab surfaces. A maximum CW TEM₀₀ output power of 675 mW has been obtained at a diode pump power of 2 W resulting in a slope efficiency of 40%     

Tunable single-frequency Yb:YAG laser with 1-W output power usingtwisted-mode technique

A diode-pumped, single-frequency Yb:YAG laser with >1-W CW output power has been demonstrated. Single-frequency operation is induced by using the twisted-mode technique, and an etalon has also been inserted into the cavity for timing. Single-frequency tuning from 1.02898-1.03174 μm has been achieved with a 116-μm-thick etalon; the tuning range was limited by the etalon's free spectral range     

A sub-1 mA 1.5-GHz silicon bipolar dual modulus prescaler

This paper describes a 2.7-V dual modulus (÷64/65, ÷128/129) prescaler that operates up to 1.5 GHz with a power consumption of 1.97 mW (Vcc=2.3 V, Icc=860 μA). The prescaler also incorporates a stand-by mode feature, which reduces its power dissipation to 0.12 mW when enabled. This performance has been achieved on a 0.8-μm advanced bipolar technology     

Frequency measurements of 9- and 10-μm N2O lasertransitions

We have measured frequencies of N₂O transitions by heterodyning sub-Doppler fluorescence-stabilized N₂O laser radiation with that from a reference CO₂ laser. A high-resolution cavity incorporates a ribbed tube and a highly reflective grating, permitting the CW oscillation of both the 10⁰ 0-02⁰0 9-μm and the 10⁰0-00⁰1 10-μm regular bands. This is the first sub-Doppler frequency measurement of the 9-μm band. The accuracy in the determination of the rotational constants for both bands has been improved by an order of magnitude, and calculated transition frequencies are presented     

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     

An efficient 1.46 μm thulium fiber laser via a cascade process

Continuous wave (CW) lasing in a thulium-doped fluorozirconate fiber at 1.46 μm with a 20% slope efficiency was observed. Simultaneous lasing at 1.86 μm with 29% slope efficiency depopulates the normally long lived 1.46-μm terminal level. It is shown that the cascade process can increase the slope efficiency η_s, of the 1.45-μm transition by a factor of ten and the 1.86-μm transition by a factor of eight. Calculations indicate that the CW laser thresholds decrease significantly     

1.2-μm GaAsP/InGaAs strain compensated single-quantum-well diodelaser on GaAs using metal-organic chemical vapor deposition

We demonstrate here 1.2-μm laser emission from a GaAsP-InGaAs strain compensated single-quantum-well (SQW) diode. This development enables the fabrication of vertical-cavity surface-emitting lasers for optical interconnection through Si wafers. Strain compensation and low temperature growth were used to extend the wavelength of emission to the longest yet achieved on a GaAs substrate in this materials system. The minimum threshold density achieved was 273.4 A/cm² at a cavity length of 610 μm. We have also demonstrated an 1.144-μm lasing wavelength in a 820-μm-long cavity on a GaAs substrate with a strained InGaAs-GaAs SQW laser for comparison using a low-temperature metal-organic chemical vapor deposition growth technique. The threshold current density for a 590-μm-long cavity under CW operation was 149.7 A/cm²     

Mode-locked operation of a Nd:YLF laser and amplification in aQ-switched Nd:glass slab laser

A Nd:YLF laser pumped with a CW dye laser and acoustooptically mode locked at 38 MHz has an output power of 130 mW and a pulse length of 60 ps. Insertion of intracavity etalons and misaligning the mode locker allows for stable operation with a continuous range of pulse lengths from 60 ps to 4 ns. The 1.053-μm emission permits amplification of these pulses in a Q-switched Nd:phosphate glass slab laser oscillator up to intensities limited by optical damage     

Ho:YAG laser pumped by 1.9-μm diode lasers

A 21-μm Ho:YAG laser end pumped by 1.9-μm diode lasers has generated nearly 0.7-W CW output power. Laser operation was maintained even with Ho:YAG heat sink temperatures in excess of 60°C     

High-power high-efficiency quasi-CW Sb-based mid-IR lasers using1.9-μm laser diode pumping

Power efficiency is a critical issue for mid-infrared (mid-IR) semiconductor lasers. Previously, the highest power and efficiency 4-μm laser was pumped with 0.98-μm laser diode. This letter used 1.9-μm diode pumping for better quantum defect ratio and heat flow geometry. A 3.7-μm InAsSb-AlAsSb laser yielded a pump-power-limited 1.25-W single-ended output in 1-ms-long pulse with 6.5% net optical-to-optical efficiency, in contrast with a 0.67-W thermally limited output and 2.7% efficiency with 0.98-μm diode pumping, at 70 K. The results are believed to represent the highest quasi-continuous-wave power from a single device, highest efficiency, and, scaled to the emitting aperture, highest power density for any 3-4-μm semiconductor laser for 1-ms pulse and ⩾70 K     

1.3-μm CW lasing of InGaAs-GaAs quantum dots at room temperaturewith a threshold current of 8 mA

We demonstrate the first 1.3-μm continuous-wave (CW) lasing at room temperature of self-assembled InGaAs-GaAs quantum dots. High-density 1.3-μm emission dots were successfully formed by the combination of low-rate growth and InGaAs-layer overgrowth methods of molecular beam epitaxy. The 1.3-μm ground-level CW lasing occurred at up to 40°C, and the threshold current of 8 mA at 25°C is less than one thirtieth of values ever reported for 1.3-μm dot pulse lasers. The achievement represents a milestone for creating quantum-dot lasers applicable to fiber-optic communication system     

High temperature, high power InGaAs/GaAs quantum-well lasers withlattice-matched InGaP cladding layers

The authors report the high-temperature and high-power operation of strained-layer InGaAs/GaAs quantum well lasers with lattice-matched InGaP cladding layers grown by gas-source molecular beam epitaxy. Self-aligned ridge waveguide lasers of 3-μm width were fabricated. These lasers have low threshold currents (7 mA for 250-μm-long cavity and 12 mA for 500-μm-long cavity), high external quantum efficiencies (0.9 mW/mA), and high peak powers (160 mW for 3-μm-wide lasers and 285 mW for 5-μm-wide laser) at room temperature under continuous wave (CW) conditions. The CW operating temperature of 185°C is the highest ever reported for InGaAs/GaAs/InGaP quantum well lasers, and is comparable to the best result (200°C) reported for InGaAs/GaAs/AlGaAs lasers     

Delay time analysis for 0.4- to 5-μm-gate InAlAs-InGaAs HEMTs

InAlAs-InGaAs HEMTs with 0.4- to 5-μm gate lengths have been fabricated and a maximum f_T of 84 GHz has been obtained by a device with a 0.4-μm gate length. A simple analysis of their delay times was performed. It was found that gradual channel approximation with a field-dependent mobility model with E_c of 5 kV/cm holds for long-channel devices (L _g>2 μm), while a saturated velocity model with a saturated velocity of 2.7×10⁷ cm/s holds for short-channel devices (L_g<1 μm)     

Operating characteristics of high continuous power (50 W)two-dimensional surface-emitting lase array

Monolithic two-dimensional surface-emitting laser (SEL) arrays suitable for both optoelectronic and high power applications were fabricated utilizing a 4-μm×450-μm InGaAs single mode real refractive index guided gain cavity with 90° and 45° ion milled facets. A total CW output power exceeding 50 W was achieved at λ≈944 nm from a monolithic 16×94 2-D SEL array. The 50-W CW output power level is approximately ten times greater than previously demonstrated from a 2-D monolithic SEL array. Greater than 150 h of continuous operation of a 2-D SEL array at 25 W CW was demonstrated     

Gain recovery of bulk semiconductor optical amplifiers

The gain recovery time of 1.55-μm bulk semiconductor optical amplifiers (SOA's) with lengths from 500 to 1500 μm has been measured with a continuous-wave (CW) probe in the time domain. It is shown to decrease with increasing length down to 60 ps for the longest SOA. This behavior is theoretically explained. A lower limit for the recovery time is observed and explained     

High-temperature CW operation of InGaAsP-InP semi-insulating buriedheterostructure lasers using reactive ion-etching technique

We fabricated 1.5-μm semi-insulating buried heterostructure (SI-BH) lasers with InGaAsP-InP strained-layer multiple-quantum wells using a reactive ion etching (RIE) technique for mesa definition. A very high CW operating temperature of 150°C was obtained in a 300-μm-long laser whose rear facet was HR-coated     

An SOI-DRAM with wide operating voltage range by CMOS/SIMOXtechnology

An SOI-DRAM test device (64-Kb scale) with 100-nm-thick SOI film has been fabricated in 0.5-μm CMOS/SIMOX technology and the basic DRAM function has been successfully observed. A partially depleted transistor was used to solve the floating-body effect, resulting in improved operation. The newly introduced body-synchronized sensing scheme enhances the lower Vcc margin. The p-n junction capacitance between source/drain and a substrate for SOI structure is reduced by 25%. RAS access time tRAC is 70 ns with a 2.7-V power supply, which is as fast as the equivalent bulk-Si device with a 4-V power supply. The active current consumption is 1.1 mA (Vcc=3.0 V, 260-ns cycle) for this SOI-DRAM, which is a reduction of 65%, compared with 3.2 mA for the reference bulk-Si DRAM. The mean value of data retention time for this chip at 80°C is longer than 20 s (Vcc=3.3 V), which is the same value as mass-produced 16-Mb DRAM's. The SOI-DRAM has an operating Vcc range from 2.3 V to 4.0 V. The observed speed enhancement and the wide operating voltage range indicate high performance at the low voltage operation suitable for battery-operated DRAM's     

High-power temperature-insensitive gain-offset InGaAs/GaAsvertical-cavity surface-emitting lasers

The authors have grown 997 nm vertical-cavity surface-emitting lasers with an offset between the wavelength of the cavity mode and the quantum well gain peak to improve high temperature operation, and with higher aluminum-content barriers around the active region to improve the carrier confinement. They fabricated lasers of 8-15 and 20-μm diameters. The 8-μm-diameter devices exhibited CW operation up to 140°C with little change in threshold current from 15°C to 100°C, and the 20-μm-diameter devices showed CW output power of 11 mW at 25°C without significant heat sinking