Extremely small active stripe laser diodes (EXSAS-LDs) for 17channel low threshold array

A uniform 17-channel array of low-threshold (3.5 mA, average) 1.3 μm-wavelength lasers was realised with submicrometre-wide bulk active stripes grown by selective MOVPE     

High-temperature (130 degrees C) CW operation of 1.53 mu m InGaAsP ridge-waveguide lasers using strained quaternary quantum wells

Minimum threshold current density of 0.57 kA/cm/sup 2/ and high T/sub 0/ values up to 74 K were obtained from 400 mu m long broad area lasers with MOVPE grown compressively strained all-quarternary GaInAsP SCH-MQW layer structures for 1.53 mu m emission wavelength. With 3 mu m*400 mu m RW laser diodes (T/sub 0/>90 K) high-temperature CW operation up to 130 degrees C was achieved.<>     

Reliability and degradation behaviors of semi-insulating Fe-dopedInP buried heterostructure lasers fabricated by RIE and MOVPE

We clarified the degradation behaviors of semi-insulating buried heterostructure lasers in which mesa structures were fabricated by reactive ion etching (RIE) and then buried in semi-insulating Fe-doped InP grown by metal organic vapor phase epitaxy (MOVPE). The degradation rate and mode correlated with the quality of the buried heterostructure (BH) interface. Based on the correlation, a condition for highly stable semi-insulating Fe-doped InP buried heterostructure (SIBH) lasers was demonstrated and confirmed experimentally and statistically     

Spectral linewidth reduction (580 kHz) in structure-optimised 1.5 mu m butt-jointed distributed Bragg reflector lasers

Spectral linewidth reduction due to structural optimisation is studied in butt-jointed DBR lasers. It is theoretically shown that a laser structure with passive DBR regions on both sides of an active region is effective in reducing the linewidth.. Based on theoretical calculation, 1.5 mu m butt-joined DBR lasers are fabricated entirely by MOVPE growth. Linewidth is reduced to 580 kHz in structure-optimised 1.5 mu m butt-jointed DBR lasers.<>     

Reliability and degradation behaviors of semi-insulating Fe-doped InP buried heterostructure lasers fabricated by movpe and dry etching technique

We clarified the degradation behavior of semi-insulating buried heterostructure lasers in which mesa structures were fabricated by RIE and then buried by MOVPE. The degradation rate and mode correlated with the quality of the BH interface. Based on the correlation, a condition for highly stable SIBH lasers was demonstrated and confirmed experimentally and statistically.     

Self-assembled quantum dots

The greatest success in semiconductor lasers has been brought by the ability to artificially structure new materials on an atomic scale by using advanced crystal growth methods such as MBE and MOVPE. Laser performance successes gained using quantum wells in optoelectronic devices can be extended by adopting quantum wire and quantum dot structures. There have been several reports of successful lasing action in semiconductor dot structures within the past year. This article reviews the recent progress in the development of quantum dot lasers.     

High-power long-wavelength room-temperature MOVPE-grown quantum cascade lasers with air-semiconductor waveguide

Quantum cascade lasers grown by metal organic vapour phase epitaxy (MOVPE) with high peak output power of 1.3 W at 300 K emitting a wavelength of 9.8 mum are reported. The devices are processed in wide ridge waveguide structures with an air-semiconductor interface to confine the laser optical mode. This design increases the optical overlap factor and reduces waveguide losses.     

Novel strained quantum well laser grown by MOVPE

Strained-layer broad-area lasers have been grown by MOVPE. The structures contain 3.5 nm-wide Ga/sub 0.3/In/sub 0.7/As quantum wells. They emit close to 1.5 mu m and have been made to lase under current injection. These structures were compared with similar lasers containing unstrained 7.0 nm-wide Ga/sub 0.47/In/sub 0.53/As quantum wells also emitting at 1.5 mu m. No improvement has been found in J/sub th/ (933 A cm/sup -2/) or T/sub 0/ (47 K) in the case of the strained structure, despite the expected band structure modification.<>     

MOVPE growth of AlGaAs/GaInP diode lasers

GaAs-based diode lasers for emission wavelengths between 800 nm and 1060 nm with AlGaAs-cladding and GaInP-waveguide layers were grown by MOVPE. For wavelengths above 940 nm broad area devices with InGaAs QWs show state-of-the-art threshold current densities. Ridge-waveguide lasers fabricated by selective etching achieve 200 mW CW monomode output powers. (In)GaAsP QW-based diode lasers with an emitting wavelengths around 800 nm suffer from problems at the upper GaInP/AlGaAs interface. Asymmetric structures with a lower AlGaAs/GaInP and an upper AlGaAs/AlGaAs waveguide not only avoid this interface but also offer better carrier confinement. Such structures show very high slope efficiencies and a high T₀. Maximum output powers of 7 W CW are obtained from 4 mm long devices.     

Room temperature visible (683-713 nm) all-AlGaAs vertical-cavity surface-emitting lasers (VCSELs)

Visible emitting all-AlGaAs vertical-cavity surface-emitting lasers (VCSELs) have been produced by metal organic vapor phase epitaxy (MOVPE) using ultra-high purity source reagents. Lasing was obtained at wavelengths in the range 683-713 nm using four 45 /spl Aring/ Al/sub 0.18/Ga/sub 0.82/As quantum wells in the active region. At room temperature, a minimum threshold current density of 3.8 kA.cm/sup -2/ was measured for a wavelength of 692 nm; this is the lowest value for an all-AlGaAs vertical-cavity laser operating at this wavelength. Growth of the epitaxial mirrors at 5.2 /spl mu/m/h/sup -1/ results in a total growth time of only two and a half hours.     

Very low-threshold (0.8 kA/cm2)InGaAsP/InP DH 1.5 ?m lasers grown by atmospheric MOVPE

Broad-area lasers have been fabricated from five separate atmospheric MOVPE DH wafers. Good agreement is found with expected theoretical predictions of the threshold/length and active-layer thickness dependences. The FWHM of the radiation in the plane perpendicular to the junction is well described by published values of active and cladding refractive indices.     

Low-threshold piezoelectric-strained InGaAs-GaAs QW lasers grown on (211)B oriented GaAs substrates

We report the operation of strained layer In/sub 0.20/Ga/sub 0.80/As quantum well lasers grown on (211)B GaAs substrates, thus incorporating a piezoelectric field. Growth was by atmospheric pressure metal-organic vapor phase epitaxy (MOVPE). The threshold current density of a 1000 /spl mu/m/spl times/75 /spl mu/m device is 91 A/spl middot/cm/sup -2/ and waveguide transparency is estimated at 32 A/spl middot/cm/sup -2/ for a simple separate confinement heterostructure (SCH) emitting at 982 nm.     

Optimization of GaAsP/AlGaAs-based QW laser structures for high power 800 nm operation

We present a detailed study of the MOVPE growth of 800 nm diode laser structures based on the combination of a GaAsP quantum well with well-established AlGaAs waveguide structures. By optimizing the strain and thickness of the quantum well highly-reliable diode lasers with low threshold current and high efficiency were demonstrated. 100 μm aperture “broad area” devices mounted epi-side up achieve a CW output power of 8.9 W with a wall-plug efficiency of 50%. These output powers represent record values for diode lasers in this wavelength range. Reliability measurements at 1.5 W and 50°C ambient temperature suggest lifetimes >10 000 h.     

Growth and characterization of high yield, reliable, high-power,high-speed, InP/InGaAsP capped mesa buried heterostructure distributedfeedback (CMBH-DFB) lasers

The capped-mesa buried-heterostructure distributed-feedback (CMBH-DFB) laser structure requires three epitaxial growths and is designed to allow good control of the width of the active layer using straightforward chemical etching techniques. The base structure, which contains the active layer, was fabricated using a variety of epitaxial techniques: liquid-phase epitaxy, hydride vapor-phase epitaxy (VPE) and metalorganic vapor-phase epitaxy (MOVPE). The final cap growth was done using hydride VPE. High yields of low-threshold high-power DFB lasers were produced from a number of wafers at emission wavelengths of 1.3 and 1.55 μm     

Two-dimensional numerical analysis of lasing characteristics forself-aligned structure semiconductor lasers

Lasing characteristics in 0.78 μm AlGaAs-GaAs self-aligned structure (SAS) lasers are calculated on the basis of a newly developed two-dimensional analytical method. The calculated results are compared in detail with experimental results for MOVPE (metalorganic vapor phase epitaxial) grown SAS lasers. It is shown that calculated results agree well with experimental results, and that the newly developed two-dimensional simulator is very effective in calculating actual lasing characteristics accurately. The optimum design conditions for AlGaAs-GaAs SAS lasers obtained from experimental and calculated results are discussed     

Advances in self-assembled semiconductor quantum dot lasers

In the past 20 years the semiconductor laser has become a key device in optical electronics because of its pure output spectrum and high quantum efficiency. As the capabilities of laser diodes have grown, so has the range of applications contemplated for them. A great success in semiconductor lasers has been brought by the ability to artificially structure new materials on an atomic scale by using advanced crystal growth methods such as MBE and MOVPE. The laser performance successes gained using quantum wells in optoelectronic devices can be extended by adopting quantum wire and quantum dot structures. There have been several reports of successful lasing action in semiconductor dot structures within the past few years. In this article I will briefly review the recent progress in the development of quantum dot lasers.     

GaInAs/AlGaInAs DH and MQW lasers with 1.5-1.7 mu m lasing wavelengths grown by atmospheric pressure MOVPE

The first successful growth and fabrication of long wavelength (1.5-1.7 mu m) DH and MQW lasers by atmospheric pressure MOVPE in a 'phosphorus-free' material system is reported. The GaInAs/AlGaInAs DH and MQW lasers were grown on InP substrates. DH lasers emitting at around 1690 nm exhibit threshold current densities down to 2.8 kA/cm/sup 2/ at 25 degrees C; the characteristic temperature is 50 K in the 15-55 degrees C range. First MQW lasers with 1565 nm emission wavelength have threshold current densities around 3.2 kA/cm/sup 2/.<>     

Role of molecular beam epitaxy in the field of optoelectronics

This article reviews the role of molecular beam epitaxy (MBE) in the field of optoelectronics. In the past 25 years, this crystal growth technology has helped researchers to investigate important physical phenomena related to materials properties. In particular, success in engineering the band structure and refractive index was a key to the exploration and development of carrier transport devices such as high-mobility, bipolar and tunnel transistors, as well as optoelectronic elements such as LEDs, lasers, modulators and photodetectors. Because of its relatively simple growth process, excellent growth control and ability to characterize growth-related phenomena in situ, MBE initiated many important research fields such as GaAs on silicon, fast optical switches and detectors, and vertical cavity and edge-emitting quantum well lasers, particularly in the GaAs/AlGaAs materials system. In addition, relatively unexplored systems such as II/VI materials, nitrides or even Si/Ge heterostructures, are currently hot topics among MBE crystal growers.

Over the years, the division of the roles of MBE as a research and prototyping tool and metal-organic vapor-phase epitaxy (MOVPE) as a production tool has become well established. However, for certain production processes, specifically compact disc and 980 nm Er-fiber pump lasers, MBE has been proved to be as good or better than MOVPE, even when high throughput is a necessity. New fields, such as devices based on very precise vertical Fabry-Perot cavity designs and low-temperature GaAs, are emerging in which the uniform thickness control, in situ monitoring capability and low-temperature growth ability of MBE offer clear superiority over MOVPE for eventual production.     

Semiconductor pump laser technology

Recent progress in high-power semiconductor lasers for erbium-doped fiber amplifiers is described, focusing on 1.48-μm InGaAsP/InP lasers and 0.98-μm InGaAs/GaAs lasers. The experimental output powers exceed 200 mW (the maximum power was 325 mW) for 1.48-μm lasers, and simulation results indicate that over 400 mW could be obtained by optimizing parameters in strained-layer (SL) multiple-quantum-well (MQW) lasers. Stable operation over a few thousand hours under 100-mW power is demonstrated for liquid-phase-epitaxy-grown lasers, MQW lasers, and SL-MQW lasers grown by all-metal organic vapor-phase epitaxy (MOVPE). For 0.98-μm lasers, improvement in the fiber coupling efficiencies and long-term reliabilities are described. Their power coupled into a single-mode fiber has reached over 100 mW, with coupling efficiencies of approximately 40%. Although reliability seems to be one of the drawbacks compared with 1.48-μm lasers, stable operation for over 10,000 h at 50°C and 30 mW has been reported     

Double heterostructure and multiquantum-well lasers at 1.5?1.7 ?m grown by atmospheric pressure MOVPE

The first successful growth and fabrication of GaInAs/InP MQW and CW GaInAsP DH lasers by atmospheric pressure MOVPE is reported. Room-temperature CW operation of DH lasers was obtained by using the ridge-waveguide laser design, and threshold currents as low as 53 mA were measured. MQW lasers, which also operated at room temperature, were fabricated, and emission spectra obtained from these devices showed a clear spectral narrowing compared with the DH lasers together with a wavelength shift, in good agreement with theoretical predictions.