Crescent Laser Diodes Research Articles

Regime where zero-bias is the low-power solution for digitally modulated laser diodes

We demonstrate that when a laser diode is digitally modulated with zero-bias, the average electrical power consumption can be less than a threshold-biased scheme for the same bit error rate. We find that the power consumption of large threshold >10 mA lasers with zero-bias is comparable to or less than with threshold-bias modulation as long as B/spl tau/<1/ln(2), where B and /spl tau/ are the bit rate and the laser's carrier lifetime, respectively. Experiments with a buried crescent laser diode confirm this claim at both 300 K and 77 K. The power penalty of zero-bias at higher bit rates is also discussed.

Optical multi-stable set-reset functions of optoelectronic integrated device composed of six heterojunction phototransistors over two laser diodes

An optoelectronic integrated device composed of six heterojunction phototransistors epitaxially integrated over two buried crescent laser diodes is developed. The integrated device provides internal electro-optical coupling among constituent components. The coupling has an important role to achieve several optical functions quite appropriate for the fields of neural network and optical information processing. With a proper combination of the constituent devices, the integrated device exhibits tetra-stable set-reset function (extendable to penta-stable set-reset function) when external optical pulses are incident to the device. Physics and mechanism of the device operation are discussed in detail and the experimental results are presented.

Threshold currents of 1.2-1.55 mu m P-substrate buried crescent laser diodes

P-substrate buried crescent (PCB) laser diodes whose wavelength ranged from 1.2 to 1.55 mu m have been fabricated. The threshold currents as low as 10 mA have been obtained in this wavelength range experimentally. The calculated threshold currents of 13, 13, and 14 mA at 1.2, 1.3, and 1.55 mu m almost coincide with the measured values. >

Wavelength dependence of characteristics of 1.2-1.55 mu m InGaAsP/InP p-substrate buried crescent laser diodes

Laser diodes with the p-substrate buried-crescent structure have been fabricated for the 1.2-1.55- mu m wavelength region. The dependence of laser characteristics on wavelength has been measured. Up to 70 degrees C, the increasing rates of the threshold current with temperature are similar, while, above 70 degrees C, a shorter-wavelength laser shows a larger increasing rate. At the same full width at half maximum of the far-field pattern perpendicular to the junction plane, the external differential quantum efficiency of the 1.55- mu m laser diode is only 10% smaller than that of the 1.3- mu m laser. The absorption loss coefficients in the active layer of the 1.2-, 1.3-, and 1.55- mu m laser are estimated to be 26, 34, and 73 cm/sup -1/, respectively.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

High-power high-reliability operation of 1.3 µm p-substrate buried crescent laser diodes

Stable high-power CW operation of 1.3-μm InGaAsP/InP p-substrate buried crescent laser diodes (PBC-LD'S) has been realized, by controlling the front and rear facet reflectivities of the laser diode chips. The front facet reflectivity is reduced to 17 percent and the rear facet reflectivity is increased to 90 percent, by evaporating multilayer dielectric films (Si/Al 2 O 3 SiO 2 :17 percent, SiO 2 /Si/SiO 2 /Si/SiO 2 :90 percent) on each facet. CW light output power of 50 mW is achieved up to 60°C. Aging tests have been carried out under automatic power control (APC) mode conditions of 50°C-30 mW, 40 mW, 50 mW, and 30°C-50 mW. All samples are operating stably in spite of junction-up configuration. The lifetimes are estimated to be more than 2 \times 10^{4} h for all conditions.

High temperature CW operation of p -substrate buried crescent laser diode emitting at 1.3 μm

A 1.3 μm InGaAsP/InP buried crescent laser diode has been fabricated on p-InP substrate. The laser diode has a low threshold current, as low as 10 mA. It operates at the output power of 5 mW under CW condition at temperatures higher nary aging test at 70°C with a constant light output of 5 mW, the lasers have been operating stably for more than 1000 h.

InGaAsP/InP buried crescent laser diode emitting at 1.3 µm wavelength

The fabrication procedure, designing of an active region and a p-n-p-n current blocking structure, characteristics and the aging results of an InGaAsP/InP buried crescent (BC) laser diode are described. The BC laser diodes exhibit high laser performances, such as a low-threshold current, a fundamental transverse mode oscillation with linear light output-current characteristics. CW operation at as high as 100°C is achieved with a junction up configuration as a result of the improvement in the current blocking structure. A stable CW operation at 80°C has been realized with a constant optical output power of 5 mW.

Degradation mechanism in 1.3 μm InGaAsP/InP buried crescent laser diode at a high temperature

A leakage current flowing through a junction between a p-InP current blocking layer and an n-InP cladding layer is examined in connection with a degradation of a buried crescent laser diode at a high temperature. The degradation characteristics have been successfully explained by a theoretical model proposed in this study.

Transverse mode control in InGaAsP/InP buried crescent diode lasers

Transverse mode stabilisation of InGaAsP/InP buried crescent laser diodes emitting at 1.3 ?m is described. Width and thickness of the active region have been reduced to stabilise the transverse mode. Operation up to 17 mW/facet in a stable transverse mode and threshold current as low as 12 mA in CW operation have been obtained.