Nonabsorbing Mirrors Research Articles

Strained-layer InGaAs-GaAs-AlGaAs buried-heterostructurelasers with nonabsorbingmirrors by selective-area MOCVD

Design, fabrication, and operation of strained-layer InGaAs-GaAs-AlGaAs buried-heterostructure (BH) lasers with nonabsorbing mirrors fabricated by selective-area epitaxy (SAE) are presented. The SAE-BH lasers with nonabsorbing mirrors operate at powers up to approximately 325 mW/facet (4 mu m wide output aperture), which is a >40% increase over conventional SAE-BH lasers.

High power single mode operation of long cavity GaAlAs lasers with nonabsorbing mirror buried twin ridge substrate structure

We have newly developed a 350 μm long cavity GaAlAs laser with nonabsorbing mirror buried twin ridge substrate structure, in order to obtain highly reliable high power single mode operation. It is found that the long cavity stabilizes lateral mode at powers higher than conventional maximum values because the carrier density is reduced to well suppress spatial hole-burning effect. The fundamental spatial mode operation is confirmed up to 210 mW and the maximum output power as high as 380 mW is obtained. The lifetime at 100 and 200 mW at 25 °C are expected to be 170 000 and 24 000 h, respectively, from the aging test results.

Power-independent degradation of high-power GaAlAs lasers with nonabsorbing mirrors

The reliability of high-power single-mode GaAlAs lasers with nonabsorbing mirrors (NAMs) was investigated in detail. The lasers were tested at various output powers and temperatures. The aging test was performed under constant power in order to examine the output power dependence. In order to carry out the measurement with accuracy, the heat sink temperature was controlled with an error of +or-0.1 degrees C, and the operating current was measured every hour or every 10 h. As a result, very smooth aging test curves were obtained. Output powers of the coated lasers in the aging tests were 30, 50, and 100 mW, and the temperatures of the heat sink were 50, 70, and 90 degrees C. conventional lasers without a NAM were tested for comparison. The results indicate that the degradation of the lasers is dependent not on the output power, but on the operating current and temperature. The thermal activation energy and the degradation rate is estimated to be 0.85 eV.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Low-noise and high-power operation in high reflectivity coated nonabsorbing mirror GaAlAs lasers

We have successfully attained low-noise and high-power operation in GaAlAs lasers by applying high reflectivity facet coating approach to nonabsorbing mirror lasers. High reflectivity coating is used to reduce feedback induced noise coming from hopping between the diode cavity modes and between the external cavity modes. A nonabsorbing mirror structure is used to obtain high-power operation by suppressing mirror degradation and catastrophic optical damage effectively even with the use of high reflectivity coating. Nonabsorbing mirror lasers with the front facet reflectivity 50% showed the relative intensity noise level less than −130 dB/Hz at 3 mW under 0%–10% optical feedback and showed the cw output power as high as 50 mW in fundamental spatial mode operation. Under 30-mW cw operation at 50 °C, on the other hand, obvious degradation has not been observed over 4000 h in the nonabsorbing mirror lasers with 50% front facet reflectivity. Thus the present laser is useful as a low-noise source at a low-power level and also as a high-power source with high reliability.

Continuous-wave high-power (75 mW) operation of a transverse-mode stabilised window-structure 680 nm AlGaInP visible laser diode

75 mW CW output power was obtained for a transversemode stabilised window-structure 680 nm AlGaInP visible laser diode with non-absorbing mirror facets formed by disordering of GaInP natural superlattice. Stable fundamental mode operations were achieved at up to 70 mW, which is 2.3 times as high as previously reported.

High-power laser diodes with nonabsorbing mirrors.

We succeeded in the phase locked operation of a 5-element GaAIAs diode laser array emitting 0.6W CW. The diodes use nonabsorbing mirrors (NAM's) for the suppression of catastrophic optical damage (COD) and a buried twin ridge substrate (BTRS) structure for the injection current confinement and for the stabilization of a transverse mode.

Highly-reliable CW operation of 100 mW GaAlAs buried twin ridge substrate lasers with nonabsorbing mirrors

Long-life GaAlAs lasers with 100-mW fundamental-transverse-mode operation are discussed. This excellent degree of operation has been attained by using nonabsorbing mirrors for suppression of mirror degradation and a twin-ridge substrate structure for stabilization of the transverse mode. It has been found that under 100 mW CW operation at 50 degrees C, degradation is insignificant even after 6000 h.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

High-power, high-brightness, phase-locked broad-stripe diode lasers

A novel superlinear graded index separate confinement laser diode structure is proposed. Single stripe diode lasers with 210 μm emitting aperture generate 3.2 W cw, and 6.3 W quasi-cw of light-output power in a phase-locked operation. The catastrophic optical density (30 W/mm) obtained for these lasers is better than that reported for devices with nonabsorbing mirrors.

2.4 W CW 770 nm laser arrays with nonabsorbing mirrors

Laser arrays have been fabricated with silicon-impurityinduced disordered nonabsorbing mirrors (windows) to enhance the maximum CW power output. The power output was thermally limited for a 100 ?m-aperture device to 2.4 W CW while catastrophic failure occurred under pulsed conditions at 3.5 W in a 100 ?s pulse and increased to 22 W for a 50 ns pulse. The emission wavelength of these diodes is 770 nm.

Aging behavior and surge endurance of 870-900 nm AlGaAs lasers with nonabsorbing mirrors

The reliability of 870-900 nm AlGaAs TJS lasers has been investigated. An emission wavelength longer than 870 nm is realized by utilizing the band tailing effect due to heavy Zn-diffusion in the active region. A nonabsorbing mirror structure is employed to eliminate both gradual degradation and catastrophic damage of the facets. Stable continuous operation for over 10 000 hours has been confirmed at ambient temperatures higher than 50°C and output powers more than 5 mW/ facet. MTTF longer than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> hours is expected for screened devices. Surge endurance has been improved to be nearly one order of magnitude higher than that for a conventional structure.

Nonabsorbing-mirror (NAM) CDH-LOC diode lasers

CDH-LOC lasers with lateral and transverse mode control in nonabsorbing mirror regions are realised by a single etch-and-regrowth cycle. The maximum achieved peak-pulsed output power (100 ns) and catastrophic-optical-damage (power-density) levels are 1.5 W and (20–30) MW/cm2, respectively. A linear power density of 200 mW/μm is reached at catastrophic damage. Fundamental-mode operation is obtained to 80 mW in narrow beams (θ∥≅7°; θ⟂≅15°).