New design rules and experimental study of slightly flared 1480-nm pump lasers

Guermache, Ali; Voiriot, V.; Capella, R.-M.; Gallion, P.; Jacquet, J.

doi:10.1109/lpt.2006.871640

Cited by 3 publications

(3 citation statements)

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“…Such impact can be mitigated or even totally compensated through tapered waveguide or longitudinal patterning of electrical contact, therefore enhancing the power and efficiency of high-power diode lasers. For example, laser diode with longitudinally flared waveguide was fabricated to reduce the longitudinal inhomogeneity of the optical field and consequently reduce the LSHB effect [7,8]. An alternative approach is to pattern electrical contact longitudinally (non-uniform current injection) without affecting the lateral gain or optical modal distribution.…”

Section: Lshb Mitigation For Power Improvementmentioning

confidence: 99%

“…Figure 6(a) shows several profiles of such tapered waveguide designs, compared with a straight waveguide. Different from the designs demonstrated in [7,8], we set the areas of the tapered waveguides to be the same as that of the straight waveguide, which, in this case, has a 150 μm stripe width for nLIGHT's 1470 nm diode lasers. This is to maintain the same threshold current for the different designs, as well as maintaining similar thermal resistance (to the first order), so that thermal performance differences between devices can be ruled out as origin for power performance enhancement.…”

Section: Lshb Mitigation For Power Improvementmentioning

confidence: 99%

“…The longitudinal inhomogeneity of photon and carrier density is believed to lead to output decrease due to gain saturation at high injection current [3,4,5], although some authors argued that it is an small effect [6]. Experimentally, a slightly flared laser with longitudinally varying emitter width was designed with the aim of reducing LSHB and improvement of peak output power [7,8]. Further study is however required to understand the impact of LSHB to power efficiency and its implication in laser design optimization to achieve higher peak powers.…”

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Performance limitation and mitigation of longitudinal spatial hole burning in high-power diode lasers

et al. 2012

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Facets of high-power broad area diode lasers are typically coated with one high-reflecting and one partially reflecting layer to improve slope efficiency and maximize output power. The typical cavity lengths of commercial devices have also been progressively increasing, mainly to reduce temperature rise at the active region and improve laser performance and reliability. The asymmetric reflectivities and long cavity length, however, result in a highly inhomogeneous longitudinal profile of the photon density, which induces a spatially non-uniform carrier distribution, so-called longitudinal spatial hole burning (LSHB). A more uniform longitudinal photon and carrier distribution is believed to improve the overall gain of the cavity and reduce gain saturation, although further study is required to understand the impact of LSHB to power efficiency and its implication in laser design optimization to achieve higher peak powers. We present a phenomenological model that incorporates LSHB to describe longitudinal photon and carrier density inhomogeneity, as well as light-current characteristics of a diode laser. The impact of LSHB on the power efficiency is demonstrated through numerical calculation and can be significant under high-power operations. This presents new guidelines for high-power diode laser designs, in which LSHB imposes limits on reducing facet reflectivity and/or increasing cavity length, beyond which performance deteriorates. Alternatively, effects of LSHB can be mitigated through longitudinal patterning of the waveguide or contact to achieve high-power and high-efficiency diode lasers. We propose specially designed longitudinal patterning of electrical contact to mitigate LSHB. Ongoing device implementation will be used to demonstrate performance benefits.Keywords: longitudinal spatial hole burning, high-power diode lasers, tapered waveguide MOTIVATIONThe facets of high-power broad area laser diodes are typically coated with one high-reflecting (HR) and one partially reflecting (PR) layer to improve slope efficiency and maximize output power. On the other hand, the cavity length of high-power laser diodes has been getting progressively longer, mainly to reduce thermal resistance between the chip and heatsink, which mitigates temperature rise at the active region and improves diode performance and reliability. Both the asymmetric reflectivities and long cavity length, however, result in a highly inhomogeneous longitudinal profile of the photon density, which induces a spatially non-uniform carrier distribution within the laser cavity. Such spatial inhomogeneity, named longitudinal spatial hole burning (LSHB), has been studied theoretically [1] and measured experimentally [2,3]. For example, the longitudinal spatial inhomogeneity of carrier distribution has been measured using spontaneous emission through the n-side window [2] and from the side [3] of high-power laser diodes, where a higher carrier density is observed close to the HR than that to the PR facet for above-the-threshold current. The longitudin...

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Section: Lshb Mitigation For Power Improvementmentioning

confidence: 99%

Section: Lshb Mitigation For Power Improvementmentioning

confidence: 99%