Abstract
It is shown theoretically that a GaAs/AlGaAs laser diode design using an asymmetric waveguide structure and a bulk active layer (AL), located close to the p-cladding, can provide high output power in a single, broad transverse mode for short-wavelength (<0.9 μm, matching the spectral range of high efficiency of silicon photodetectors) pulsed emission in the nanosecond pulse duration region, typically <<100 ns. The dependences of the laser performance on the thickness of the AL and the cavity length are analysed. It is shown that the relatively thick bulk AL allows the of short cavity lengths (<1 mm), for achieving high pulsed power while maintaining a relatively low series resistance and a narrow far field.
Highlights
| INTRODUCTIONHigh power broad area diode lasers operating in the quasi‐ continuous‐wave (quasi‐CW) pulsed regime (with pump pulses long enough to achieve steady state from the laser dynamics point of view yet short enough to not cause substantial current heating, in practice corresponding to the nanosecond region) are important components of Lidars [1] as well as for a number of other applications
High power broad area diode lasers operating in the quasi‐ continuous‐wave pulsed regime are important components of Lidars [1] as well as for a number of other applications
The other involves working at shorter wavelengths and can be further subdivided in two spectral regions: λ ∼ 0.9–1.1 μm [10,11,12,13] and λ < 0.9 μm, used [14, 15] for the case of nanosecond pump pulses resulting in picosecond pulse emission under gain‐switched operation
Summary
High power broad area diode lasers operating in the quasi‐ continuous‐wave (quasi‐CW) pulsed regime (with pump pulses long enough to achieve steady state from the laser dynamics point of view yet short enough to not cause substantial current heating, in practice corresponding to the nanosecond region) are important components of Lidars [1] as well as for a number of other applications. The other involves working at shorter wavelengths and can be further subdivided in two spectral regions: λ ∼ 0.9–1.1 μm [10,11,12,13] and λ < 0.9 μm, used [14, 15] for the case of nanosecond pump pulses resulting in picosecond pulse emission under gain‐switched operation The latter spectral range makes use of the efficient and reliable GaAs/AlGaAs emitters and, crucially, the relatively mature technology of Silicon Single‐Photon Avalanche Photodetectors [16] which have a high sensitivity at the operating wavelengths below 900 nm. The design of high‐power laser structures in both InGaAsP/InP and (InGaAs)GaAs/AlGaAs material systems used almost exclusively thin active layers (ALs), including 1–3 Quantum Wells (QWs) In the latter case, this was at least because the research largely concentrated on the λ = 0.9 −1.1 μm range, where the use of Indium containing components is necessary and growing thick ALs is impossible due to lattice mismatch induced strain.
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