Effect of the waveguide layer thickness on output characteristics of semiconductor lasers with emission wavelength from 1500 to 1600 nm

High Power $1.5\mu$ m Pulsed Laser Diode With Asymmetric Waveguide and Active Layer Nearp-cladding

“…2 is nearly linear at low currents and shows some saturation tendency at currents high above threshold (at I > 30 A). The total overall power achieved (≈18 W at 80 A from a laser with a stripe width of 90 μm) compares favorably with published results [2], [4], [5].…”

“…This is possible because of the strong doping of the p-cladding, which in turn is made possible by its small overlap with the mode, as discussed above. Note also that, as mentioned above, this uniformly highly doped p-cladding gives also the added advantage over the graded-doping structures of [3], [5] by ensuring lower series resistance, and also helps prevent electron leakage from the OCL to the p-cladding. Secondly, the current structure has a somewhat narrower OCL than the one studied in [20] (1.8 μm instead of 2.8 μm) and so, to maintain the mode localization in the OCL, has The narrower OCL translates into a far field somewhat broader than that predicted for the structure of [20], with a full width at half maximum of 24 • instead of 17 • .…”

“…used differ substantially. Using lasers with ultra-narrow, single transverse mode symmetric waveguide structures ( [2], [3], see also [4], [5]), output power values as high as ≈16 W at wavelengths of 1500 to 1600 nm have been obtained, at pump currents of 80 A, from samples with a length of 2 mm and a stripe width of 95 μm [2]. The advantage of such structures is that they effectively combat the nonlinear optical losses at high currents.…”

“…The penalty is that in such waveguides, it is difficult to avoid high built-in optical losses caused by the substantial (almost 50%) penetration of the optical field into the p-cladding, where a large free hole density is present even at low currents. It is possible to reduce (but not eliminate) this effect by tailoring the doping in the claddings [3]- [5], which however leads to an increase in the series resistance and can also substantially increase the rate of leakage of electrons from the active layer into the p-claddings [10]- [12]. Alternative designs (mostly used at shorter wavelengths) use large optical cavity (LOC) separate confinement symmetric (or nearly symmetric) waveguide structures.…”

AlGaAs/GaAs asymmetric‐waveguide, short cavity laser diode design with a bulk active layer near the p ‐cladding for high pulsed power emission

“…With regard to the spectral range of laser emission, two strategies are possible. One involves working in the eye-safe spectral range of 1300-1600 nm, allowing high output power to be used, and requiring InGaAsP/InP [2][3][4] or AlGaInAs/InP [5][6][7][8][9] based sources and photodetectors. 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.…”