A study of internal absorption in Zn(Cd)Se/ZnMgSSe semiconductor lasers

Abstract

Based on two different experiments and an optical field calculation, we show that the free-carrier absorption αfc in Zn(Cd)Se/ZnMgSSe semiconductor lasers is about 4 cm−1 and that it is smaller than that of GaAs/AlGaAs semiconductor lasers. We have measured the dependence of the L-I characteristics on the cavity length of double heterostructure (DH) lasers under photopumped operation and of single quantum well-separate confinement heterostructure (SQW-SCH) lasers under current-injected operation. For the DH laser, the total absorption coefficient αi and β×J0 product (β is a gain constant, and J0 is the nominal current density that makes the gain equal to zero) are estimated to be 4.2 cm−1 and 8.6×10 cm−1, respectively. For the SQW-SCH laser, αi, β, and J0 are estimated to be 21 cm−1, 4.23×10−3 cm×μm/A, and 1.9×10−3 A/(cm2×μm), respectively. By calculating the optical fields of these lasers, we have estimated that the absorption in a GaAs substrate is 16.53 cm−1 in the SQW-SCH laser and that it is negligible in the DH laser. We have shown that the large loss in the SQW-SCH laser is caused by both αfc and the absorption in the substrate and that αi in the DH laser is caused only by free carrier absorption.

Arrays of Two-Dimensional Islands Formed by Submonolayer Insertions: Growth, Properties, Devices

“…Assuming that radiative and nonradiative losses are also significant, the actual internal losses in this structure must be much less than 20 cm --1 . The internal losses close to the estimated value are compatible with the internal losses in the structure with external optical confinement provided by thick wider band-gap layers with smaller refractive index [75].…”

“…Figure 13 demonstrates the dependence of the threshold excitation density (P th ) on the stripe length (L) at 16 K for the structure with stacked CdSe/ZnMgSSe SML QDs. As it was shown in [75] P th can be written as…”

Optically pumped lasing of GaN/AlGaN structures grown along a non‐polar crystallographic direction

“…The shift of the laser emissions toward higher energies with a decreasing thickness of the wells in the active region strongly confirms that laser emission occurred at the active region of the laser structure, and not in the bulk material of the substrate. Through the use of different cavity lengths in our experiments, we were able to determine the optical losses in the first laser structure [5]. This may be obtained by measuring the differential efficiency as a function of the inverse cavity length (Fig.…”

Optically Pumped Laser Action on Nitride Based Separate Confinement Heterostructures Grown along the (11¯20) Crystallographic Direction

“…The higher threshold for laser 2 in comparison with laser 1 is due to the competition between all these effects. In our experiments, by using different cavity lengths we were able to determine the optical losses in the first laser structure [11]. This may be achieved by measuring the differential efficiency as a function of the inverse cavity length (Fig.…”