Burn-in mechanism of 450nm InGaN ridge laser test structures

Abstract

We investigated the short term stability of the optical output power of 450nm InGaN test lasers. The short term degradation strongly depended on ridge width. It was mainly caused by an increase in threshold current. From measurements of subthreshold wave-length blueshift, carrier lifetime, and output power, we found a decrease in carrier density after 15h of aging. We show a direct correlation of the short term aging with current spreading effects.

Ridge waveguide InGaN/GaN quantum dot edge emitting visible lasers

“…Theoretical calculations [10] have also shown a much reduced polarization field present in the InGaN QDs. Assuming an effective height for QDs, from the peak emission shift, a polarization field of ~80 kV/cm is calculated for the QDs which matches well with the theory, and is much lower compared with similar quantum well devices (~2.1 MV/cm) [15,16]. A near field image from a 4 µm wide ridge waveguide laser, with a cavity length of 1.2 mm, is shown as a contour plot in Fig.…”

Gain analysis of blue nitride-based lasers by small signal modulation

“…Further details of the fit procedure can be found in previous works. 5 Pouring these results in Eq. ͑6͒, a gain coefficient of g 0 = 7680 cm −1 is designated for our blue lasers.…”

“…Information about growth conditions and epitaxial and ridge design of the laser can be found in previous publications. 5 The response is nearly constant for small frequencies and drops when the small signal modulation becomes too fast. The cut off is shifted toward higher frequen- cies due to higher photon densities in the cavity when the dc current is increased.…”

Continuous-wave operation and differential gain of InGaN/GaN quantum dot ridge waveguide lasers (λ = 420 nm) on c-plane GaN substrate

“…The measured blue shift is only 4.4 nm, which is an order of magnitude smaller than that measured in comparable InGaN/GaN quantum well devices. 8,15 It may also be noted that there is no change of emission wavelength beyond threshold, which is a desirable attribute. A piezoelectric field of 80 kV/cm in the InGaN QDs is estimated from the measured wavelength shift, compared to a value $2.1 MV/cm reported for equivalent InGaN/GaN quantum wells.…”