D. C. Larrabee

Gain, loss, and internal efficiency in interband cascade lasers emitting at λ=3.6–4.1μm

We employ a cavity-length study to determine the temperature variation of the internal loss and gain per unit current density in a ten-stage interband cascade laser that operated cw up to 269K with an emission wavelength of 4.05μm. The characteristic temperature for the gain per unit current density is 39K, which is slightly lower than T0 of the threshold current and is consistent with dominance by Auger recombination. The internal loss for the 150-μm-wide mesa devices increased from 11cm−1 at 78Kto28cm−1 at 275K.

Interband cascade laser operating cw to 257K at λ=3.7μm

A five-stage interband cascade laser with 12μm ridge width and Au electroplating for improved epitaxial-side-up heat sinking operates cw to a maximum temperature of 257K, where the emission wavelength is 3.7μm. The device emits 100mW/facet for cw operation at 80K, 54mW at 200K, and 10mW at 250K. The beam quality is within twice the diffraction limit for injection currents up to 14 times the lasing threshold at 120K.

Broad-stripe, single-mode, mid-IR interband cascade laser with photonic-crystal distributed-feedback grating

We have demonstrated an electrically pumped photonic-crystal distributed-feedback laser with an interband cascade active region emitting at 3.3μm. At 78K, the stripe of width 400μm emits up to 67mW of cw power into a single spectral mode with side-mode suppression ratio ≈27dB. The full width at half maximum of the far-field divergence angle is ≈0.5°, which combined with the near-field profile yields an effective M2 of 1.7–2.0.

High-temperature interband cascade lasers emitting at λ=3.6–4.3μm

The authors report the operating characteristics of ten-stage interband cascade lasers from two wafers with room-temperature wavelengths of 4.1 and 4.3μm. For 150-μm-wide stripes, the threshold current densities are as low as 4.8A∕cm2 at 78K (cw) and 1.15kA∕cm2 at room temperature (pulsed). At 78K, the cw wall-plug efficiency for an 11-μm-wide ridge with 0.5-mm-long cavity and coated facets is 27%, while a 3-mm-long cavity emits a maximum cw power of 200mW. Devices from the two wafers have maximum cw operating temperatures of 261K (λ≈4.0μm) and 243K (λ≈4.2μm).

Enhanced performance of organic light-emitting diodes using two-dimensional zinc sulfide photonic crystals

The light extraction efficiency of an organic light-emitting diode (OLED) was significantly enhanced upon incorporating a photonic-crystal (PC) pattern consisting of ZnS pillars residing on top of the transparent anode-glass substrate. The luminance efficiency of the PC-OLED is enhanced by a factor of 2.1 to 2.4 depending on the periodicity of the PC structure, when compared to that of a control OLED operating under the same conditions.

Mid-infrared interband cascade lasers operating CW at thermoelectric-cooler temperatures

Mid-infrared interband cascade lasers with 11-mum-wide ridge width and Au electroplating operated cw to 288 K, where the emission wavelength was 4.1 mum. Another device emitted at 5.1 mum and operated cw to 229 K.

Robust single-mode emission from mid-IR photonic crystal interband cascade lasers

Electrically-pumped photonic-crystal distributed-feedback lasers with interband-cascade active regions operating in single spectral mode at 3.3 μm are demonstrated. At 78 K, a stripe of width 400 μm emits up to 67 mW of cw power into a single spectral mode with side-mode suppression ratio ≈ 27 dB. The full-width at half-maximum of the farfield divergence angle is ≈ 0.5°, which combined with the near-field profile yields an effective M2 of 1.7-2.0.

High-Performance Fabry-Perot and Distributed-Feedback Interband Cascade Lasers

We review recent NRL progress in the development of interband cascade lasers for the 3–4 μm spectral range. The maximum cw operating temperature has reached 269 K, and the pulsed threshold current density at room temperature is as low as 790 A/cm2. The internal loss in a broad-area laser (λ = 3.5–3.9 μm) varies from 11 cm−1 at 78 K to 28 cm−1 at 275 K, and most of the increase in threshold with temperature (T 0 ≈ 40 K) is due to a shorter non-radiative lifetime. We also discuss a distributed-feedback laser that demonstrated stable single-mode operation at all temperatures between 78 and 160 K, with a side-mode suppression ratio ≥25 dB.

Single-chip Interband Cascade DFB laser with Extended Tuning Range

We report the operation of an interband cascade-based DFB laser in the mid-IR. The device operates single-mode from 78 to 160 K, with up to 10 nm of current tuning and quasi-continuous tuning of 26 nm by also varying temperature.

High-temperature CW mid-infrared interband cascade lasers

The ICL performance has improved dramatically in recent years, with maximum cw operating temperatures of 264 and 269 K being reported by the groups at JPL and NRL, respectively. Narrow ridges were quite recently fabricated from the latest ICL wafers, using epitaxial-side-up mounting topped by Au-electroplating to enhance the heat removal. The longer-wavelength ICL operated cw to 229 K, which is considerably higher than for any earlier interband laser emitting at such long. The ridge was generated over 80 mW of cw power at 78 K, where the lasing threshold was only 4.7 A/cm.