High-performance p-B-n infrared photodetectors based on In0.53Ga0.47As/Ga0.51As0.49Sb type-II superlattices with an Al0.85Ga0.15AsSb barrier on an InP substrate have been demonstrated. These photodetectors exhibit 50% and 100% cutoff wavelengths of ∼2.1 μm and ∼2.6 μm, respectively. At a bias voltage of −100 mV bias voltage, the device exhibits a peak responsivity of 0.618 A/W at 2.1 μm, corresponding to a quantum efficiency of 36.5%. The device exhibits a saturated dark current shot noise limited specific detectivity (D*) of 4.12 × 1010 cm·Hz1/2/W (at a peak responsivity of 2.1 μm) under −100 mV applied bias at 300 K.

The device characteristics of semiconductor quantum dot lasers have been improved with progress in active layer structures. Self-assembly formed InAs quantum dots grown on GaAs had been intensively promoted in order to achieve quantum dot lasers with superior device performances. In the process of growing high-density InAs/GaAs quantum dots, bimodal size occurs due to large mismatch and other factors. The bimodal size in the InAs/GaAs quantum dot system is eliminated by the method of high-temperature annealing and optimized the in situ annealing temperature. The annealing temperature is taken as the key optimization parameters, and the optimal annealing temperature of 680 °C was obtained. In this process, quantum dot growth temperature, InAs deposition, and arsenic (As) pressure are optimized to improve quantum dot quality and emission wavelength. A 1.3-μm high-performance F-P quantum dot laser with a threshold current density of 110 A/cm2 was demonstrated.

Uniform arrays of three shapes ($gauss$, $hat$, and $peak$) of GaAs microlenses (MLs) by wet-etching are demonstrated, ∼200 nm spatial isolation of epitaxial single QDs embedded ($\lambda$: 890–990 nm) and broadband ($\Delta \lambda \sim 80$ nm) enhancement of their quantum light extraction are obtained, which is also suitable for telecom-band epitaxial QDs. Combined with the bottom distributed Bragg reflector, the $hat$-shaped ML forms a cavity and achieves the best enhancement: extraction efficiency of 26%, Purcell factor of 2 and single-photon count rate of $7\times {10}^6$ counts per second at the first lens; while the $gauss$-shaped ML shows a broader band (e.g., longer $\lambda$) enhancement. In the MLs, single QDs with featured exciton emissions are observed, whose time correlations prove single-photon emission with multi-photon probability $g^{\left(2\right)}\left(0\right)=0.02$; some QDs show both biexciton $XX$ and exciton X emissions and exhibit a perfect cascade feature. This work could pave a step towards a scalable array of QD single-photon sources and the application of QD photon-pair emission for entanglement experiments.

We present a extend short-wave infrared photodetector featuring a p-doped InGaAs/GaAsSb type-II superlattices (T2SL) absorber encapsulated by a pair of electron-blocking and hole-blocking barriers. Each barrier uses different InGaAs/GaAsSb T2SL design lattice matched to InP substrate. The single element device exhibits 100% cut off wavelength of 2.32 μm at 300K. It achieves saturated QE values of 50.7% at 1.6 μm under front-side illumination without any anti-reflection coating. At 300K, the photodetector exhibits a dark current density of 5.38×10-3 A/cm2 under -20 mV applied bias, providing a specific detectivity of 8.18×109 Jones. Clear infrared imaging using f/2 optics and an integration time of 12 ms was obtained at 300 K by a 640×512 focal plane array using the same structure design.

GaSb-based single-transverse-mode narrow ridge waveguide (RW) lasers with high power and simultaneous good beam quality have broad application prospects in the mid-infrared wavelength region. Yet its design and formation have not been investigated systematically, while the beam characteristics that affect their suitability for specific applications remain rarely analyzed and optimized. The present work addresses these issues by theoretically establishing a waveguide parameter domain that generalizes the overall possible combinations of ridge widths and etch depths that support single-transverse-mode operation for GaSb-based RW lasers. These results are applied to develop two distinct and representative waveguide designs derived from two proposed major optimization routes of model gain expansion and index-guiding enhancement. The designs were evaluated experimentally based on prototype 1-mm cavity-length RW lasers in the 1950 nm wavelength range, which were fabricated with waveguides having perpendicular ridge and smooth side-walls realized through optimized dry etching conditions. The model gain expanded RW laser design with a relatively shallow-etched (i.e., 1.55 $$\upmu$$μ m) and wide ridge (i.e., 7 $$\upmu$$μ m) yielded the highest single-transverse-mode power to date of 258 mW with a narrow lateral divergence angle of 11.1 $$^\circ$$∘ full width at half maximum at 800 mA under room-temperature continuous-wave operation, which offers promising prospects in pumping and coupling applications. Meanwhile, the index-guiding enhanced RW laser design with a relatively deeply etched (i.e., 2.05 $$\upmu$$μ m) and narrow ridge (i.e., 4 $$\upmu$$μ m) provided a highly stable and nearly astigmatism-free fundamental mode emission with an excellent beam quality of M $$^2$$2 factor around 1.5 over the entire operating current range, which is preferable for seeding external cavity applications and complex optical systems.

We proposed a precise calibration process of Al _0.9Ga_0.1As/GaAs DBR micropillar cavity to match the single InAs/GaAs quantum dot (QD) exciton emission and achieve cavity mode resonance and a great enhancement of QD photoluminescence (PL) intensity. Light-matter interaction of single QD in DBR micropillar cavity (Q ∼ 3800) under weak coupling regime was investigated by temperature-tuned PL spectra; a pronounced enhancement (14.6-fold) of QD exciton emission was observed on resonance. The second-order autocorrelation measurement shows g⁽²⁾(0)=0.070, and the estimated net count rate before the first objective lens reaches 1.6×10⁷ counts/s under continuous wave excitation, indicating highly pure single-photon emission at high count rates.