Mid-IR quantum dot cascade VCSEL: feasibility study and feature extraction

Abstract

Quantum cascade lasers with quantum dot (QD) active regions have been developed to overcome the drawbacks of quantum-well-based cascade lasers. Low threshold current and enhanced bandwidth characteristics of QD lasers can be combined with promising energy-efficient features of vertical cavity surface emitting lasers (VCSELs) through introducing the novel, to the best of our knowledge, concept of a QD cascade VCSEL (QDC-VCSEL). Design steps and predicted features of a QDC-VCSEL operating at 4.5 µm wavelength are discussed in this paper, where the cavity and active region are optimized for TE mode using a high contrast grating design. Laser characteristics are investigated by developing rate equations for the cascade scheme. Threshold and L-I characteristics are obtained at different temperatures. Also, the dependency of threshold current, slope efficiency, and modulation bandwidth on design parameters, mainly the carrier tunneling time, is studied. Results exhibit output peak powers of ∼ 2 and ∼ 0.5 m W at 150 and 273 K, respectively. In addition, threshold current increment and modulation bandwidth reduction are observed with the increase in tunneling time.

Polarization-independent high contrast grating 1300 nm dot-in-a-well InAs quantum-dot VCSEL

“…where R , t R b are the top and bottom mirrors' reflectivity, respectively. Effective cavity length can be calculated by [22,28]:…”

“…In semiconductor lasers, the primary heat source is the non-radiative recombination and free-carrier absorption of the coherent radiation in the active region [6,22]. Also, the joule heating effect is another less dominant heat source, which could be ignored since the upper DBRs were replaced with HCG and a negligible Joule heating effect took place.…”

“…It also allows us to design stable polarization-dependent or independent devices [14][15][16]. So far, HCG VCSELs with lasing wavelengths of 808 nm, 850 nm, 980 nm, 1060 nm, 1320 nm, 1550 nm, and 4500 nm have been reported [12,[17][18][19][20][21][22]. A summary of some of the improvements is as follows: Active region cooling by about 7 K for low injection current densities [17], wavelength tuning speed of 150 ns which is 40-50 times faster compared with DBR tunable VCSEL [12], TM-polarized emission [18], tunable single-mode operation [18], single-mode emission for large aperture size of 11 μm [20], and TE-polarized low temperature-sensitive operation [22].…”

Effect of dielectric mismatch on impurity binding energy, photoionization cross-section and stark shift of CdS/ZnSe core shell spherical quantum dots

“…For example, in immunoassays, microarrays, fluorescent imaging applications, quenching sensors and barcoding systems [5,6], QD probes can be used as biosensors in nanomedicine to target and detect cancer cells [7]. In addition, some of the uses of quantum dots can be listed as energy storage [8][9][10], solar cell energy conversion [11], photodetector [12], quantum computing [13], quantum dot vertical cavity surface emitting lasers (VCSELs) [14]. It has also been shown to provide remarkable advantages in the design of many optoelectronic devices, such as the intersublevel photodetector (QDIP) [15].…”