Demonstration of transverse-magnetic dominant gain in quantum dot semiconductor optical amplifiers

Abstract

We demonstrated transverse-magnetic (TM)-mode dominated gain at the 1.5μm wavelength in semiconductor optical amplifiers (SOAs) with columnar quantum dots (QDs). We show that we can control the polarization dependence of optical gain in QD-SOAs by changing the height and tensile-strained barrier of columnar QDs. The TM mode gain is 17.3dB and a gain of over 10dB was attained over a wide wavelength range of 200nm. The saturation output power is 19.5dBm at 1.55μm.

Vertical stacking of InAs quantum dots for polarization-insensitive semiconductor optical amplifiers

“…Verticallyaligned QDs separated by GaAs intermediate layers are clearly seen. This feature is obviously different from columnar QDs in which stacked InAs layers form large QDs as a whole [2,3,4]. The wavelength-integrated EL intensities are shown in figure 2.…”

“…In our previous works, we proposed artificial control of the photoluminescence (PL) polarization [2] and optical gain [3] by using closely stacked QDs called columnar QDs. Furthermore, recently, polarization-insensitive optical gain in the 1.55-mm band has been demonstrated using InP-based columnar QD-SOA [4]. On the other hand, closely stacked QDs with intermediate layers have been considered as a candidate for realizing polarization-insensitive SOA [5,6].…”

Tuning of polarization sensitivity in closely stacked trilayer InAs/GaAs quantum dots induced by overgrowth dynamics

“…In this context, one relevant physical example are closely stacked quantum dots, either consisting of QD layers separated by a thin GaAs spacer [3][4][5], or without using any GaAs spacer (also known as columnar QDs [6] or quantum posts [7]). In these kinds of nanostructures, the strong compressive biaxial strain component at the center of the typical flat shape dot can be reduced to zero or towards tensile values by increasing the stack height (adding QD layers), thus providing the optical polarization insensitivity desirable for relevant technological applications such as semiconductor optical amplifiers for high speed communication networks [8][9][10]. Such a requirement cannot be fulfilled by standard flat dome-shape QDs, where the biaxial compressive strain induces the valence band splitting into the heavy hole and the light hole states, thus providing strongly TE polarised optical transition [11].…”

Radiative Recombination Mechanisms of Large InAs/GaAs Quantum Dots

“…Important examples are the application of QDs as active media in light emitters, as light-emitting diodes (LEDs) and lasers for telecommunication purposes, and optical amplifiers [1][2][3][4]. Although, more recently, the research in the field of QD materials is also committed to the exploration of the peculiar electronic properties of these systems as, e.g., the use of quantum dots in high-performance photodetectors or DNA nanosensors for medical diagnosis and biomolecular investigations [5,6], as well as, in the field of quantum cryptography and quantum computing using single-QD devices [7][8][9][10].…”