A Performance Comparison Between Quantum Dash and Quantum Well Fabry-Pérot Lasers

Abstract

We directly compare the performance of 1.55 µm Fabry-Pérot lasers using quantum well (QW) and quantum dash gain regions. Other than the gain medium the designs were identical, grown in the same growth system, and processed at the same time. The static laser performance (light-current and spectral) were similar for both gain materials but the intensity and phase noise characteristics of the dash based lasers were significantly better. This was attributed to the self mode-locking of the dash lasers that was not observed for the QW lasers. This reduction in noise allowed individual lasing lines from the Fabry-Pérot dash lasers to be used for data transmission using high order modulation schemes, with quadrature phaseshift keying (QPSK) demonstrated at a symbol rate of 32 GBaud. This performance could not be achieved using the equivalent QW based laser.

Frequency multiplexing in millimeter-wave over fiber fronthaul transmission links with an InAs/InP quantum dash mode-locked laser

“…However, with the help of RoF and optical heterodyne detection, the intermedia frequency (IF) signal signal can be generated at conventional sub-6GHz bands and upconverted optically at the receiver by heterodyne detection [3][4][5][6]. The major challenge of heterodyne detection is the generation of multi-wavelength optical carriers, which should be stable and highly coherent [6], [7]. Conventionally, the multi-wavelength optical carriers are generated by modulator [8], nonlinearity [9], or quantum well (QW) mode locked laser (MLL) [7].…”

“…The major challenge of heterodyne detection is the generation of multi-wavelength optical carriers, which should be stable and highly coherent [6], [7]. Conventionally, the multi-wavelength optical carriers are generated by modulator [8], nonlinearity [9], or quantum well (QW) mode locked laser (MLL) [7]. For first two methods, extra modulators and non-linear devices are required after a CW laser, which will significantly increase the complexity of the system [8], [9].…”

“…For first two methods, extra modulators and non-linear devices are required after a CW laser, which will significantly increase the complexity of the system [8], [9]. If a QW-MLL is used as laser source, it can generate multiple optical carriers simultaneously and solely, but it is not stable and coherent enough hence the phase noise after heterodyne detection is high [7]. In this paper, InAs/InP quantum dash (QD) MLL is adopted as laser source It possesses the capability to generate tens of highly coherent optical carriers, known as comb lines, the RF linewidth after heterodyne detection can be as low as 15 kHz [10].…”

Height distributions of uncapped InAs/InGaAsP/InP quantum dashes and their effect on emission wavelengths

“…By capping these nanoparticles after self-assembly, quantum dash or dot arrays can be grown in stacks. These stacked arrays offer favourable properties as gain media in lasers compared to quantum wells when used to create multiwavelength lasers for high speed telecommunications [3]. Self-assembled InAs quantum dashes grown on InP substrates can be designed to emit at 1550 nm, in the C-band transmission band of optical fiber.…”