Optical Gain and Absorption of Quantum Dots Measured Using an Alternative Segmented Contact Method

Simultaneous quantum dash-well emission in a chirped dash-in-well superluminescent diode with spectral bandwidth >700 nm

“…A 50 μm oxide-strip broad area SLD was fabricated using the standard laser fabrication process and the partial suppression of Fabry-Perot resonances in the optical path is achieved via the integration of a photon absorber (PA) section to a 1.0 mm long pump (gain section) section [5,6]. For absorption measurements, 3 μm × 1000 μm ridge-waveguide multisection devices were fabricated with 10 μm isolation between each section [14]. The nonfacet-coated SLD devices were tested on a brass heat sink using a thermoelectric cooler operated at 20°C, under CW operation, by pumping only the gain section while the PA section was left unpumped.…”

Monolithic passively mode-locked lasers using quantum-dot or quantum-well materials grown on GaAs substrates

“…Devices were fabricated according to standard multi-section device processing 17 . After the first lithography with the ridgewaveguide-mask, the sample was etched to form 3-µm wide, 1.8-µm deep ridges by inductively coupled plasma (ICP) etching in BCl 3 .…”

“…Since the GaInNAsSb is relatively immature QW laser material system, the net modal gain as shown in Figure 10(a) and loss spectra of the GaInNAsSb active region were obtained with the improved segmented contact method 17 to assess the material's suitability for mode-locked devices. The net modal gain saturates at about 15 cm -1 and the internal loss is about 4 cm -1 , which are relatively modest and comparable to the QD active region values due to the use of a single QW and the low density of states from high compressive strain.…”

Gain spectrum measurement using the segmented contact method with an integrated optical amplifier

“…However, Xin et al commented on the possible use of the mode-filter as an amplifier. 10 GaAs based quantum dot (QD) devices are of interest due to their low cost, temperature insensitive threshold current density 11,12 and their current applications in biomedical imaging, 13 mode-locking applications, 14 and optical communications. 15 However, the gain spectrum in QD materials is complicated by inhomogeneous and homogeneous broadening, 16 strong state-filling effects, 17 and by free carrier effects.…”

“…In this paper, we report on the use of the front sections of a QD multisection device to act as an integrated amplifier and mode filter as proposed by Xin et al 10 Xin et al showed that using a segmented-contact device, the waveguide itself could be used as a mode filter, which is required for the removal of the unguided spontaneous emission. 9 They also proposed that when driven into gain, this amplifier/mode filter may be beneficial in the measurement of small signals.…”