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Thermal Effects and Small Signal Modulation of 1.3- μ m InAs/GaAs Self-Assembled Quantum-Dot Lasers

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ABSTRACT

We investigate the influence of thermal effects on the high-speed performance of 1.3-μm InAs/GaAs quantum-dot lasers in a wide temperature range (5–50°C). Ridge waveguide devices with 1.1 mm cavity length exhibit small signal modulation bandwidths of 7.51 GHz at 5°C and 3.98 GHz at 50°C. Temperature-dependent K-factor, differential gain, and gain compression factor are studied. While the intrinsic damping-limited modulation bandwidth is as high as 23 GHz, the actual modulation bandwidth is limited by carrier thermalization under continuous wave operation. Saturation of the resonance frequency was found to be the result of thermal reduction in the differential gain, which may originate from carrier thermalization.

No MeSH data available.


The lasing spectrum from the InAs/InGaAs QD laser (4 × 1,100 μm2) with injection current of 100 mA at RT.
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Figure 2: The lasing spectrum from the InAs/InGaAs QD laser (4 × 1,100 μm2) with injection current of 100 mA at RT.

Mentions: The measured CW Power-Current performance of a device with cavity length of 1.1 mm shows that the threshold current (Ith) and slope efficiency are 55 mA and 0.27 W/A at room temperature, respectively. Maximum output power of 96 mW occurred at injection current of 395 mA. Figure 2 shows the lasing spectrum of the laser device under injection current of 100 mA at RT for verification. The lasing wavelength is centered at 1,306.5 nm. Furthermore, no lasing at excited state was observed. Characteristic temperature To is around 41 K from 5 to 50°C. The small signal modulation response under different injection current levels is shown in Figure 3. At room temperature, the highest bandwidth of 6.1 GHz was obtained at injection current level of 390 mA. For injection current more than 395 mA, the resonance frequency fr decreases with increasing injection current. This is because, there are two competing factors affecting the resonance frequency: (1) increase in resonance frequency with injection current and (2) decrease in resonance frequency due to internal heating. Therefore, when injection current increases higher than 395 mA, the internal heating resulted from the increased current becomes dominant and leads to the decrease in resonance frequency. The small signal modulation response was further fitted into a transfer function that accounts for the intrinsic response of the laser as well as the extrinsic effects [16]:


Thermal Effects and Small Signal Modulation of 1.3- μ m InAs/GaAs Self-Assembled Quantum-Dot Lasers
The lasing spectrum from the InAs/InGaAs QD laser (4 × 1,100 μm2) with injection current of 100 mA at RT.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211460&req=5

Figure 2: The lasing spectrum from the InAs/InGaAs QD laser (4 × 1,100 μm2) with injection current of 100 mA at RT.
Mentions: The measured CW Power-Current performance of a device with cavity length of 1.1 mm shows that the threshold current (Ith) and slope efficiency are 55 mA and 0.27 W/A at room temperature, respectively. Maximum output power of 96 mW occurred at injection current of 395 mA. Figure 2 shows the lasing spectrum of the laser device under injection current of 100 mA at RT for verification. The lasing wavelength is centered at 1,306.5 nm. Furthermore, no lasing at excited state was observed. Characteristic temperature To is around 41 K from 5 to 50°C. The small signal modulation response under different injection current levels is shown in Figure 3. At room temperature, the highest bandwidth of 6.1 GHz was obtained at injection current level of 390 mA. For injection current more than 395 mA, the resonance frequency fr decreases with increasing injection current. This is because, there are two competing factors affecting the resonance frequency: (1) increase in resonance frequency with injection current and (2) decrease in resonance frequency due to internal heating. Therefore, when injection current increases higher than 395 mA, the internal heating resulted from the increased current becomes dominant and leads to the decrease in resonance frequency. The small signal modulation response was further fitted into a transfer function that accounts for the intrinsic response of the laser as well as the extrinsic effects [16]:

View Article: PubMed Central - HTML - PubMed

ABSTRACT

We investigate the influence of thermal effects on the high-speed performance of 1.3-μm InAs/GaAs quantum-dot lasers in a wide temperature range (5–50°C). Ridge waveguide devices with 1.1 mm cavity length exhibit small signal modulation bandwidths of 7.51 GHz at 5°C and 3.98 GHz at 50°C. Temperature-dependent K-factor, differential gain, and gain compression factor are studied. While the intrinsic damping-limited modulation bandwidth is as high as 23 GHz, the actual modulation bandwidth is limited by carrier thermalization under continuous wave operation. Saturation of the resonance frequency was found to be the result of thermal reduction in the differential gain, which may originate from carrier thermalization.

No MeSH data available.