Joel Jacquet

High-Power Tunable Dilute Mode DFB Laser With Low RIN and Narrow Linewidth

We have developed a 1-mm-long high-power DFB laser using an asymmetrical cladding based on the dilute waveguide technique. We have obtained about 180 mW output power at 25°C and >;30 mW at 15°C-85°C chip temperature with >;55-dB sidemode suppression ratio. This temperature range allows a 9.7-nm wavelength tunability. For high output power, the relative intensity noise is lower than -160 dB/Hz in the 0.08-40-GHz frequency range and the optical linewidth is better than 300 kHz.

High Peak Power, Narrow RF Linewidth Asymmetrical Cladding Quantum-Dash Mode-Locked Lasers

In this paper, we report the development of an asymmetrical cladding single-section InAs/InP quantum-dash mode-locked laser (MLL). The asymmetrical cladding structure allows us to decrease the internal losses and to increase the optical eigenmode mode size. We have measured continuous-wave power superior to 400 mW and RF linewidth as narrow as 300 Hz for passive modelocking. We have compressed the optical signal using the dispersion of a single-mode fiber (SMF) and we have measured the delay between groups of optical modes for different SMF lengths. With the appropriate SMF length, we have obtained a quasi-null delay. In this configuration, subpicosecond pulses with 18 W peak power have been demonstrated for 10-GHz MLL. These performances demonstrate the potential of InAs/InP MLL for frequency comb generation up to tetahertz domain and high peak power optical pulse generation.

High-Power, Low RIN 1.55-

We report the demonstration of high-power and low relative intensity noise (RIN) directly modulated distributed feedback lasers at 1.55 μm. We have developed a structure with asymmetrical cladding to reduce internal losses due to the p-doped upper cladding. We obtain an output power of 140 mW at 550 mA and an RIN below -157 dB/Hz in the 0.1-20 GHz range along with a high side-mode suppression ratio (>;55 dB). The modulation bandwidth was larger than 7 GHz. The characteristics of these lasers, namely a high electrical to optical conversion efficiency (0.340 W/A at 350 mA), low noise, high power (98 mW at 350 mA), and linearity, make them the perfect candidates for high gain, high dynamic directly modulated analog links.

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Observation of spatial hole burning reduction is reported for the first time to our knowledge on flared 1480-nm high-power InGaAsP-InP buried ridge lasers. We determined the longitudinal carrier density profile by spatially resolved spontaneous emission measurements for slightly tapered and straight active waveguides. The tapered stripe shows spatial hole burning reduction leading to 25% output power enhancement.

Directly Modulated DFB Lasers for Analog Signal Transmission

In order to achieve a high output power, high gain and high dynamic range directly modulated optical link, we have developed a high power and low noise DFB laser and a high power handling and high efficiency photodiode with specific designs. The laser exhibits high power (180 mW), high efficiency (0.4 W/A), low RIN and a 7.4 GHz modulation bandwidth. The UTC photodiode offers high efficiency (1 A/W), high saturation current (90 mA) and 15 GHz modulation bandwidth. We have realized a low loss optical link with no amplifier and no impedance matching network. We have obtained a 7.3 GHz modulation bandwidth link with a gain higher than . Third order intermodulation of the devices at various different polarization points has been investigated to deduce the optical link dynamic range. At 2.5 GHz, we have demonstrated an OIP3 of 37 dBm and a SFDR close to 120 dB · Hz2/3.

Experimental demonstration of spatial hole burning reduction leading to 1480-nm pump lasers output power improvement

Abstract A high reflectivity and polarization selective high contrast grating mirror has been designed with the use of an automated optimization algorithm. Through a precise study of the tolerance of the different lengths of the structure, the robustness with respect to the fabrication errors has been enhanced to high tolerance values between 5% and 210%. This adjustment of the dimensions of the structure leads to a 250xa0nm large bandwidth mirror well adapted for a VCSEL application at λ = 2.65 μ m and can easily be scaled for other wavelengths.

High Optical Power, High Gain and High Dynamic Range Directly Modulated Optical Link

High polarization selective Si/SiO2 mid-infrared sub-wavelength grating mirrors with large bandwidth adapted to VCSEL integration are compared. These mirrors have been automatically designed for operation at λ = 2.3 µm by an optimization algorithm which maximizes a specially defined quality factor. Several technological constraints in relation with the grating manufacturing process have been imposed within the optimization algorithm and their impact on the optical properties of the mirror have been evaluated. Furthermore, through the tolerance computation of the different dimensions of the structure, the robustness with respect to fabrication errors has been tested. Finally, it appears that the increase of the optical performances of the mirror imposes a less tolerant design with severer technological constraints resulting in a more stringent control of the manufacturing process.

Optimized Si/SiO2 high contrast grating mirror design for mid-infrared wavelength range: Robustness enhancement

A GaAs/AlOx high contrast grating structure design which exhibits a 99.5% high reflectivity for a 425 nm large bandwidth is reported. The high contrast grating (HCG) structure has been designed in order to enhance the properties of mid-infrared VCSEL devices by replacing the top Bragg mirror of the cavity. A robust optimization algorithm has been implemented to design the HCG structure not only as an efficient mirror but also as a robust structure against the imperfections of fabrication. The design method presented here can be easily adapted for other HCG applications at different wavelengths.

Mid-infrared sub-wavelength grating mirror design: tolerance and influence of technological constraints

A Si/Si3N4 high contrast grating mirror has been designed for a VCSEL integration in mid-infrared (λ = 2.65xa0μm). The use of an optimization algorithm which maximizes a VCSEL mirror quality factor allowed the adjustment of the grating parameters while keeping large and shallow grating pattern. The robustness with respect to fabrication error has been enhanced thanks to a precise study of the grating dimension tolerances. The final mirror exhibits large high reflectivity bandwidth with a polarization selectivity and several percent of tolerance on the grating dimensions.

Robust Design by Antioptimization for Parameter Tolerant GaAs/AlOx High Contrast Grating Mirror for VCSEL Application

Slightly flared lasers are investigated in order to minimize the longitudinal spatial hole burning impact on the output power saturation of 1480-nm pump lasers. In such a device, the stripe width is narrow at the rear facet for strong single lateral mode operation whereas at the front facet the stripe widens in order to reduce the photon density and as a consequence decrease gain saturation through hole burning effect. We proposed a slightly flared lasers design in order to maintain a uniform photon density along the active stripe. Experimentally, this novel structure exhibits single transverse-mode operation and a 30% output power improvement is obtained compared to the straight active waveguide.