Mickael Faugeron

High Power Three-Section Integrated Master Oscillator Power Amplifier at 1.5 μm

We present the design and the performance of a monolithically integrated master oscillator power amplifier at 1.5 μm. The three-section device includes a distributed feedback laser, a modulation section, and a high power tapered amplifier. In order to mitigate the coupling effects of the light reflected at the facets, the device has been designed with a bent longitudinal axis and a tilted front facet. The device delivers >400 mW mode-hopping free output power. In static regime, the modulation section allows an extinction ratio of 35 dB.

Ultralow Noise and High-Power VECSEL for High Dynamic Range and Broadband RF/Optical Links

We describe a compact, ultralow noise, and high-power semiconductor laser implemented in a high performances wideband externally modulated optical link. The laser is based on a vertical external cavity surface emitting laser (VECSEL) designed for high-power and low-noise operation. Thanks to a specific design of the gain chip, the half-VCSEL, based on a metamorphic Bragg mirror and a report on a copper substrate, an optical power of 110 mW is obtained at 1.55 μm in the single frequency regime. For low-noise operation, the laser cavity is designed for free-relaxation-oscillations operation, i.e., in the so-called class-A regime. The Class-A VECSEL exhibits a relative intensity noise below -170 dB/Hz over a wide frequency bandwidth, from 300 MHz to 40 GHz, except at the laser free spectral range (20.4 GHz). In the low-frequency range, the laser noise, mainly due to transfer of pump noise to laser noise, goes from -110 dB/Hz at 1 kHz down to -158 dB/Hz at 10 MHz. Two externally modulated optical links are implemented and compared in terms of the RF gain and the noise figure. The first optical link is based on the ultralow noise class-A VECSEL and the second one is based on a low noise class-B DFB laser. Thanks to the outstanding noise properties of the designed VECSEL, the VECSEL-based optical link outperforms the DFB-based one, in particular for frequencies larger than 20 GHz.

Atmospheric CO2 remote sensing system based on high brightness semiconductor lasers and single photon counting detection

We propose an integrated path differential absorption lidar system based on all-semiconductor laser sources and single photon counting detection for column-averaged measurements of atmospheric CO2. The Random Modulated Continuous Wave (RM-CW) approach has been selected as the best suited to semiconductor lasers. In a RM-CW lidar, a pseudo random sequence is sent to the atmosphere and the received signal reflected from the target is correlated with the original sequence in order to retrieve the path length. The transmitter design is based on two monolithic Master Oscillator Power Amplifiers (MOPAs), providing the on-line and off-line wavelengths close to the selected absorption line around 1.57 µm. Each MOPA consists of a frequency stabilized distributed feedback master oscillator, a bent modulator section, and a tapered amplifier. This design allows the emitters to deliver high power and high quality laser beams with good spectral properties. An output power above 400 mW with a SMSR higher than 45 dB and modulation capability have been demonstrated. On the side of the receiver, our theoretical and experimental results indicate that the major noise contribution comes from the ambient light and detector noise. For this reason narrow band optical filters are required in the envisioned space-borne applications. In this contribution, we present the latest progresses regarding the design, modeling and characterization of the transmitter, the receiver, the frequency stabilization unit and the complete system.

Asymmetrical cladding quantum dash mode-locked laser for Terahertz wide frequency comb

We have developed a quantum dash (QDs) mode locked laser (MLL) using an asymmetrical cladding for high frequencies microwave generation. The laser exhibits more than 400 mW output power. The optical comb is 9.2 nm wide with 10 GHz free spectral range. Thanks to optical compression we have increased the signal to noise ratio by 25 dB. The MLL can be locked on an external source. We have demonstrated RF lines from 10 to 120 GHz with 10 GHz spacing.

Modulation Performance of Three-Section Integrated MOPAs for Pseudorandom Lidar

The suitability of a three-section master oscillator power amplifier for pseudorandom lidar is investigated by means of the experimental characterization and analysis of its emission characteristics under modulation. The proposed architecture consists of a distributed feedback laser, a modulation section, and a tapered semiconductor optical amplifier. The modulation section acts as an absorber or amplifier when driven at zero or positive bias. Under pseudorandom modulation at 25 Mb/s, a high optical modulation amplitude and extinction ratio were achieved. The characterization of the emission spectra under modulation revealed typical features of frequency modulation due to the carrier-induced refractive index changes.

Monolithic InP master oscillator power amplifier for free space optical transmissions at 1.5 µm

Interest in free space optical communications has increased in the last decades as it has many advantages over RF communications, especially for space-borne applications. However, high power, good spectral quality and beam quality are needed for efficient data transmission over long distances. To meet the need of having lightweight and compact laser sources with such qualities for FSO, semiconductor based MOPA systems (Master Oscillator Power Amplifier) have been developed. In this paper we present the experimental results and compare them to simulation results for a threesection monolithically integrated semiconductor Master Oscillator Power Amplifier emitting at 1.5 μm wavelengths, designed for LIDAR applications that can also be used for free space telecommunications. The MOPA includes a distributed feedback laser section for single mode light emission, an intermediate section for data modulation and a flared semiconductor optical amplifier section for power amplification, which allows us to generate a high power beam with good spectral characteristics. The impact of bias conditions of the different device sections and device design on performances have been studied. Single mode operation at 4 different wavelengths near 1550 nm is achieved for optical output power up to 400 mW in continuous-wave (CW) regime for a SOA current of 3 A and 800 mW for SOA pulsed operation for currents up to 5 A. Near-field profile is also analyzed for different modulator current. Small-signal dynamic response is measured and analyzed.

Laser module based on monolithically integrated Mopas at 1.5 μm for space-borne lidar applications

Space-borne lidar systems require laser transmitters with very good performance in terms of output power, beam quality, conversion efficiency, long term reliability and environmental compatibility. Atmospheric gas sensing additionally requires spectral purity and stability.

Three-section master oscillator power amplifier at 1.57 μm for lidar measurements of atmospheric carbon dioxide

We present experimental results on a three-section master oscillator power amplifier at 1.57 μm to be applied in an integrated path differential absorption LIDAR system for column-averaged atmospheric CO2 measurements. The application requires high power and good beam quality together with spectral purity and modulation capacity to be used in a random modulation CW LIDAR system. The device consists of a distributed feedback laser acting as master oscillator, a bent modulator section and a tapered optical amplifier section with a tilted front facet to avoid coupled cavity effects. The modulator section acts as an absorber or amplifier when driven at zero or positive bias. Devices with different geometries and epitaxial structures were fabricated and characterized, presenting CW output powers higher than 350 mW and stable single mode emission. At the frequency required by the application (12.5 MHz) a high optical modulation amplitude and extinction ratio were achieved.

Towards a low noise class-A hybrid III-V/silicon laser

We report on a hybrid III-V/Silicon laser, designed for low noise class-A dynamics. The laser exhibits a Relative Intensity Noise below -145 dB/Hz from 100 MHz to 40 GHz.

High power mode locked quantum dash 1.5 μm laser with asymmetrical cladding

We present a quantum dash laser with more than 120 mW/facet at 1.2 A based on an asymmetrical cladding. Passive mode-locking with an RF -3dB linewidth of 3.2 kHz at 20.7 GHz has been demonstrated.