The Fiber Imager foR a Single Telescope (FIRST) is a visible spectro-interferometer (600-760 nm, R~400) installed on the Subaru telescope's extreme adaptive optics platform (SCExAO). It provides high-precision spatial coherence measurements with high angular resolution (~8 mas at 656 nm, ~1% coherence accuracy) by combining light from sub-apertures of the telescope pupil. We present two upgrades of the instrument towards H𝛼 detection of protoplanets. We report on the integration of a new 4000-resolution spectrograph and on the sensitivity of the instrument. We also present the characterisation of a high performance visible photonic integrated circuit prototype used for the interferometric combination of 5 sub-apertures.
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.
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