New integrated buried laser-ridge modulator with identical active layer

Integrated laser modulators are attractive devices for wavelength-division-multiplexing optical systems due to their compactness, high output power, and low cost. Their fabrication simplicity is a way to decrease further the transmitter cost and address new opening markets of short range and metropolitan networks. We report a new integration scheme electroabsorption-modulator distributed feedback (DFB) laser based on well-established industrial solutions for discrete buried ridge (BRS) DFB lasers and discrete shallow ridge modulators. Processing simplification with an identical active layer has been possible due to a good behavior of strongly positively detuned BRS lasers. The integrated devices demonstrated 30-dB extinction ratio with 10-GHz bandwidth and P/sub out/=10 dBm for emission in 1.55-/spl mu/m range.     

Si/CoSi2/Si permeable base transistor obtained by silicon molecular beam epitaxy over a CoSi2 grating

Permeable base transistors have been fabricated by silicon molecular beam epitaxy over a CoSi2 grating, epitaxially grown on top of an Si wafer. The Si channel widths range from 4 ?m down to 1 ?m. Collector current/voltage characteristics are presented which exhibit the main expected features of an Si permeable base transistor.     

Demonstration of (λ≈11.5-μm) GaAs-based quantumcascade laser operating on a Peltier cooled element

We demonstrate an average power of 2 mW at λ≈11.5 μm and 233 K, for a GaAs-based quantum cascade laser mounted on a Peltier cooler. Furthermore, a maximum operating temperature of 285 K has also been demonstrated. These results are attributed to the excellent intrinsic thermal characteristics of these lasers and good heat management, achieved through the structural design and epi-side down mounting. Measurements show a thermal resistance of 6.7 K/W at 233 K, in good-agreement with our models     

Wavelength conversion by optimized monolithic integrated Mach-Zehnder interferometer

Semiconductor optical amplifiers have been monolithic integrated in a passive symmetric Mach-Zehnder interferometer to form a compact polarization insensitive all-optical wavelength converter operating at up to 10 Gb/s. A simple method for reducing the impact of input power variations is proposed that increases the input power dynamic range from 4-8 dB.     

Active lossless monolithic one-by-four splitters/combiners usingoptical gates on InP

Active one-by-four splitters/combiners were fabricated on InP from the monolithic integration of waveguides and amplifiers. The device exhibited propagation loss below 1.5 dB·cm^-1, S-bend loss of 0.2 dB per bend, a 3-dB optical bandwidth of 23 nm, a mean optical crosstalk and extinction ratio of, respectively, 37 dB and 42 dB. On all paths, at least 0 dB insertion loss (fiber to-fiber gain up to 2.8 dB) as well as a low polarization sensitivity (below 1.0 dB) were demonstrated. This device can be used as the basic building block of bit-rate transparent switches for optical routing and broadcasting     

Polarisation insensitive 1.55 mu m semiconductor integrated optical amplifier with access waveguides grown by LP-MOCVD

A 1.55 mu m GaInAsP/InP optical amplifier integrated with access waveguides provides 0 dB fibre to fibre gain at only 47 mA bias current and a 5 dB saturation gain already high enough to design 0 dB integrated complex circuits. Polarisation gain dependence and gain ripple are less than 0.5 dB and 0.7 dB, respectively.<>     

An all-optical wavelength-converter with semiconductor opticalamplifiers monolithically integrated in an asymmetric passiveMach-Zehnder interferometer

An all-optical wavelength-converter based on monolithic integration of a Mach-Zehnder interferometer and integrated semiconductor optical amplifiers was demonstrated. This device exhibited high stability, penalty-free conversion at 5 Gbit/s (at a BER of 10⁹), no-excess penalty after a transmission over 60 km on standard fiber, and low signal-polarization dependency. The device operated in a 26-nm-wide optical window     

Monolithic integration of GaAs MESFET and InP/InGaAsP 2*2 optical switch

An optical switching OEIC (optoelectronic integrated circuit), consisting of a GaAs MESFET and an InP/InGaAsP 2*2 buried waveguide optical switch, is reported for the first time. Fully monolithic integration is obtained by heteroepitaxial GaAs-on-InP growth and photolithographical interconnection. The combined OEIC allows switching voltages of about 1 V with an extinction ratio of -6 dB.<>     

Experimental comparison of autodyne and heterodyne laser interferometry using an Nd:YVO₄ microchip laser

Using an Nd:YVO? microchip laser with a relaxation frequency in the megahertz range, we have experimentally compared a heterodyne interferometer based on a Michelson configuration with an autodyne interferometer based on the laser optical feedback imaging (LOFI) method regarding their signal-to-noise ratios. In the heterodyne configuration, the beating between the reference beam and the signal beam is realized outside the laser cavity, while in the autodyne configuration, the wave beating takes place inside the laser cavity, and the relaxation oscillations of the laser intensity then play an important part. For a given laser output power, object under investigation, and detection noise level, we have determined the amplification gain of the LOFI interferometer compared to the heterodyne interferometer. LOFI interferometry is demonstrated to show higher performance than heterodyne interferometry for a wide range of laser powers and detection levels of noise. The experimental results are in good agreement with the theoretical predictions.     

Sensitivity of synthetic aperture laser optical feedback imaging

In this paper, we compare the sensitivity of two imaging configurations, both based on laser optical feedback imaging (LOFI). The first one is direct imaging, which uses conventional optical focalization on target, and the second one is made by a synthetic aperture (SA) laser, which uses numerical focalization. We show that SA configuration allows us to obtain good resolutions with high working distance and that the drawback of SA imagery is that it has a worse photometric balance in comparison to a conventional microscope. This drawback is partially compensated by the important sensitivity of LOFI. Another interest of SA relies on the capacity of getting three-dimensional information in a single x-y scan.