Philippe Brosson

Analytical model of a semiconductor optical amplifier

The spatial dependence of the material gain is introduced in the model of a semiconductor optical amplifier. Analytical expressions of the profiles of the carrier density, spontaneous emission, and amplified fields are obtained for amplifiers with arbitrary facet reflectivities. The nonuniformity of the carrier density is demonstrated in the case of low facet reflectivities. The model predicts the output saturation power and gain ripple, with good agreement with experimental results in resonant and traveling-wave amplifiers. Very low-gain ripple measured in low facet reflectivities amplifiers is explained by the model. A comparison with the uniform gain model shows that important deviations can occur in the case of low facet reflectivities. It is also shown that with the currently achievable low facet reflectivities, the maximum available gain is limited by spontaneous emission. >

High-performance semiconductor optical amplifier array for self-aligned packaging using Si V-groove flip-chip technique

A high performance four-tilted stripe InGaAsP semiconductor optical amplifier array, with low polarization sensitivity and very low-gain ripple, compatible with self-aligned flip-chip mounting on a Si motherboard is reported. Up to 32 dB of internal gain with 2-dB polarization sensitivity is obtained. A multifiber module has been realized, following an almost static optical alignment procedure, showing no degradation of the SOA array performances. Fiber-to-fiber gain, measured on the four stripes, is 14.4/spl plusmn/1.3 dB with a gain ripple below /spl plusmn/0.1 dB.<<ETX>>

Design rules for a low-chirp integrated DFB laser with an electroabsorption modulator

Feedback from the front facet of an integrated DFB laser with an electroabsorption modulator generates additional chirp to the single modulator. The reduction of the sensitivity to that feedback is in tradeoff relation with the external differential quantum efficiency and the single-mode yield. We introduce a figure-of-merit for the feedback sensitivity. It is obtained from the modeling of the small signal frequency modulation (FM). It indicates design rules for low-chirp and high-efficiency devices.

Modeling of the static and dynamic responses of an integrated laser Mac-Zehnder modulator and comparison with an integrated laser EA modulator

In an integrated laser Mach-Zehnder modulator (ILMZ), as well as in an integrated laser electroabsorption (EA) modulator (ILM), optical feedback can lead to a high level of frequency chirp and relaxation oscillations, compared to the case of a laser coupled into a discrete external modulator through an optical isolator. To investigate these aspects, in the particular case of the ILMZ, an original model has been developed. Analytical expressions of the frequency modulation (FM) and amplitude modulation (AM) responses of two types (2/spl times/1 and 2/spl times/2 output couplers) of ILMZ are given by the model, and the direct and indirect contributions to the FM responses are identified. The model can be used in the design and optimization of the ILMS, aiming at a small optical frequency chirp and small AM perturbation at resonance frequency. Numerical simulation of the small signal response (AM and FM modulations) has been performed for both ILMZ configurations and an ILM. A lower chirp is obtained for the ILMZ compared to the ILM. A high extinction ratio and a low negative effective chirp parameter are predicted at output B of the 2/spl times/2 ILMZ, as well as for the /spl pi/-phase-shifted 2/spl times/1 ILMZ.

Analytical expressions for the FM and AM responses of an integrated laser-modulator

The need for low-chirp and compact transmitters for high-bit-rate optical links has led to the development of integrated laser electroabsorption modulators (ILM). We have investigated feedback effects inducing frequency chirp by developing a model treating the ILM as a whole and obtained analytical expressions of the FM and AM responses. The variation of the frequency chirp with the residual facet reflectivity of the modulator section is calculated. The model predicts the unusual peak in the measured frequency responses and has been used to define design rules.

III-V Heterostructures For Laser Emission In The 2.55 µm Wavelength Region

III-V double heterostructure laser diodes emitting at room temperature near 2.55 μm can be prepared using InAsSbP, GaInAsSb or InAlAsSb active zones and GaAlAsSb confinement layers. The limits of the solid phase miscibility gap of these quaternary solid solutions were determined at 530°C. A phenomenological model giving the threshold current density of double heterostructure injection lasers is presented, and applied to the 2.55 μm emitting InAsSbP/ GaAlAsSb and GaInAsSb/GaAlAsSb DH lasers. It is shown that threshold currents are mainly controlled by Auger recombination currents. Thq low value of the overall Auger recombination coefficient for GaInAsSb alloy (C = 1.0 x 10 -28 cm6/s at 2.2 μm) gives threshold current densities varying from 4.5 kA/cm2 to 3 kA/cm2 at room temperature for Ga 0.73 In 0.27 As 0.24 Sb 0.76/Ga 1-x Al x As y Sb 1-y /GaSb 2.55 μm DH lasers when x is varied from 0.4 to 0.7.

Dynamics and performance of hybrid distributed Bragg reflector lasers including a chirped fiber grating

In this work, we report the spectral and modulation characteristics, as well as bit-error-rate performances of stabilized hybrid distributed Bragg reflector lasers including a chirped fiber grating. An original analysis of such lasers based on a modified second order rate equation will also be presented to explain the observed stability behavior.