We discuss here the feasibility of an optical parametric oscillator integrated on a GaAs chip, after reviewing the recent frequency conversion experiments using from birefringence in GaAs/oxidized-AlAs (Alox) waveguides. Recently, phase-matching has been demonstrated for the first time in a GaAs-based waveguide, using form birefringence in multilayer heterostructures GaAs/Alox. Birefringence n(TE)- n(TM) from 0.15 to 0.2 have been measured for different GaAs/Alox waveguides, which is sufficient to phase match mid-IR generation between 3 micrometers and 10 micrometers by difference frequency generation form two near-IR beams. A second step was the observation of parametric fluorescence. Results on parametric fluorescence at 2.1 micrometers will be described, in an oxidized AlGaAs form-birefringent waveguide, consisting of a high-index, strongly birefringent GaAs-Alox core embedded in an AlGaAs cladding. One of the most existing perspectives opened with this new type of nonlinear material is the realization of an optical parametric oscillator on a GaAs chip. To this aim, minimization of losses is the most crucial point. A typical calculated value of this threshold is less than 70 mW for 1 cm-1 losses, and with 90 percent reflection coefficients. The level of losses has been reduced from 2 cm-1 in ridges obtained by a standard reactive ion etching technique, to less than 0.5 cm-1 in ridges realized with a more refined reactive ion etching process, using a 'three layer' mask. There is still a need for an improvement of the waveguide fabrication process, before reaching the oscillation threshold.