This paper proposes a scheme to increase possible patterns of wavelength-conversion for an optical packet switch (OPS) with parametric wavelength converters (PWCs) by obtaining additional converted wavelengths using the existing resources. It is called a recursive parametric wavelength conversion (RPWC) scheme. A PWC uses a pump wavelength to define the original and converted wavelengths, called wavelength conversion pairs. None of conversion pairs from any PWCs can sometime support the request, although some wavelengths at the requested output fiber are available. Therefore, packet loss occurs and several conversion pairs are wasteful. In RPWC, unused conversion pairs are used to create additional conversion pairs. The OPS allows each wavelength to be converted using combination of unused conversion pairs using more than one PWC, instead of using only a single PWC as in a conventional scheme. Simulation results show that RPWC achieves lower packet loss rate than the conventional scheme, under both uniform and non-uniform traffic. To show the feasibility of RPWC, we develop a prototype of an optical switch with RPWC and demonstrate it in experiment.