Takuya KATO, Tsuyoshi KONISHI, Takashi NISHITANI, and Kazuyoshi ITOH

Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan

(Received July 15, 2008; Accepted November 21, 2008)

We propose and demonstrate an all-optical analog-to-digital conversion system with a spatial coding method using a designed filter. To make available codes more flexible, the design technique for a computer-generated hologram is introduced to our spatial coding scheme. By designing the spatial coding filter appropriately, this coding scheme enables us to output various digital signals as spatial patterns. By combining this coding method with the optical quantization method using soliton self-frequency shifting in a fiber, the proposed system converts analog sampled signals into arbitrary digital signals. Preliminary experimental results show that 3-bit Gray codes are successfully output as spatial patterns using the designed spatial coding filter.

Key words: optical signal processing, optical analog-to-digital conversion, optical coding, computer-generated hologram (CGH), nonlinear fiber optics, free space optics, soliton self-frequency shift (SSFS)