On-Chip All-Optical Haar Transform Based on A 4x4 MMI Coupler Cascaded with a 2x2 MMI Coupler for Image Compression

Abstract

We present a new method for image compression in all-optical domain. The new hardware architecture is suitable for directly integrating with digital cameras for image processing. The proposed architecture is based on the optical Haar wavelet transform (HWT) using only one 4x4 multimode interference (MMI) coupler cascaded with a 2x2 MMI coupler. The proposed structure can provide a large fabrication tolerance of ±2 µm in length, which is suitable for the current existing CMOS (Complementary Metal Oxide Semiconductor) technology. The numerical simulations show that the compression algorithms have been implemented successfully in all-optical domain. The compression ratios from 10-50% are presented with the Peak Signal to Noise Ratios of 40-131 dB. The processing of images therefore is at very high speed.

Keywords: Image Compression, Haar Wavelet Transform, Signal Transform, Optical Signal Processing, Optical Image Processing.