The present invention provides a method which can significantly increase the signal-to-noise ratio of an ultrasound-modulated optical signal by overcoming the shallow depth problem of in vivo optical imaging in existing optical imaging by use of a quantum optical phenomenon based on ultraslow light and nondegenerate phase conjugation and which can be applied directly not only to medical optical imaging, but also to medical photodynamic therapy, through slow light amplification of phase conjugate waves.

The present invention relates to an on-chip ultra-wideband white noise generation apparatus based on chaotic micro-ring optical frequency combs. The apparatus includes semiconductor lasers, micro-ring resonators, and a photoelectric detector. The semiconductor lasers, the micro-ring resonators, and the photoelectric detector are integrated on a same chip substrate; and after outputting continuous light which is injected into the micro-ring resonators, the semiconductor lasers have a combined effect of four-wave mixing, self-phase modulation, cross-phase modulation, and chromatic dispersion, and after the continuous light is outputted by through ports of the micro-ring resonator, chaotic optical frequency combs at an equal interval are generated, so that a high bandwidth noise signal is achieved by frequency beating of multiple chaotic optical frequency combs. Compared with existing noise generation apparatuses, the present invention features a simple structure and has the advantages of a smaller volume, low power consumption, high stability, and an expandable bandwidth.

An optical parametric oscillator (OPO) system comprises an optical waveguide including a hollow core containing a fluid, wherein the optical waveguide is configured to receive pump light and to convert the pump light into signal light and idler light via a third order non-linear optical effect. The OPO system further comprises an optical feedback arrangement for recycling at least a portion of the signal light and/or for recycling at least a portion of the idler light in an optical cavity that includes the optical waveguide. The OPO system may be used, in particular though not exclusively, in metrology, gas and solid-state spectroscopy, laser-assisted manufacturing, semiconductor technology, biomedicine, healthcare, and scientific laboratory use.