Picosecond optical pulse sources have been playing an important role in ultrafast processes such as optical communications and biomedical imaging applications. Today there is a growing demand of short pulse generation in non-conventional wavelength bands, for example, in ultra-fast optical communications. However, high-quality picosecond laser is generally not available at some non-conventional wavelengths due to the lack of efficient gain medium. Thanks to the ultra-fast response, wide-gain bandwidth, high gain and large detune from the pump of fiber optical parametric amplifier (FOPA), efficient short pulse generation is possible at non-conventional wavelengths.
A fiber OPA relies on the third-order nonlinear susceptibility x(3) of glass: a signal frequency at ws will be amplified by a strong co-propagating pump at wp in a fiber through this parametric process. Therefore, OPA may find applications as optical amplifiers in WDM transmission. Another frequency, called idler, will also be generated at wi = 2wp – ws. This contains essentially the same modulation information as the input signal, but with an inverted spectrum.
Conventionally, optical parametric oscillator (OPO) based on x(2) nonlinear effect of crystals is utilized for parametric oscillation. This technique has a wide range of applications in optical research and development. However, this approach requires a dedicated alignment for optimal operation. Fiber optical parametric oscillators (FOPO), which based on parametric gain provided by fiber OPA, eliminate the need for alignment and allow further integration with fiber components.
In this presentation, we demonstrate a fully fiber-integrated widely-tunable picosecond optical parametric oscillator based on highly-nonlinear fiber, with the tuning range as wide as 250 nm around 1550 nm. The totally fiber-integrated nature of this source allows completely self-alignment and further integration to other systems. This scheme may be useful in generating short pulse for potential ultra-fast communication in non-conventional wavelength bands and biomedical imaging applications.