Control of the carrier-envelope phases of a synchronously pumped femtosecond optical parametric oscillator and its applications

The intrinsic synchronization, multi-color outputs and related carrier-envelope phases (CEP) among pulses bring advantages to synchronously pumped femtosecond optical parametric oscillators and the pumping sources for broadband frequency comb generation and ultrashort waveform coherent synthesis. In this paper, we discuss our latest research results in this field, which cover the following aspects: the phase relationship and energy conservation law in an OPO and related experimental verification; control of the pumping Ti:sapphire femtosecond laser’s CEP by self-referencing technology, and its repetition-rate locking by piezoelectric transducer (PZT); CEP locking of the pulses from the OPO by beating the non-phase-matched visible outputs against pump supercontinuum to obtain a driving signal for a fast PZT on the OPO end mirror; the generation of a broadband frequency comb spanning from 400 nm to 2.4 μm with 1.2 kHz bandwidth; and the realization of coherent interference between phase controlled pump pulses and signal second harmonic pulses. Supported by UK Engineering and Physical Sciences Research Council (EPSRC), Coherent Inc. and the National Natural Science Foundation of China (Grant No. 60308001)