Detuning modulated composite segments for robust optical frequency conversion

Abstract The creation of efficient broadband frequency conversion devices while maintaining robustness to manufacturing and setup errors is crucial for accurate multiphoton spectroscopy, broadband imaging and the design of robust optical sources. Traditionally, nonlinear optical conversion processes are either efficient but narrowband or broadband but with low photon conversion yield. Several methods have been introduced in recent years to obtain both with great success, among them we can find adiabatic frequency conversion and Shaka–Pines composite segmented design. Here, we expand the composite design and introduce the detuning modulated composite segmented (DMCS) scheme in nonlinear optics, which offers a broadband, efficient and robust method for frequency conversion. We also present the constant-length DMCS scheme, which offers multiple efficient and robust wavelength regimes for broadband upconversion. We apply these schemes to a system of quasi-phase-matching crystal for the sum frequency generation process, and demonstrate the high robustness and bandwidth of the composite schemes. We show that these schemes are robust to temperature and crystal length variations and can have a superior conversion bandwidth under length and power constraints compared to other conversion schemes, such as periodically poled and adiabatic chirped crystals. We believe that the new family of DMCS schemes will have many uses in applications of frequency conversion, due to their robustness, low energy demand and compact size.