InP integrated pulse shaper with 48 channel, 50 GHz spacing amplitude and phase control

Abstract

Ultrafast optical pulse shaping supports a broad number of applications, ranging from ultrafast time-resolved spectroscopy to RF photonics [1]. Conventional pulse shapers rely on bulk optics and use liquid crystal spatial light modulators, with reconfiguration times limited to milliseconds. Integrated optical pulse shapers offer not only size advantage but also the potential for much faster reconfiguration by using electro-optic pulse shaping elements. Integrated pulse shapers usually employ an arrayed waveguide grating (AWG) to separate the input light into its constituent wavelengths, process each wavelength band using an array of on-chip components, and then recombine the light again relying on AWG action. AWG-based integrated pulse shapers with independent thermo-optic amplitude and phase control have been demonstrated in silica, but the reconfiguration time remains limited [2]. Our group previously reported a 32-channel InP arrayed waveguide grating pulse shaper (AWGPS) with 25 GHz channel spacing and an array of semiconductor optical amplifiers (SOAs) for spectral amplitude control. This work demonstrated amplitude shaping fidelity good enough to apply to RF photonic bandpass filtering with sidelobe suppression >35 dB as well as microsecond-scale reconfiguration [3]. Other groups have also demonstrated pulse shaping with integrated InP with either amplitude or phase control but not both [4]. In this work we report preliminary characterization of a 48 channel InP shaper at 50 GHz channel spacing, provisioned with both channel-by-channel phase adjusters and SOA gain elements (Fig. 1). To our knowledge this constitutes the first demonstration of an operable integrated InP pulse shaper with independent intensity and phase control.