  Automatic reconfiguration of optical filters is the key to novel flexible RF
photonic receivers and Software Defined Radios (SDRs). Although silicon
photonics (SiP) is a promising technology platform to realize such receivers,
process variations and lack of in-situ tuning capability limits the adoption of
SiP filters in widely-tunable RF photonic receivers. To address this issue,
this work presents a first `in-situ' automatic reconfiguration algorithm and
demonstrates a software configurable integrated optical filter that can be
reconfigured on-the-fly based on user specifications. The presented
reconfiguration scheme avoids the use of expensive and bulky equipment such as
Optical Vector Network Analyzer (OVNA), does not use simulation data for
reconfiguration, reduces the total number of thermo-optic tuning elements
required and eliminates several time consuming configuration steps as in the
prior art. This makes this filter ideal in a real world scenario where user
specifies the filter center frequency, bandwidth, required rejection & filter
type (Butterworth, Chebyshev, etc.) and the filter is automatically configured
regardless of process, voltage & temperature (PVT) variations. We fabricated
our design in AIM Photonics' Active SiP process and have demonstrated our
reconfiguration algorithm for a second-order filter with 3dB bandwidth of 3
GHz, 2.2 dB insertion loss and >30 dB out-of-band rejection using only two
reference laser wavelength settings. Since the filter photonic integrated
circuit (PIC) is fabricated using a CMOS-compatible SiP foundry, the design is
manufacturable with repeatable and scalable performance suited for its
integration with electronics to realize complex chip-scale RF photonic systems.
