Image of Nemanja Jovanovic

Nemanja Jovanovic (California Institute of Technology)

Campus PI


  • Dimitri Mawet (California Institute of Technology)
  • Pradip Gatkine (California Institute of Technology)
  • Stephanie Leifer (Jet Propulsion Laboratory)
  • Charles Beichman (Jet Propulsion Laboratory)
  • Gautam Vasisht (Jet Propulsion Laboratory)
  • Jeffrey Jewell (Jet Propulsion Laboratory)


Project Goal:

Build an all-photonic Dynamic Spectral Flattener (DSF) to flatten the spectrum of a laser frequency comb to test with The Palomar Radial Velocity Instrument (PARVI) from 1400-1800 nm.

Year 1 Goals:

DSF test facility:

  1. Design a photonic characterization facility
  2. Procure, build, automate and commission the photonic characterization facility

DSF device development:

  1. Produce 400 nm bandwidth, 20 channel DSF design
  2. Procure 400 nm bandwidth DSF device
  3. Characterize the 400 nm bandwidth DSF device in the lab

Milestone: Laboratory demonstration and characterization of a 400-nm bandwidth DSF.

Year 2 Goals:

  1. Get thermo-optic phase shifters working in full enchilada
  2. Demonstrate how flat a spectrum can be made with both thermo-optic phase shifters and MZIs
  3. Characterize the device all the way up to 1800 nm
  4. Test stability
  5. Test with a laser frequency comb at Caltech
  6. Deploy to Palomar and test with PARVI
  7. Order a second round of devices with refined specifications and characterize

Image of broadband all-photonic spectrum shaper device
Image of broadband all-photonic spectrum shaper setup

Experimental setup for characterizing the broadband all-photonic spectrum shaper. The light source for the tests was either a super-luminescent diode or an LFC. A paddle wheel polarization controller was used to align the polarization of the source with the TE mode of the waveguides. Light was injected via a v-groove array. The fully packaged PIC is shown. The electrodes on the circuit (chromium plated) as well as the AWGs can easily be seen in the photo. The output was routed to an OSA.


Nemanja Jovanovic, Pradip Gatkine, Boqiang Shen, Maodong Gao, Nick Cvetojevic, Katarzyna ŁawniczukRonald Broeke, Charles Beichman, Stephanie Leifer, Jeffrey Jewell, Gautam Vasisht, and Dimitri Mawet "An all-photonic, dynamic device for flattening the spectrum of a laser frequency comb for precise calibration of radial velocity measurements", Proc. SPIE 12188, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V, 121885D (29 August 2022);