• LIDAR is based on well known principles of RADAR
  • Radar is well known technology existing since the beginning of the 20th century
  • LIDAR uses optical frequencies instead of radio waves


Lidar and Radar


LIDAR using phased arrays improves directionality using interference

  • Output profile of a LIDAR is the product of the array factor and the single antenna far field.


phased array schematic

Phased array results

Phased Array equation

N: number of antennas

k: wave vector

w_i: complex weight for element I

r_i: position vector for antenna element i

Phased Array equation 2

LIDAR using on-chip waveguide antennas

  • Corrugated waveguides are used as antennas
    corrugated waveguid
  • Pitch corrugation is chosen so that Bragg reflected light is scattered to free space
    Bragg reflection equations
  • Multiple such antennas are used in an array to for beam forming
    Array of waveguides

Lidar modeling in Lumerical

  • MODE analysis of waveguide to calculate n_eff
  • Choosing optimum antenna separation so that there is minimum coupling between adjacent antennas
  • 3d FDTD simulation to calculate bandgap region
  • Far field analysis to calculate far-field profile of a single antenna
  • Array factor multiplication to see beam steering


Calculate effective refractive index for thinner and thicker cross-sections

Lidar Mode picture

Model results

  • Optimizing separation to minimize cross-coupling
  • We perform simulations with 2 waveguides and calculate after how much length can 10% of light from waveguide 1 couple to waveguide 2

Mode optimization

Mode optimization results


  • Calculate the band-gap region
  • Observe wavelength dependent single antenna scattering

FDTD graph

fdtd phased array results

  • 2d beam-steering(θ,ϕ) using results from FDTD

11 beam steering

System level simulations using INTERCONNECT

  • Integrate multiple components
  • Simulate an actual experiment
  • Extensive library of standard components
  • Custom components can be created
  • Allows integration of optical, electrical and thermal elements
12 interconnect

  • We see the effect of applying a optical delay using a voltage ramp on an optical modulator
  • For a given range of voltage values we can monitor θ,ϕ of the steered beam and beam properties.

13 phased array steering

Beam Steering


Detector design

  • Detector design using Lumerical
  • Optical simulations to study light absorption in detectors

Example: We look at Germanium detectors on Si

15 GE on SI detector

Ge on Si detector cross-section

15 fdtd detector

Intensity profile in Ge using FDTD

  • Electrical simulations using CHARGE can be used to calculate the photocurrent and the dark current for the detector
    16 10um current vias
  • Electrical simulations using CHARGE can be used to calculate the responsivity and gain
17 responsivity
  • Circuit simulations using INTERCONNECT can be used to simulate detector response to weak modulated signal
18 Gain


Post by Sachin
May 16, 2022

Get started with simulation TODAY!

Not sure where to start? Reach out and see how we can help.