Ring filter

Ring filter#

Calculations#

For a ring resonator we need to define:

Optical parameters:

coupling coefficient: will define resonance extinction ratio for a particular ring loss.
Free spectral range.

Electrical parameters:

VpiL
Resistance

import gdsfactory as gf
import numpy as np


def ring(
    wl: np.ndarray,
    wl0: float,
    neff: float,
    ng: float,
    ring_length: float,
    coupling: float,
    loss: float,
) -> np.ndarray:
    """Returns Frequency Domain Response of an all pass filter.

    Args:
        wl: wavelength in  um.
        wl0: center wavelength at which neff and ng are defined.
        neff: effective index.
        ng: group index.
        ring_length: in um.
        coupling: coupling coefficient.
        loss: dB/um.
    """
    transmission = 1 - coupling
    neff_wl = (
        neff + (wl0 - wl) * (ng - neff) / wl0
    )  # we expect a linear behavior with respect to wavelength
    out = np.sqrt(transmission) - 10 ** (-loss * ring_length / 20.0) * np.exp(
        2j * np.pi * neff_wl * ring_length / wl
    )
    out /= 1 - np.sqrt(transmission) * 10 ** (-loss * ring_length / 20.0) * np.exp(
        2j * np.pi * neff_wl * ring_length / wl
    )
    return abs(out) ** 2


if __name__ == "__main__":
    import matplotlib.pyplot as plt

    loss = 0.03  # [dB/μm] (alpha) waveguide loss
    neff = 2.46  # Effective index of the waveguides
    wl0 = 1.55  # [μm] the wavelength at which neff and ng are defined
    radius = 5
    ring_length = 2 * np.pi * radius  # [μm] Length of the ring
    coupling = 0.5  # [] coupling of the coupler
    wl = np.linspace(1.5, 1.6, 1000)  # [μm] Wavelengths to sweep over
    wl = np.linspace(1.55, 1.60, 1000)  # [μm] Wavelengths to sweep over
    ngs = [4.182551, 4.169563, 4.172917]
    thicknesses = [210, 220, 230]

    # widths = np.array([0.4, 0.45, 0.5, 0.55, 0.6])
    # ngs = np.array([4.38215238, 4.27254985, 4.16956338, 4.13283219, 4.05791982])

    widths = np.array([0.495, 0.5, 0.505])
    neffs = np.array([2.40197253, 2.46586378, 2.46731758])
    ng = 4.2  # Group index of the waveguides

    for width, neff in zip(widths, neffs):
        p = ring(
            wl=wl,
            wl0=wl0,
            neff=neff,
            ng=ng,
            ring_length=ring_length,
            coupling=coupling,
            loss=loss,
        )
        plt.plot(wl, p, label=f"{int(width*1e3)}nm")

    plt.title("ring resonator vs waveguide width")
    plt.xlabel("wavelength (um)")
    plt.ylabel("Power Transmission")
    plt.grid()
    plt.legend()
    plt.show()

../_images/b39d441ebcacfdf1e9dc1418aed916b93777e3b3b398663dc99b0c678ea35399.png

Layout#

gdsfactory easily enables you to layout Component with as many levels of hierarchy as you need.

A Component is a canvas where we can add polygons, references to other components or ports.

Lets add two references in a component.

import toolz

c = gf.components.ring_single_heater(gap=0.2, radius=10, length_x=4)
c.plot()

../_images/a7d965f88df9c380e8d2c538ac5b9cbf740abbb7137796d1c4aee4b5ff336ec4.png

scene = c.to_3d()
scene.show()

Lets define a ring function that also accepts other component specs for the subcomponents (straight, coupler, bend)

ring = gf.components.ring_single_heater(
    gap=0.2, radius=10, length_x=4, via_stack_offset=(2, 0)
)
ring_with_grating_couplers = gf.routing.add_fiber_array(ring)
ring_with_grating_couplers.plot()

../_images/445d2b75727a601b27d3a2b1f018e3b679087d463e4e3dff9750e832d3131156.png

port_names = ["l_e1", "r_e3"]
port_names = ["l_e4", "r_e4"]
c = gf.routing.add_pads_top(
    ring,
    port_names=port_names,
)
c = gf.routing.add_fiber_array(c)
c

../_images/4a1900a81f63760245679da226f4371767fb6a20bc0560d1c1d3e354881eb680.png

Top reticle assembly#

Once you have your components and circuits defined, you can add them into a top reticle Component for fabrication.

You need to consider:

what design variations do you want to include in the mask? You need to define your Design Of Experiment or DOE
obey DRC (Design rule checking) foundry rules for manufacturability. Foundry usually provides those rules for each layer (min width, min space, min density, max density)
make sure you will be able to test te devices after fabrication. Obey DFT (design for testing) rules. For example, if your test setup works only for fiber array, what is the fiber array spacing (127 or 250um?)
if you plan to package your device, make sure you follow your packaging guidelines from your packaging house (min pad size, min pad pitch, max number of rows for wire bonding …)

nm = 1e-3
ring_te = toolz.compose(gf.routing.add_fiber_array, gf.components.ring_single)
rings_te = []

for radius in [10, 20, 50]:
    ring = gf.c.ring_single(radius=radius)
    ring_te = gf.routing.add_fiber_array(ring)
    ring_te.name = f"ring_{radius}"
    rings_te.append(ring_te)

rings = gf.grid(rings_te)


@gf.cell
def reticle(size=(1000, 1000)):
    c = gf.Component()
    r = c << rings
    m = c << gf.components.pack_doe(
        gf.components.mzi,
        settings=dict(delta_length=[100, 200]),
        function=gf.routing.add_fiber_array,
    )
    m.dxmin = r.dxmax + 10
    m.dymin = r.dymin
    c << gf.components.seal_ring(c)
    return c


m = reticle()
m

../_images/f03320311f460728f49ff4b148027ab0b803f4831bf4c87210ed6212919cb79f.png

nm = 1e-3
ring_te = toolz.compose(gf.routing.add_fiber_array, gf.components.ring_single)
gaps = [210 * nm, 220 * nm, 230 * nm]
rings = []
port_names = ["l_e4", "r_e4"]

for gap in gaps:
    ring = gf.c.ring_single_heater(gap=gap)
    ring_pads = gf.routing.add_pads_top(ring, port_names=port_names)
    ring_te = gf.routing.add_fiber_array(ring_pads)
    ring_te.name = f"ring_{gap}"
    rings.append(ring_te)


def reticle(size=(1000, 1000)):
    c = gf.Component()
    p = c << gf.pack(rings)[0]
    c.add_ports(p.ports)
    c << gf.components.seal_ring(c)
    return c


m = reticle()
m

../_images/778a13140f764ebcfd07407ab2c0dbc9e0f231c5f97017eac4dc72b4bbebb95e.png

gdspath = m.write_gds(gdspath="mask.gds")

m.pprint_ports()

┏━━━━━━━━━━━━━┳━━━━━━━┳━━━━━━━━━━━━━┳━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━┓
┃ name        ┃ width ┃ orientation ┃ layer       ┃ center                       ┃ port_type   ┃
┡━━━━━━━━━━━━━╇━━━━━━━╇━━━━━━━━━━━━━╇━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━┩
│ 0_o1        │ 10.0  │ 270.0       │ WG (1/0)    │ (145.02, 34.111000000000004) │ vertical_te │
│ 0_o2        │ 10.0  │ 270.0       │ WG (1/0)    │ (272.02, 34.111000000000004) │ vertical_te │
│ 0_l_e4      │ 80.0  │ 270.0       │ MTOP (49/0) │ (158.52, 179.101)            │ electrical  │
│ 0_r_e4      │ 80.0  │ 270.0       │ MTOP (49/0) │ (258.52, 179.101)            │ electrical  │
│ 0_l_e1      │ 4.0   │ 180.0       │ MTOP (49/0) │ (203.02, 151.101)            │ electrical  │
│ 0_l_e2      │ 4.0   │ 270.0       │ MTOP (49/0) │ (205.02, 149.101)            │ electrical  │
│ 0_l_e3      │ 4.0   │ 0.0         │ MTOP (49/0) │ (207.02, 151.101)            │ electrical  │
│ 0_r_e1      │ 4.0   │ 180.0       │ MTOP (49/0) │ (210.02, 151.101)            │ electrical  │
│ 0_r_e2      │ 4.0   │ 270.0       │ MTOP (49/0) │ (212.02, 149.101)            │ electrical  │
│ 0_r_e3      │ 4.0   │ 0.0         │ MTOP (49/0) │ (214.02, 151.101)            │ electrical  │
│ 0_loopback1 │ 10.0  │ 270.0       │ WG (1/0)    │ (18.02, 34.111000000000004)  │ vertical_te │
│ 0_loopback2 │ 10.0  │ 270.0       │ WG (1/0)    │ (399.02, 34.111000000000004) │ vertical_te │
│ 1_o1        │ 10.0  │ 270.0       │ WG (1/0)    │ (145.02, 298.161)            │ vertical_te │
│ 1_o2        │ 10.0  │ 270.0       │ WG (1/0)    │ (272.02, 298.161)            │ vertical_te │
│ 1_l_e4      │ 80.0  │ 270.0       │ MTOP (49/0) │ (158.52, 443.151)            │ electrical  │
│ 1_r_e4      │ 80.0  │ 270.0       │ MTOP (49/0) │ (258.52, 443.151)            │ electrical  │
│ 1_l_e1      │ 4.0   │ 180.0       │ MTOP (49/0) │ (203.02, 415.151)            │ electrical  │
│ 1_l_e2      │ 4.0   │ 270.0       │ MTOP (49/0) │ (205.02, 413.151)            │ electrical  │
│ 1_l_e3      │ 4.0   │ 0.0         │ MTOP (49/0) │ (207.02, 415.151)            │ electrical  │
│ 1_r_e1      │ 4.0   │ 180.0       │ MTOP (49/0) │ (210.02, 415.151)            │ electrical  │
│ 1_r_e2      │ 4.0   │ 270.0       │ MTOP (49/0) │ (212.02, 413.151)            │ electrical  │
│ 1_r_e3      │ 4.0   │ 0.0         │ MTOP (49/0) │ (214.02, 415.151)            │ electrical  │
│ 1_loopback1 │ 10.0  │ 270.0       │ WG (1/0)    │ (18.02, 298.161)             │ vertical_te │
│ 1_loopback2 │ 10.0  │ 270.0       │ WG (1/0)    │ (399.02, 298.161)            │ vertical_te │
│ 2_o1        │ 10.0  │ 270.0       │ WG (1/0)    │ (145.02, 562.21)             │ vertical_te │
│ 2_o2        │ 10.0  │ 270.0       │ WG (1/0)    │ (272.02, 562.21)             │ vertical_te │
│ 2_l_e4      │ 80.0  │ 270.0       │ MTOP (49/0) │ (158.52, 707.2)              │ electrical  │
│ 2_r_e4      │ 80.0  │ 270.0       │ MTOP (49/0) │ (258.52, 707.2)              │ electrical  │
│ 2_l_e1      │ 4.0   │ 180.0       │ MTOP (49/0) │ (203.02, 679.2)              │ electrical  │
│ 2_l_e2      │ 4.0   │ 270.0       │ MTOP (49/0) │ (205.02, 677.2)              │ electrical  │
│ 2_l_e3      │ 4.0   │ 0.0         │ MTOP (49/0) │ (207.02, 679.2)              │ electrical  │
│ 2_r_e1      │ 4.0   │ 180.0       │ MTOP (49/0) │ (210.02, 679.2)              │ electrical  │
│ 2_r_e2      │ 4.0   │ 270.0       │ MTOP (49/0) │ (212.02, 677.2)              │ electrical  │
│ 2_r_e3      │ 4.0   │ 0.0         │ MTOP (49/0) │ (214.02, 679.2)              │ electrical  │
│ 2_loopback1 │ 10.0  │ 270.0       │ WG (1/0)    │ (18.02, 562.21)              │ vertical_te │
│ 2_loopback2 │ 10.0  │ 270.0       │ WG (1/0)    │ (399.02, 562.21)             │ vertical_te │
└─────────────┴───────┴─────────────┴─────────────┴──────────────────────────────┴─────────────┘

You can also write the test sequence in CSV from the component

df = gf.labels.get_test_manifest(m)
df

	cell	measurement	measurement_settings	analysis	analysis_settings	doe
0	0_o1	None	None	None	None	None
1	0_o2	None	None	None	None	None
2	0_l_e4	None	None	None	None	None
3	0_r_e4	None	None	None	None	None
4	0_l_e1	None	None	None	None	None
5	0_l_e2	None	None	None	None	None
6	0_l_e3	None	None	None	None	None
7	0_r_e1	None	None	None	None	None
8	0_r_e2	None	None	None	None	None
9	0_r_e3	None	None	None	None	None
10	0_loopback1	None	None	None	None	None
11	0_loopback2	None	None	None	None	None
12	1_o1	None	None	None	None	None
13	1_o2	None	None	None	None	None
14	1_l_e4	None	None	None	None	None
15	1_r_e4	None	None	None	None	None
16	1_l_e1	None	None	None	None	None
17	1_l_e2	None	None	None	None	None
18	1_l_e3	None	None	None	None	None
19	1_r_e1	None	None	None	None	None
20	1_r_e2	None	None	None	None	None
21	1_r_e3	None	None	None	None	None
22	1_loopback1	None	None	None	None	None
23	1_loopback2	None	None	None	None	None
24	2_o1	None	None	None	None	None
25	2_o2	None	None	None	None	None
26	2_l_e4	None	None	None	None	None
27	2_r_e4	None	None	None	None	None
28	2_l_e1	None	None	None	None	None
29	2_l_e2	None	None	None	None	None
30	2_l_e3	None	None	None	None	None
31	2_r_e1	None	None	None	None	None
32	2_r_e2	None	None	None	None	None
33	2_r_e3	None	None	None	None	None
34	2_loopback1	None	None	None	None	None
35	2_loopback2	None	None	None	None	None

As you can see there are 6 devices with optical and electrical ports.

You can turn each label into a test manifest CSV file to interface with your lab instrumentation functions.

Each measurement will use a different measurement procedure and settings measurement_settings

The default measurement settings for each functions can also be defined in a separate CSV file and easily editable with Excel or LibreOffice.

df.to_csv("test_manifest.csv")

from functools import partial

add_fiber_array_optical_south_electrical_north = partial(
    gf.components.add_fiber_array_optical_south_electrical_north,
    pad=gf.c.pad,
    grating_coupler=gf.c.grating_coupler_te,
    cross_section_metal="metal_routing",
)


def sample_reticle(grid: bool = False, **kwargs) -> gf.Component:
    """Returns MZI with TE grating couplers.

    Args:
        grid: if True returns components on a regular grid. False packs them as close as possible.
        kwargs: passed to pack or grid.
    """
    test_info_mzi_heaters = dict(
        doe="mzis_heaters",
        analysis="mzi_heater",
        measurement="optical_loopback4_heater_sweep",
    )
    test_info_ring_heaters = dict(
        doe="ring_heaters",
        analysis="ring_heater",
        measurement="optical_loopback2_heater_sweep",
    )
    spiral_info = dict(
        doe="spirals_sc",
        measurement="optical_loopback4",
        analysis="optical_loopback4_spirals",
    )

    mzis = []
    rings = []
    spirals = []

    for length in [100, 200, 300]:
        mzi = gf.components.mzi2x2_2x2_phase_shifter(
            length_x=length, auto_rename_ports=False
        )
        mzi = add_fiber_array_optical_south_electrical_north(
            mzi,
            electrical_port_names=["top_l_e2", "top_r_e2"],
        )
        mzi.name = f"mzi_heater_{length}"
        mzi.info.update(test_info_mzi_heaters)
        mzis.append(mzi)

    for length_x in [10, 20, 30]:
        ring = gf.components.ring_single_heater(length_x=length_x)
        ring = add_fiber_array_optical_south_electrical_north(
            ring,
            electrical_port_names=["l_e2", "r_e2"],
        )
        ring.info.update(test_info_ring_heaters)
        ring.name = f"ring_single_heater_{length_x}"
        rings.append(ring)

    for length in [0, 100, 200]:
        spiral = gf.c.spiral(length=length)
        spiral = gf.routing.add_fiber_array(spiral)
        spiral.name = f"spiral_{length}"
        spiral.info.update(spiral_info)
        spirals.append(spiral)

    components = mzis + rings + spirals

    if grid:
        return gf.grid(components, name_ports_with_component_name=True, **kwargs)
    c = gf.pack(components, **kwargs)
    if len(c) > 1:
        raise ValueError(f"failed to pack into single group. Made {len(c)} groups.")
    return c[0]


m = sample_reticle()
m

../_images/16b3932b836427c4a956a13d7a5f05f42428868c9e9ee330d904008448ec540b.png

m.pprint_ports()

┏━━━━━━━━━━━━━┳━━━━━━━┳━━━━━━━━━━━━━┳━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━┓
┃ name        ┃ width ┃ orientation ┃ layer       ┃ center                        ┃ port_type   ┃
┡━━━━━━━━━━━━━╇━━━━━━━╇━━━━━━━━━━━━━╇━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━┩
│ 0_e4_1_1    │ 100.0 │ 270.0       │ MTOP (49/0) │ (285.52, 255.05)              │ electrical  │
│ 0_e4_1_2    │ 100.0 │ 270.0       │ MTOP (49/0) │ (385.52, 255.05)              │ electrical  │
│ 1_e4_1_1    │ 100.0 │ 270.0       │ MTOP (49/0) │ (285.52, 615.0500000000001)   │ electrical  │
│ 1_e4_1_2    │ 100.0 │ 270.0       │ MTOP (49/0) │ (385.52, 615.0500000000001)   │ electrical  │
│ 2_e4_1_1    │ 100.0 │ 270.0       │ MTOP (49/0) │ (285.52, 975.0500000000001)   │ electrical  │
│ 2_e4_1_2    │ 100.0 │ 270.0       │ MTOP (49/0) │ (385.52, 975.0500000000001)   │ electrical  │
│ 3_e4_1_1    │ 100.0 │ 270.0       │ MTOP (49/0) │ (829.46, 255.05)              │ electrical  │
│ 3_e4_1_2    │ 100.0 │ 270.0       │ MTOP (49/0) │ (929.46, 255.05)              │ electrical  │
│ 4_e4_1_1    │ 100.0 │ 270.0       │ MTOP (49/0) │ (829.46, 615.0500000000001)   │ electrical  │
│ 4_e4_1_2    │ 100.0 │ 270.0       │ MTOP (49/0) │ (929.46, 615.0500000000001)   │ electrical  │
│ 5_e4_1_1    │ 100.0 │ 270.0       │ MTOP (49/0) │ (829.46, 975.0500000000001)   │ electrical  │
│ 5_e4_1_2    │ 100.0 │ 270.0       │ MTOP (49/0) │ (929.46, 975.0500000000001)   │ electrical  │
│ 6_o1        │ 10.0  │ 270.0       │ WG (1/0)    │ (209.298, 1114.111)           │ vertical_te │
│ 6_o2        │ 10.0  │ 270.0       │ WG (1/0)    │ (336.298, 1114.111)           │ vertical_te │
│ 6_loopback1 │ 10.0  │ 270.0       │ WG (1/0)    │ (82.298, 1114.111)            │ vertical_te │
│ 6_loopback2 │ 10.0  │ 270.0       │ WG (1/0)    │ (463.298, 1114.111)           │ vertical_te │
│ 7_o1        │ 10.0  │ 270.0       │ WG (1/0)    │ (626.24, 1114.111)            │ vertical_te │
│ 7_o2        │ 10.0  │ 270.0       │ WG (1/0)    │ (753.24, 1114.111)            │ vertical_te │
│ 7_loopback1 │ 10.0  │ 270.0       │ WG (1/0)    │ (499.24, 1114.111)            │ vertical_te │
│ 7_loopback2 │ 10.0  │ 270.0       │ WG (1/0)    │ (880.24, 1114.111)            │ vertical_te │
│ 8_o1        │ 10.0  │ 270.0       │ WG (1/0)    │ (1043.18, 1114.111)           │ vertical_te │
│ 8_o2        │ 10.0  │ 270.0       │ WG (1/0)    │ (1170.18, 1114.111)           │ vertical_te │
│ 8_loopback1 │ 10.0  │ 270.0       │ WG (1/0)    │ (916.1800000000001, 1114.111) │ vertical_te │
│ 8_loopback2 │ 10.0  │ 270.0       │ WG (1/0)    │ (1297.18, 1114.111)           │ vertical_te │
└─────────────┴───────┴─────────────┴─────────────┴───────────────────────────────┴─────────────┘

df = gf.labels.get_test_manifest(m)
df

	cell	measurement	measurement_settings	analysis	analysis_settings	doe
0	0_e4_1_1	None	None	None	None	None
1	0_e4_1_2	None	None	None	None	None
2	1_e4_1_1	None	None	None	None	None
3	1_e4_1_2	None	None	None	None	None
4	2_e4_1_1	None	None	None	None	None
5	2_e4_1_2	None	None	None	None	None
6	3_e4_1_1	None	None	None	None	None
7	3_e4_1_2	None	None	None	None	None
8	4_e4_1_1	None	None	None	None	None
9	4_e4_1_2	None	None	None	None	None
10	5_e4_1_1	None	None	None	None	None
11	5_e4_1_2	None	None	None	None	None
12	6_o1	None	None	None	None	None
13	6_o2	None	None	None	None	None
14	6_loopback1	None	None	None	None	None
15	6_loopback2	None	None	None	None	None
16	7_o1	None	None	None	None	None
17	7_o2	None	None	None	None	None
18	7_loopback1	None	None	None	None	None
19	7_loopback2	None	None	None	None	None
20	8_o1	None	None	None	None	None
21	8_o2	None	None	None	None	None
22	8_loopback1	None	None	None	None	None
23	8_loopback2	None	None	None	None	None

Ring filter

Contents

Ring filter#

Calculations#

Layout#

Top reticle assembly#