{
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"source": [
"# Circuit from YAML\n",
"> Sometimes it's useful to be able to define circuits from YAML definitions. To not re-invent the wheel, SAX uses [GDSFactory](https://gdsfactory.readthedocs.io/en/latest/yaml.html)'s YAML netlist spec to define its circuits. This makes it very easy to convert a GDSFactory layout to a SAX circuit model!"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "1",
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"source": [
"import jax.numpy as jnp\n",
"import matplotlib.pyplot as plt\n",
"import sax\n",
"import yaml"
]
},
{
"cell_type": "markdown",
"id": "2",
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"source": [
"## MZI"
]
},
{
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"source": [
"Let's first see how we can define a SAX circuit from YAML:"
]
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"source": [
"netlist = \"\"\"\n",
"instances:\n",
" lft:\n",
" component: coupler\n",
" settings:\n",
" coupling: 0.5\n",
" rgt:\n",
" component: coupler\n",
" settings:\n",
" coupling: 0.5\n",
" top:\n",
" component: straight\n",
" settings:\n",
" length: 25.0\n",
" btm:\n",
" component: straight\n",
" settings:\n",
" length: 15.0\n",
"\n",
"connections:\n",
" lft,out0: btm,in0\n",
" btm,out0: rgt,in0\n",
" lft,out1: top,in0\n",
" top,out0: rgt,in1\n",
"\n",
"ports:\n",
" in0: lft,in0\n",
" in1: lft,in1\n",
" out0: rgt,out0\n",
" out1: rgt,out1\n",
"\n",
"\"\"\""
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "5",
"metadata": {
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"tags": []
},
"outputs": [],
"source": [
"yaml.safe_load(netlist)"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "6",
"metadata": {
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"end_time": "2025-02-27T06:29:39.188959",
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"outputs": [],
"source": [
"mzi, _ = sax.circuit(\n",
" yaml.safe_load(netlist),\n",
" models={\"coupler\": sax.models.coupler, \"straight\": sax.models.straight},\n",
")"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "7",
"metadata": {
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"outputs": [],
"source": [
"wl = jnp.linspace(1.5, 1.6, 1000)\n",
"transmission = jnp.abs(mzi(wl=wl)[\"in0\", \"out0\"]) ** 2\n",
"\n",
"plt.plot(wl * 1e3, transmission)\n",
"plt.xlabel(\"λ [nm]\")\n",
"plt.ylabel(\"T\")\n",
"plt.show()"
]
},
{
"cell_type": "markdown",
"id": "8",
"metadata": {
"papermill": {
"duration": 0.008232,
"end_time": "2025-02-27T06:29:40.562047",
"exception": false,
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},
"source": [
"That was easy! However, during the above YAML conversion, only models available in `sax.models` were used. What if we want to map the YAML component names to custom models? Let's say we want to use a dispersionless waveguide for the above model for example:"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "9",
"metadata": {
"papermill": {
"duration": 0.015512,
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"source": [
"def waveguide_without_dispersion(wl=1.55, length=25.0, neff=2.34):\n",
" phase = 2 * jnp.pi * neff * length / wl\n",
" sdict = sax.reciprocal({(\"in0\", \"out0\"): jnp.exp(1j * phase)})\n",
" return sdict"
]
},
{
"cell_type": "markdown",
"id": "10",
"metadata": {
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"duration": 0.004785,
"end_time": "2025-02-27T06:29:40.595274",
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"source": [
"We can regenerate the above circuit again, but this time we specify a models mapping:"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "11",
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"outputs": [],
"source": [
"mzi, _ = sax.circuit(\n",
" yaml.safe_load(netlist),\n",
" models={\"straight\": waveguide_without_dispersion, \"coupler\": sax.models.coupler},\n",
")"
]
},
{
"cell_type": "markdown",
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"source": [
"> The `models=` keyword in `circuit_from_yaml` can be a dictionary **or** an imported python module (like for example `sax.models`). Or a list containing multiple of such dictionary mappings and imported modules."
]
},
{
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"source": [
"wl = jnp.linspace(1.5, 1.6, 1000)\n",
"transmission = jnp.abs(mzi(wl=wl)[\"in0\", \"out0\"]) ** 2\n",
"\n",
"plt.plot(wl, transmission)\n",
"plt.xlabel(\"Wavelength [nm]\")\n",
"plt.ylabel(\"T\")\n",
"plt.show()"
]
}
],
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