# Version 0.2 (draft)¶

A file conforming to the openEPDA MDF format has the following structure. The first line is a format identifier, # openEPDA MDF. After this, the data section follows, which adheres to the YAML format, and contains all settings (numeric and textual) data in the form of an associative array.

An example of a file recorded in the openEPDA MDF format is shown below.

## Attributes¶

In this section, a list and explanation of the attributes is given. Additional attributes which are not listed below are not allowed.

### Required¶

The following keys are required to be present in the MDF:

• _openEPDA: an object defining the format and its version.

• mdf: a string with a unique identifier of the MDF

• cell: a string with an identifier of the PIC design to be measured

• die_rotation: an angle for die position on the setup. It determines the orientation of the die, e.g. west-to-left or west-to-right.

• measurements: Definition of the measurements used in the file. A measurement includes the measurement module and its settings. Key is the name of the measurement, value is a dictionary with measurement module name and settings (see Note 4).

• reference: A list of reference circuits. Each list element is a dictionary: key is a reference port label, value is a dictionary {side: port}.

• measurement_sequence: Each list element is a measurement group. A measurement group is a list of dictionaries, each describing a set of individual observation on a single circuit.

### Notes¶

1. All the above attributes are obligatory to be present in an MDF in order to be used. Otherwise MDF reader should return an error of incorrect MDF format.

2. There must be two reference circuits defined, each containing one east and west port.

3. For each circuit to be measured, two ports maximum can be used at the same time, and they must be on the opposite sides of the chip (this comes from a hardware restrictions of the current setup). The ports for a circuit are grouped by the side, and their combinations are generated based on settings in measurements key.

4. The measurements key contains a dictionary of the measurements that are intended to be used in the MDF. The names for these can be arbitrary (mmi_perm in the example) and they are referenced later on in the measurement_sequence part. The value contains a dictionary with required keys measurement_module and measurement_module_settings.

5. Measurement module name is a valid class which describes the algorithm performing the measurements. A measurement module can be standard or a user-defined. See the list of standard modules with their parameters in the next section.

6. The measurement_sequence tag contains a list of measurement groups. Each measurement group is identified by its label (top_mmi in the example) and contains a list of observations sets. In the example, the group top_mmi contains two measurement sets, each set determined by the mmi_perm measurement name.

7. Each dictionary describing an observation set must contain the following keys:

• measurement

• west_ports

• east_ports

The in_ports and out_ports keys can be either single port or lists of ports. The combinations of these to be actually used in the measurement are determined by in the measurements section.

8. Comments are standard YAML comments, they start with a hashtag symbol and can be placed at the end of any line. E.g., # This is a comment.

## Example MDF file¶

# openEPDA MDF
_openEPDA:
format: openEPDA-MDF
version: "0.2"

mdf: mmi_measurement_full_v1
cell: SP19-3-4
die_rotation: 0
input_rotated: True

measurements:
mmi_perm:
measurement_module: FastScan5
measurement_module_settings:
source: Tunable_laser
detector: Powermeter
wvl_sweep: [1450, 1630]
sweep_speed: 5 # nm/s
sweep_wvl_step: 0.01 # nm
pol: [TE, TM]
ports: product_min

Reference:
- ref_south:
left: ioW008
right: ioE012
- ref_north:
left: ioW298
right: ioE302

measurement_sequence:
- top_mmi:
- {measurement: mmi_perm, west_ports: [ioW292, ioW290], east_ports: [ioE296, ioE294]}
- {measurement: mmi_perm, west_ports: [ioW302, ioW304], east_ports: [ioE306, ioE308]}