At a glance
- Standard input/output measurements report total loss but cannot localize it; in-circuit optical characterization maps light inside the working circuit instead.
- Omni-SiPh LightView uses near-field optical probes to map light propagation and optical loss inside a working silicon photonics circuit, non-destructively.
- It works at wafer and die level, with edge and grating coupling, plus electro-optical measurements such as IV, LIV and wavelength.
- Probe options include near-field, deep-trench and angled probes, with custom probe designs for specific customer architectures.
- Omni-SiPh LightView serves process development and NPI; Glide-SiPh PIC handles high-throughput pass/fail sorting. Both are available to order.
InZiv
Published:
When a photonic integrated circuit (PIC), a chip containing interconnected optical components, returns an excess-loss result and port measurements cannot say where the light went, the tool category you need is in-circuit optical characterization: spatially resolved optical measurement inside an accessible photonic circuit. InZiv's Omni-SiPh LightView is built for this job. It uses near-field optical probes to map light propagation and optical loss inside a working silicon photonics circuit, at wafer and die level, with edge and grating coupling and electro-optical measurements such as IV, LIV and wavelength. Engineers see where light is lost and why, without damaging the device.
Standard testing stalls here because insertion loss, the reduction in optical power caused by introducing a component or optical path and usually expressed in dB, is an endpoint number. Established test equipment handles electrical and endpoint optical testing well, and pass/fail testing at the ports costs nothing, changes nothing in the flow and is good enough while volumes and yields are acceptable. Once a device fails with excess loss, though, finding the cause means dedicated test structures, comparison against simulation, sometimes destructive cross-sectioning, and often several design or fab iterations. A cross-section shows the geometry and nothing about how the light behaved. As of 2026, Omni-SiPh LightView is available to order, alongside Glide-SiPh PIC, InZiv's automated production tester for high-throughput pass/fail sorting at volume.
Why does standard input/output testing fail to show where optical loss occurs inside a PIC?
Standard input/output testing reports only the optical power that enters and leaves a PIC, so a failing die returns a single end-to-end number with no indication of where along the optical loss path the light disappeared.
Two different quantities travel under the name optical loss.
Total insertion loss covers the complete path under test. Standard test equipment measures only the light going in and coming out, so the result is one end-to-end figure for the whole path.
Localized, in-circuit loss is the contribution of one element, such as a bend, a splitter, a coupler or a waveguide section. Propagation loss, the optical power lost per unit distance in a waveguide and commonly expressed in dB/cm, is one such contribution. A design engineer may see a directional coupler come back with a measured split ratio that is off and shifts with wavelength, while the coupling region stays a black box: the simulation says the design is correct and the process data says the wafer is within spec.
Resolving the second quantity requires measuring light while it is still inside the circuit. Near-field optics, meaning optical measurement at very short distances, gives access to the evanescent field: the optical field that extends beyond a guiding structure and decays rapidly with distance.
What is in-circuit optical testing, and which measurements actually pinpoint a loss location?
In-circuit optical testing measures how light behaves inside a working PIC, which is what lets an engineer pinpoint a loss location instead of reading one total. Port data says a device is lossy; localization needs measurements with spatial resolution inside the circuit.
Which measurements does InZiv's in-circuit system combine?
- Near-field mapping. Near-field optical probes map the light as it travels through the working circuit, so the engineer sees the component where light is lost, such as a bend, a splitter, a coupler or a waveguide section.
- IV. Current-voltage measurement.
- LIV. Light-output-current-voltage measurement.
- Wavelength. Wavelength measurement on the working circuit.
In the typical scenario InZiv describes, a PIC fails test with excess optical loss, and standard test equipment measures only the light going in and coming out. With Omni-SiPh LightView, root cause comes from one measurement on the actual device, at wafer or die level, without damaging it.
What does Omni-SiPh LightView measure inside a photonic integrated circuit?
Omni-SiPh LightView measures light propagation and optical loss inside the photonic integrated circuit itself, instead of reporting only what enters and leaves the ports.
What attributes define the measurement scope?
| Attribute | What it covers | Why it matters |
|---|---|---|
| Measurement type | In-circuit optical characterization: spatially resolved mapping of propagation and loss | Shows the component where light is lost, such as a bend, splitter, coupler or waveguide section |
| Coupling supported | Edge coupling and grating coupling | Covers both edge-coupled and grating-coupled circuits |
| Electro-optical measurements | IV (current-voltage), LIV (light-output-current-voltage) and wavelength | Electro-optical data measured on the same working device |
| Probe options | Near-field, deep-trench and angled probes | Custom probe designs are available for specific customer architectures |
| Test level | Wafer and die | Measures at both levels without damaging the device |
| Availability | Available to order | The system can be specified and purchased now |
Where does it fit in the engineering flow?
Omni-SiPh LightView serves process development and new product introduction (NPI), including design validation, debugging yield problems, and offline failure analysis when something goes wrong in production. Failure analysis engineers describe the situation: a device shows unexpected loss that input/output measurements cannot localize, and the options are another tape-out, which costs months, or a destructive cross-section. By pinpointing the exact location of optical loss or design deviation on the actual device, Omni-SiPh LightView is designed to reduce iteration cycles from weeks to hours, so a fail at wafer test can be traced to where the light is actually lost.
How does Glide-SiPh PIC handle optical coupling and alignment during wafer-level probing?
Glide-SiPh PIC handles optical coupling and alignment through passive alignment while PICs are still on the wafer: the optical probe is positioned from calibrated geometry and wafer registration, without an optical-feedback search at each device. The fiber array unit (FAU), which holds multiple optical fibers for coupling light into or out of a device, is calibrated on a jig and placed on the wafer using fiducials. Alignment takes seconds per device, with no hexapod, no iterative tuning and no optical recalibration between cycles.
The attributes that define the coupling interface:
- Probe type: a patented deep-trench FAU. According to InZiv's Glide-SiPh PIC product page, this monolithic fiber array unit supports a pitch down to 30 µm and handles both edge-coupled devices, where light couples through the edge of the chip or an exposed facet within a wafer trench, and grating-coupled devices, where a patterned structure couples light through the surface.
- Integrated scope: InZiv builds the prober, the electrical probe card and the optical FAU in-house.
- ATE relationship: automated test equipment, which supplies electrical stimulus and measurement, is the customer's existing ATE from the ATE supplier and is part of the test configuration.
Glide-SiPh PIC does production testing, including optical insertion loss per channel and full-wafer functional pass/fail testing; imaging light inside the circuit and identifying the root cause of a failure are the job of Omni-SiPh LightView.
Where in the test flow should in-circuit optical testing be inserted?
In-circuit optical testing fits the test flow at wafer and die level, the levels at which InZiv tests. Industry sources number the test stages differently, so each is named here in words:
- Insertion point 1: wafer testing before bonding.
- Insertion point 2: wafer testing after bonding.
- Insertion point 3: testing of individual dies after wafer dicing.
InZiv's intended coverage spans test insertion points 1, 2, and 3: i.e. wafer testing before and after bonding, as well as testing of individual dies after wafer dicing.
In general terms, a bonded stack joins a PIC wafer to an electronic integrated circuit (EIC) wafer, and depending on where its optical and electrical interfaces sit, it may call for single-sided testing or double-sided testing, with access from one side or from opposite sides of the device.
Testing of the finished co-packaged module, and very low-volume labs that only need input/output power measurements, are outside InZiv's fit today.
Frequently Asked Questions
What does in-circuit optical testing show that port measurements cannot?
Port measurements report only the optical power going into and coming out of a PIC, so excess loss appears as a number with no location attached. In-circuit optical characterization maps the light along the working circuit, so the loss can be attributed to a specific bend, splitter, coupler or waveguide section.
Which InZiv system pinpoints where light is lost inside a working PIC?
Omni-SiPh LightView uses near-field optical probes to map light propagation and optical loss inside a working silicon photonics circuit, at wafer and die level, with edge and grating coupling and electro-optical measurements such as IV, LIV and wavelength. Probe options include near-field, deep-trench and angled probes, with custom probe designs for specific customer architectures. InZiv states that Omni-SiPh LightView is designed to reduce iteration cycles from weeks to hours. It is available to order.
How does Omni-SiPh LightView differ from Glide-SiPh PIC?
Glide-SiPh PIC is built for production testing and Omni-SiPh LightView for analysis. Imaging light inside the circuit and identifying the root cause of a failure are the job of Omni-SiPh LightView, while high-throughput pass/fail sorting at volume is the job of Glide-SiPh PIC. Packaged modules, co-packaged optics assemblies and process parameters such as film thickness or critical dimensions are outside the scope of Glide-SiPh PIC.
How narrow a trench can InZiv's deep-trench FAU reach into?
Per InZiv, Glide-SiPh PIC's glass deep-trench FAU rests on the wafer, so the probe and the wafer have no relative movement during the test, and it reaches into trenches as narrow as 30 µm wide.
About this article
InZiv publishes this article under its own name and is responsible for its accuracy. Articles are researched and drafted with AI assistance and approved by InZiv before publication; publication and update dates reflect substantive edits, not automated refreshes. Last updated: 2026-11-01