DCT
2:21-cv-00378
Viavi Solutions Inc v. Zhejiang Crystal Optech Co Ltd
Key Events
Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Viavi Solutions Inc. (Delaware)
- Defendant: ZHEJIANG CRYSTAL-OPTECH CO LTD. (China)
- Plaintiff’s Counsel: Venable LLP
- Case Identification: 2:21-cv-00378, E.D. Tex., 10/07/2021
- Venue Allegations: Venue is alleged on the basis that the defendant is a foreign corporation that does not reside in the United States and therefore may be sued in any judicial district. The complaint further alleges that the defendant purposefully availed itself of the district by delivering its products into the stream of commerce with the knowledge and expectation that they would be incorporated into end-products sold in Texas.
- Core Dispute: Plaintiff alleges that Defendant’s optical filters, supplied for use in 3D motion sensing modules in consumer electronics, infringe patents related to optical filter designs that use hydrogenated silicon layers.
- Technical Context: The technology concerns advanced near-infrared optical filters designed to improve performance and reduce thickness, which is critical for 3D sensing applications like facial and gesture recognition in compact devices such as smartphones.
- Key Procedural History: The complaint alleges that other industry participants have licensed the asserted technology from the plaintiff. It also alleges that the defendant received pre-suit notification of infringement in July 2021. Subsequent to the filing of this complaint, all asserted claims (1-19) of U.S. Patent No. 11,131,794 were cancelled in an inter partes review proceeding (IPR2022-01489), a development which will significantly narrow the scope of the present litigation.
Case Timeline
| Date | Event |
|---|---|
| 2012-07-16 | Priority Date for ’269, ’526, and ’794 Patents |
| 2017-03-07 | U.S. Patent No. 9,588,269 Issued |
| 2019-03-05 | U.S. Patent No. 10,222,526 Issued |
| 2021-07-01 | Alleged Pre-Suit Notice of Infringement to Defendant |
| 2021-09-28 | U.S. Patent No. 11,131,794 Issued |
| 2021-10-07 | Complaint Filed |
| 2022-09-06 | IPR Filed Against ’794 Patent (IPR2022-01489) |
| 2024-11-12 | IPR Certificate Issued Cancelling Claims of ’794 Patent |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 9,588,269 - "Optical Filter and Sensor System", Issued March 7, 2017
The Invention Explained
- Problem Addressed: The patent describes conventional optical filters used in 3D sensing and gesture-recognition systems as suffering from a key deficiency: the center wavelength of their passband shifts significantly depending on the angle of the incoming light (’269 Patent, col. 2:7-12). To compensate, these filters must have wide passbands, which allows more unwanted ambient light to reach the sensor, thereby reducing the system's signal-to-noise ratio. Furthermore, these conventional filters require a large number of material layers, making them thick, expensive, and difficult to manufacture (’269 Patent, col. 2:13-20).
- The Patented Solution: The invention proposes using a different material—hydrogenated silicon (Si:H)—for the high-refractive-index layers in the filter stack (’269 Patent, Abstract). This material enables the design of a filter that is significantly thinner and, critically, exhibits a much smaller shift in its passband's center wavelength as the angle of incidence changes, which improves overall system performance by better rejecting ambient light (’269 Patent, col. 2:21-27; col. 8:31-38).
- Technical Importance: This innovation allowed for the creation of thinner, more cost-effective, and higher-performance optical filters, a key enabling technology for integrating 3D sensing capabilities into the compact form factor of consumer electronics (’269 Patent, col. 2:15-20).
Key Claims at a Glance
- The complaint asserts independent claim 1 (Compl. ¶25).
- The essential elements of independent claim 1 are:
- An optical filter comprising a filter stack.
- The filter stack has a plurality of thin film hydrogenated silicon layers with a refractive index greater than 3 over a wavelength range of 800 to 1100 nm.
- The filter stack also has a plurality of thin film dielectric lower-refractive-index layers with a refractive index less than 3 over the same wavelength range.
- The hydrogenated silicon layers and the lower-refractive-index layers alternate in a one-to-one ratio.
- The filter exhibits interference that creates a passband at least partially overlapping the 800 to 1100 nm wavelength range.
- The passband's center wavelength shifts by less than 20 nm in magnitude with a change in incidence angle between 0° and 30°.
U.S. Patent No. 10,222,526 - "Optical Filter and Sensor System", Issued March 5, 2019
The Invention Explained
- Problem Addressed: This patent, part of the same family as the ’269 patent, addresses the identical technical problem of conventional oxide-based optical filters being too thick, expensive, and susceptible to performance degradation from large shifts in their passband with changing light incidence angles (’526 Patent, col. 2:5-20).
- The Patented Solution: The solution is also the use of an improved hydrogenated silicon (Si:H) material for the high-refractive-index layers. The patent details how this material, which possesses both a high refractive index and a low extinction coefficient in the near-infrared spectrum, can be used to construct a filter with a reduced number of layers and superior "angle-shift" performance (’526 Patent, Abstract; col. 2:21-30).
- Technical Importance: By enabling thinner filters with more stable performance across various angles, this technology facilitates the design of more robust and compact 3D sensing modules suitable for mass-market consumer devices (’526 Patent, col. 2:15-20).
Key Claims at a Glance
- The complaint asserts independent claim 27 (Compl. ¶32).
- The essential elements of independent claim 27 are:
- An optical filter comprising a plurality of layers.
- These layers include hydrogenated silicon layers and lower-refractive-index layers.
- The optical filter has a passband.
- The passband has a center wavelength that shifts by less than 13 nm in magnitude with a change in an incidence angle from 0° to 30°.
U.S. Patent No. 11,131,794 - "Optical Filter and Sensor System", Issued September 28, 2021
Technology Synopsis
This patent also addresses the angle-shift, thickness, and cost problems of conventional optical filters for 3D sensing systems (’794 Patent, col. 2:5-20). It discloses an optical filter using alternating layers of hydrogenated silicon and a lower-refractive-index material to achieve a narrow passband with a small center-wavelength shift, enabling thinner and higher-performance filters (’794 Patent, Abstract; col. 2:25-34).
Asserted Claims
The complaint asserts independent claim 9 (Compl. ¶39).
Accused Features
The accused filter is alleged to comprise a set of layers including silicon and hydrogen, another set of layers including oxygen, and a near-infrared bandpass filter whose center wavelength shifts by less than 15 nm with an incidence angle change from 0° to 30° (Compl. ¶40).
III. The Accused Instrumentality
Product Identification
The "Crystal Infringing Filter" (Compl. ¶10).
Functionality and Market Context
- The accused products are described as "low angle shift optical filters that employ hydrogenated silicon layers as a high refractive index layer" (Compl. ¶10). These filters are components designed for 3D motion sensing modules, which Samsung reportedly refers to as "Time of Flight" or "ToF" modules (Compl. ¶12).
- The complaint alleges that Defendant Crystal is a "direct supplier" of these optical filters to Samsung Electronics for incorporation into mobile devices, such as the Samsung Galaxy S20 and Note 10+ mobile phones, which are sold in the United States (Compl. ¶¶11-13).
IV. Analysis of Infringement Allegations
No probative visual evidence provided in complaint. The complaint references "Exhibit 2" for detailed infringement analysis, but this exhibit was not available for review. The following summary is based on the narrative allegations in the complaint body.
’269 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| An optical filter comprising a filter stack | Crystal's Infringing Filter is an optical filter comprising a filter stack. | ¶26 | col. 5:7-8 |
| a plurality of thin film hydrogenated silicon layers that have a refractive index greater than 3 over a wavelength range of 800 to 1100 nm | The filter stack has a plurality of thin film hydrogenated silicon layers that have a refractive index greater than 3 over a wavelength range of 800 to 1100 nm. | ¶26 | col. 5:25-30 |
| a plurality of thin film dielectric lower-refractive-index layers that have a refractive index less than 3 over the wavelength range of 800 to 1100 nm | The stack has a plurality of thin film lower refractive index layers that have a refractive index less than 3 over the wavelength range of 800 to 1100 nm. | ¶26 | col. 5:50-54 |
| wherein the plurality of thin film dielectric lower-refractive-index layers alternate, in a one-to-one ratio, with the plurality of thin film hydrogenated silicon layers | The plurality of thin film lower refractive index layers alternate, in a one-to-one ratio, with the plurality of thin film hydrogenated silicon layers. | ¶26-27 | col. 10:43-47 |
| exhibits interference that creates a passband that at least partially overlaps with the wavelength range of 800 to 1100 nm | The filter additionally exhibits interference that creates a passband that at least partially overlaps with the wavelength range of 800 to 1100 nm. | ¶27 | col. 10:48-51 |
| and the passband has a center wavelength that shifts by less than 20 nm in magnitude with a change in an incidence angle between 0° and 30° | The passband has a center wavelength that shifts by less than 20 nm in magnitude with a change in an incidence angle between 0° and 30°. | ¶27 | col. 10:51-54 |
’526 Patent Infringement Allegations
| Claim Element (from Independent Claim 27) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| An optical filter, comprising a plurality of layers | Crystal's Infringing Filter comprises a plurality of layers. | ¶33 | col. 12:35-36 |
| wherein the plurality of layers include hydrogenated silicon layers and lower-refractive-index layers | The layers...include hydrogenated silicon layers and lower refractive index layers. | ¶33 | col. 12:37-39 |
| and wherein the optical filter has a passband that has a center wavelength that shifts by less than 13 nm in magnitude with a change in an incidence angle from 0° to 30° | The filter has a passband that has a center wavelength that shifts by less than 13 nm in magnitude with a change in an incidence angle between 0° and 30°. | ¶33 | col. 12:39-43 |
Identified Points of Contention
- Scope Questions: A primary point of contention may be whether the accused filters meet the specific numerical limitations of the claims. This raises the question of whether discovery and testing will confirm that the filters have hydrogenated silicon layers with a refractive index "greater than 3," and whether the "center wavelength" shift is verifiably "less than 20 nm" (’269 Patent) or "less than 13 nm" (’526 Patent) under the specified conditions.
- Technical Questions: The complaint's allegations are conclusory, referencing an external exhibit for proof. A technical question for the court will be what evidence supports the assertion that the accused filters meet these precise performance metrics. The method of measuring the "center wavelength" and calculating its "shift" could also become a point of technical debate.
V. Key Claim Terms for Construction
The Term: "hydrogenated silicon layers"
Context and Importance
This term is the technological core of the asserted patents, as the unique properties of this material are what allegedly enable the superior performance (reduced angle-shift). The definition of what constitutes a "hydrogenated silicon layer" will be critical for determining the scope of the claims. Practitioners may focus on this term because its construction could determine whether only filters made with a specific, high-performance variant of Si:H infringe, or if a broader class of materials is covered.
Intrinsic Evidence for Interpretation
- Evidence for a Broader Interpretation: The specification introduces the material generally as "hydrogenated silicon (Si:H)" produced by sputtering a silicon target in the presence of hydrogen, without limiting it to a single chemical formula or manufacturing process (’526 Patent, col. 4:20-22, 4:41-47).
- Evidence for a Narrower Interpretation: The detailed description provides specific examples of producing the material using pulsed DC sputtering with a plasma activation source (PAS) and particular hydrogen flow rates, deposition rates, and post-coating annealing steps, which are described as important for achieving the desired optical properties (’526 Patent, col. 4:31-67, col. 5:1-25). A party could argue these process details are required to achieve the invention and should limit the claim's scope.
The Term: "center wavelength that shifts by less than [X] nm"
Context and Importance
This limitation quantifies the primary benefit of the invention—reduced angle-shift. The infringement analysis for all asserted patents hinges on whether the accused filters meet these specific numerical thresholds (e.g., <20 nm for the ’269 patent, <13 nm for the ’526 patent). The precise methodology for measuring this shift is not defined in the claims themselves.
Intrinsic Evidence for Interpretation
- Evidence for a Broader Interpretation: The claims do not specify a test methodology, suggesting that any standard, art-recognized method for determining the center wavelength of a passband and its shift would be appropriate.
- Evidence for a Narrower Interpretation: The patents include numerous figures (e.g., ’526 Patent, Figs. 7D, 8C, 9B) that plot transmission spectra at different angles. A party might argue that these exemplary plots implicitly define how the "center wavelength" is determined (e.g., as the midpoint of the full width at half maximum) and how the "shift" is calculated, potentially narrowing the range of acceptable measurement techniques.
VI. Other Allegations
Indirect Infringement
The complaint alleges active inducement of infringement, asserting that Crystal knowingly supplies the accused filters to downstream manufacturers like Samsung with the intent that they be incorporated into products (e.g., mobile phones) that are made, used, and sold in the U.S., thereby directly infringing the patents (Compl. ¶¶25, 32, 39).
Willful Infringement
The willfulness claim is based on alleged pre-suit knowledge. The complaint states that Viavi notified Crystal of its infringement "at least as early as July 2021," several months before the lawsuit was filed. Crystal's alleged continuation of infringing activities after receiving such notice is the basis for the allegation of deliberate and willful infringement (Compl. ¶¶14, 29, 36, 43).
VII. Analyst’s Conclusion: Key Questions for the Case
- A central issue will be one of evidentiary demonstration: Can the plaintiff prove, through reverse engineering and testing, that the accused filters sold by the defendant actually meet the specific, quantitative performance limitations recited in the claims, such as the refractive index values and the precise nanometer-scale limits on center wavelength shift?
- The case will also turn on a question of claim scope: How will the court construe the term "hydrogenated silicon layers"? Will the term be limited to the specific, high-performance material produced by the detailed methods disclosed in the specification, or will it be interpreted more broadly to cover a wider range of silicon materials containing hydrogen?
- A key procedural question will be the impact of the IPR: Following the post-filing cancellation of all asserted claims of the ’794 patent, a core question is how the court and parties will proceed, with the case now focused exclusively on the allegations related to the ’269 and ’526 patents.