What Substrates are Used for Optical Waveguide Research?

university wafer substrates

SOI Wafers to Fabricate Optical Waveguides

A PhD student requested the following:

I have received my SOI wafer. It has 250nm silicon layer with 2um oxide layer beneath. We will use it to fabricate silicon optical waveguide.

BTW, do you have any information of cutting/cleaving SOI wafer? We are not sure if it is just the same as cleaving the common silicon wafer in lab? by the diamond pen is ok?

Reference #47079

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SOI Platform to Fabricate Optical Waveguides

A graduate student requested a quote for the following:

I am working in integrated photonics and I am trying to make optical waveguides using an SOI platform. I need to purchase an SOI wafer but I was wondering if you know what doping level/resistivity would be appropriate for optical waveguide fabrication? My understanding is that a highly doped wafer would create losses due to the free carriers, so I am wondering if I need to use a wafer which has no doping? I thought to ask you because maybe you have dealt with this before for other customers. I am looking for a device layer thickness of 220-250nm, orientation <100>, bottom oxide layer 2-3um, diameter 150mm. I'm just not sure what doping works best for photonic applications.

I am really just wondering if you know if the doping of the device layer will negatively affect the propagation loss in SOI waveguides. For example, you currently have a wafer in stock with ID 3381 which is 150mm diameter, P type doping, <100> orientation, 220nm device layer thickness and 2um BOX layer thickness. The resistivity is listed as 10-20 ohm-cm, which I believe corresponds to about 10^15 doping concentration (correct me if I'm wrong). This is the wafer I have been using in my experiments so far, but I am wondering if that doping is causing any propagation loss. I am trying to minimize propagation loss by adjusting my fabrication steps, but maybe I also need to use an undoped wafer to further reduce my propagation loss? Do you know if your other customers are using this doping concentration in SOI waveguides?

Reference #259923 for specs and pricing.


What Substrates are used to Fabricate Optical Waveguides?

Optical waveguides are structures that guide light from one point to another, typically using the principle of total internal reflection. They are used in various devices like fiber optic cables and integrated optical circuits.

The choice of substrate used for fabrication of optical waveguides largely depends on the required properties such as optical transparency, refractive index, and mechanical and thermal stability. Various materials have been used to fabricate optical waveguides, including:

  1. Silica (SiO2): This is one of the most common materials used for making fiber optic cables, which are a form of optical waveguide. Silica is preferred for its low loss at telecom wavelengths, high thermal stability, and robust mechanical properties.

  2. Silicon (Si): Silicon is often used as the substrate in silicon-on-insulator (SOI) waveguides. The high refractive index contrast allows for tight bending radii, which is important for miniaturization in photonic integrated circuits.

  3. Silicon Nitride (Si3N4): Silicon nitride is another commonly used material for fabricating waveguides, particularly for applications that require lower optical losses and broader wavelength operation than is typically achievable with silicon.

  4. Polymers: Polymers such as PMMA (poly(methyl methacrylate)) or Ormocers can be used for the fabrication of optical waveguides, particularly for short distance communications, due to their ease of processing and ability to be directly written on.

  5. Glasses: Certain types of glass, such as phosphate and chalcogenide glasses, can be used to fabricate waveguides. They are often chosen for their unique optical properties such as high nonlinearity or broad transmission windows.

  6. Lithium Niobate (LiNbO3): Lithium niobate is a popular substrate for waveguides, particularly in applications that require high electro-optic coefficients, such as in modulators.

  7. III-V Semiconductors: Semiconductors such as Gallium Arsenide (GaAs) and Indium Phosphide (InP) are used when active devices, such as lasers or amplifiers, need to be integrated into the waveguide.

In addition to these, other materials such as diamond, aluminum oxide (Al2O3), and various types of crystal materials (e.g., potassium titanyl phosphate (KTP), potassium dihydrogen phosphate (KDP), etc.) are used in specific applications.

Fused Silica Glass to Fabricate Optical Waveguides

A researcher from a large university engineering department requested the following:

My research group is looking to purchase fused silica wafer for optical waveguide fabrication. I was wondering what is the highest grade fused silica wafer available and what is its surface roughness. On the University Wafer website, it was mentioned that fused silica wafer (ID: 1943) can be used for optical grade experiments. I was wondering if you could let me know what is the surface roughness for this wafer as well.

Reference #276059 for specs and pricing.

Thermal Oxide Coated Silicon Wafers to Fabricate Optical Waveguides

A optical researcher requested the following quote:

Our main purposes is for educational and optics postgraduate program at our university. In particular, we have some Thesis projects related with basic synthesis of submicron optical waveguides i.e. Al2O3, TiO2, etc. ) see atached ref. And we are considering use Si wafer with SiO2 layer as sustrates.

Please send me the formal quotation for

Silicon 100mm P/B (100) 1-10 ohm-cm 500um SSP PRIME with 4um WET Thermal

Reference #261959 for specs and quantity.