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PROFA™: Pitch Reducing Optical Fiber Array – Two-Dimensional (2D)

PROFA™: Pitch Reducing Optical Fiber Array – Two-Dimensional (2D)

Pitch Reducing Optical Fiber Arrays (PROFAs) provide low loss coupling between standard optical fibers and photonic integrated circuits.

Unlike typical fiber arrays, they also provide high density coupling that minimizes the valuable chip real estate needed for optical input/output (I/O). They can provide spot size conversion between small cross-section, chip-based waveguides and standard optical fibers.

Two-dimensional (2D) PROFAs are used for chip surface coupling to vertical grating couplers with mode field diameters of approximately 6 or 10 µm or to chip-based devices such as VCSELs or photodiodes. Standard 2D PROFAs are available as hexagonal lattice arrays with up to 61 channels.

One-dimensional (1D) PROFAs (see separate PROFA1D datasheet) are available in standard linear arrays of one to six channels and are typically used for chip edge coupling to waveguides with approximately 2 µm diameter mode field sizes.

Please speak to us about other mode field sizes and lattice configurations which have been addressed with custom PROFAs. Custom PROFAs have been supplied to address different channel counts, channel spacing, wavelengths and configurations:

PROFA2D Benefits

Form Factor/High Density: Typical lenses cannot be packed closer than 125 microns, compromising the inherent density achievable on-chip. This advantage becomes even more compelling when an arrayed interconnect is of interest.

Polarization: Many waveguides are polarization sensitive and maintaining polarization through a lens to small waveguides is challenging if not impossible. Currently only PROFA2Ds are available in SM versions. Speak to us about your PM PROFA2D needs.

Robust connection: PROFAs are intended to be butt coupled or surfaced coupled. Eliminating the air gap minimizes the effects of thermal excursions in the package and dust that can make its way into the optical path. The monolithic all-glass construction enables sealing via adhesives or glass or solder (with metallization) for hermiticity, as needed.

Cost: In addition to performance advantages, the PROFA is competitively priced in volume quantities.

PROFAs are also used within coupled and packaged solutions that Chiral Photonics can provide.

For your photonic integrated circuit packaging needs, please be sure to contact us for our Optical Coupling & Packaging Design Guide which contains packaging recommendations to assist in your design work. To request a copy, send an e-mail to [email protected].

PROFA2D Specifications

Speak to us about your custom or OEM needs. Custom PROFAs have been supplied to address different channel counts, wavelengths and configurations:

Central Wavelength 1 nm 1550
Mode Field Size 2 µm 9-11
Bandwidth nm > 50
Insertion Loss 3 dB < 1 dB
Optical Return Loss 4 dB < -40
Crosstalk dB < -35
Number of Channels 5 2-91
Channel Spacing 6 µm 35 – 50
Typical Avg. Channel Position Deviation 7 µm ≤ 0.6 / ≤ 1
Pigtails 8 SM, 1 meter long, coated fiber
Operating Temperature C -40 to +85
Storage Temperature C -70 to +85
Package Type 9 See Dimensional Drawings
  1. Other wavelengths available upon request.
  2. Measured as 1/e2 intensity. Other mode field sizes available upon request.
  3. Measured from fiber pigtail to device tip, per channel.
  4. Intrinsic to device.
  5. Typical array is hexagonal. Other lattice arrays have been accommodated. Larger channel counts can also be accommodated.
  6. Other channel spacing sizes can also be accommodated.
  7. ‘Measured error for PROFA relative to “perfect array” channel position. Will be dependent on array size and pitch.
  8. Other pigtails, connectorization and other pigtail lengths available upon request.
  9. Please speak to us about your custom package and splicing needs.



Ordering Information

When purchasing a PROFA2D, please use the guide below to determine the best configuration for your application.

Exemplary Configurations

PROFA2D, 7-channel

  • 35 µm channel spacing
  • SMF28 fiber pigtails 1 meter long
  • 1550 nm central wavelength
  • LC/APC connectors, unjacketed, flat endface
  • minimal package

PROFA2D, 4-channel

  • 50 µm channel spacing
  • SMF28 fiber pigtails 2 meters long
  • 1550 nm central wavelength
  • FC/UPC connectors, jacketed, flat endface
  • holder compatible package

PROFA2D, 61-channel

  • 40 µm channel spacing
  • SMF28 fiber pigtails 3 meters long
  • 1550 nm central wavelength
  • no connectors, unjacketed, 8° angled enface polish
  • holder compatible package

Technical Notes

Cleaning and Care: PROFAs are all-glass and, therefore, can be cleaned with alcohol much like a bare fiber tip. Care must be taken to avoid breaking or chipping the tip as any damage to the tip will likely cause the device to be unusable.

Alignment, Coupling and Packaging: The device is aligned similarly to other micro-optic devices, e.g. similar to working with lensed fibers. Using the PROFA, the most efficient and stable coupling is achieved by butt coupling the device to the waveguide. Often customers will use index matching liquids or adhesives but this is not required.

PROFA standard products are rigid fiber optic couplers. This product is often used in probing. However, in packaging, when attaching to a die, we typically use a PROFA with a flexible tip. This flexibility enables the PROFA-die interface to be mechanically decoupled from the package. We have developed processes and materials for packaging that may vary, depending on the application needs.

Chiral Photonics will be very supportive in transferring the materials knowledge and process knowledge to our customers. There is a fair amount of customization with regard coupling that depends on the design (e.g. channel count, mode field size, SM vs. PM, die edge design and quality) and the application needs. Therefore, we strongly suggest that we work with the customer initially to package the device at Chiral Photonics. After we have done that and the customer has received and is satisfied with the packaging, we can transfer the details of materials and process, if desired, so that the customer can take it in-house and just order the couplers and do the packaging themselves. Ideally, after the customer is satisfied with the initial package, we will be happy to host the customer at Chiral Photonics to see how we packaged the device hands-on. Alternately, we can document the packaging process and materials and make that available to the customer.

Rough Alignment: PROFA2Ds are typically provided with a fiducial marking relative to the numbered channels of the array. This can be used to achieve rough alignment of the PROFA.

Fine Alignment: A five axis stage with at least 1 micron resolution is typically used for XYZ motion as well as angular alignment. The needed stage resolution will depend on the mode field sizes one is working with and the application. A general rule of thumb is 10% of the mode field diameter, or 1 µm for a standard 10 µm PROFA2D. Fine alignment is typically done actively, using two outer channels of the array.