In-Line Fiber Partial Reflector

Partial Reflectors with Internal Reflective Coating
1450 nm - 1650 nm Wavelength Range
67:33 or 10:90 Reflection Ratio (R:T)
Available with FC/PC or FC/APC Connectors

Input Light

Transmitted Light

Reflected Light

RW1550R2A

10:90 Partial Reflector with FC/APC Connectors

RW1550R3F

67:33 Partial Reflector with FC/PC Connectors

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Partial Reflectors for In-Line Fiber Applications
Internal Reflective Coating with 67:33 or 10:90 Reflection Ratio (R:T)
1450 nm - 1650 nm Wavelength Range
Available with 2.0 mm Narrow Key FC/PC or FC/APC Connectors

Thorlabs’ In-Line Partial Reflectors are designed to partially reflect the input light; a portion is reflected back towards the input end while another fraction is transmitted to the output. This is achieved by splitting the input light and using an internal reflective coating to direct the light back towards the input. Unlike our beamsplitter-coated patch cables, neither of the connector ends are coated; therefore, these partial reflectors can be mated to other patch cables for completely in-line operation. When used with a fiber optic circulator, these reflectors offer a solution for all-fiber beamsplitting (see the Applications tab) and are useful for applications such as round trip delay timing.

These partial reflectors have a 1450 nm - 1650 nm single mode wavelength range with either a 67:33 or 10:90 reflection ratio. The reflection ratio (R:T ratio) is the ratio of reflected light to transmitted light not including light lost within the device due to absorption. The white port is used as the input; please note that these partial reflectors cannot be used in the reverse direction. Partial reflectors are offered from stock with FC/PC or FC/APC connectors, as outlined in the table below. Fiber leads are jacketed in Ø900 µm Hytrel^®* tubing and are 0.8 m long. Custom configurations with other wavelengths, fiber types, or R:T ratios are also available; please contact Tech Support with inquiries.

Each partial reflector includes two protective caps that shield the ferrule ends from dust and other hazards. Additional CAPF Plastic Fiber Caps and CAPFM Metal Threaded Fiber Caps for FC/PC- and FC/APC-terminated ends are also sold separately. Mating sleeves are available to couple patch cables together and serve to minimize back reflections and ensure proper alignment of the cores of each connected fiber.

*Hytrel^® is a registered trademark of DuPont Polymers, Inc.

Click to Enlarge
Figure 1: All-Fiber Beamsplitter Setup

All-Fiber Beamsplitting

Fiber partial reflectors are useful in creating a variety of devices such as beamsplitters, laser cavities, and interferometers. These fibers reflect a fraction of the light back down the fiber, transmitting the remainder through the output fiber connector.

This property is especially useful for creating an all-fiber beamsplitter; the user can split a light source without requiring free space coupling using a beamsplitter cube. Figure 1 shows this simple setup made up of a fiber circulator and a 67:33 fiber partial reflector. Light is input into Port 1 of the circulator, with the partial reflector coupled to Port 2. The input light is coupled from Port 1 to Port 2; roughly 33% of the light is transmitted through the fiber output, and the remainder is reflected back towards the input and directed towards Port 3 by the circulator.

Posted Comments:

user (posted 2021-07-06 10:51:45.783)

For the In-Line Fiber Partial Reflectors, the notes say it cannot be used in the reverse direction. But what happens when light does enter in the reverse direction? For example, is it very lossy? Thanks

YLohia (posted 2021-07-07 02:58:45.0)

Thank you for contacting Thorlabs. This product is essentially a 2x2 coupler, except that one output has a highly reflective coating, and the second input is internally terminated. The end product is a 1x1. Therefore, the losses will be quite high when being operated in reverse.

Simon Boiviner (posted 2019-06-18 11:40:52.16)

Hi, Have you any PM version of RW1550R3A component ? Reagrds, Simon

YLohia (posted 2019-06-20 08:43:47.0)

Hello Simon, thank you for contacting Thorlabs. Quotes for custom items can be requested by emailing techsupport@thorlabs.com. I have reached out to you directly to discuss the possibility of offering this.

masahiro.watanabe.ub (posted 2017-02-22 10:57:16.757)

Selection of the reflectance should be allowed. Only R = 67% is not useful. I am looking for inline partial reflector with R = 4%. R = 10% and 33 % would also be useful.

tfrisch (posted 2017-03-02 02:10:01.0)

Hello, thank you for sharing your feedback on what other ratios would be useful. I will reach out to you directly about our custom capabilities until we release more versions to our stock.

67:33 Reflection Ratio (R:T)

Item #^a	Info	Center Wavelength	Bandwidth	Reflectance^b (Click for Plot)	Transmission^c(Click for Plot)	Reflection Ratio^d	Fiber Type^d	Termination
RW1550R3F		1550 nm	±100 nm	45.0 ± 4.5% (3.5 ± 0.4 dB)	22.5 ± 2.5% (6.5 ± 0.5 dB)	67:33	SMF-28	FC/PC
RW1550R3A		1550 nm	±100 nm	45.0 ± 4.5% (3.5 ± 0.4 dB)	22.5 ± 2.5% (6.5 ± 0.5 dB)	67:33	SMF-28	FC/APC

All values are specified at room temperature over the bandwidth and measured with connectors using the white port as the input.
Total Reflected Output at the White Port
Total Transmitted Output at the Red Port
Ratio of Reflected to Transmitted Output
Corning SMF-28 fiber type will be specified on the documentation that ships with the coupler. Other fiber types may be available upon request. Please contact Tech Support with inquiries.

10:90 Reflection Ratio (R:T)

Item #^a	Info	Center Wavelength	Bandwidth	Reflectance^b (Click for Plot)	Transmission^c(Click for Plot)	Reflection Ratio	Fiber Type^d	Termination
RW1550R2F		1550 nm	±100 nm	7.2 ± 2.7% (11.4 ± 2.0 dB)	65.0 ± 5.0% (1.9 ± 0.1 dB)	10:90	SMF-28	FC/PC
RW1550R2A		1550 nm	±100 nm	7.2 ± 2.7% (11.4 ± 2.0 dB)	65.0 ± 5.0% (1.9 ± 0.1 dB)	10:90	SMF-28	FC/APC

All values are specified at room temperature over the bandwidth and measured with connectors using the white port as the input.
Total Reflected Output at the White Port
Total Transmitted Output at the Red Port
Ratio of Reflected to Transmitted Output
Corning SMF-28 fiber type will be specified on the documentation that ships with the coupler. Other fiber types may be available upon request. Please contact Tech Support with inquiries.