FABRY-PEROT ETALONS0 pages

fabry-perot etalons
Fabry-Perot etalons are made up of two parallel partially reflecting mirrors facing each other. The interference created by the mirrors acts as
a filter which transmit only a series of resonnance peaks evenly distanced in frequency domain. The distance between mirrors defines the
distance between peaks in frequency domain, while mirrors reflectivity define peaks width. High quality polishing (λ/20) and excellent
parallelism (< 1 arcsec) ensure high finesse and transmission characteristics.
To produce air gap etalon, one needs to use a frame to support the mirrors at both ends of the air gap. In order to achieve high thermal and
mechanical stability, we use a glass with low thermal expansion coefficient, i.e., Zerodur® as spacer material. Air spaced etalons are easier
to customize than solid glass etalons. The mirrors from the same coating batch can be used for any air-gap, while the distance between
mirrors is adjusted by changing holder length. To avoid back-reflection, the other side of the mirror glass plate can be polished with a small
wedge angle. Solid etalons are made from a piece of glass of exact thickness which is coated on both sides with partially reflecting coating.
Their sensivity to temperature variation can be used to tune the etalon within an environment with controlled temperature. Fabry-Perot
etalons are in common use in telecom systems as narrow band filters to lock a laser cavity on a fixed frequency or as a frequency reference
comb according to ITU grid. Doric Lenses Inc. etalons are also used in diverses applications such as astromony, optical transport, optical
sensing and others.

WEBCODE:

D104-xxx
DRAWING

SPECIFICATIONS

SYMBOL

VALUE

Operation Wavelength

λ0

1550 nm

Height

H

17 mm

Width

W

14 mm

Length

L

Free Spectral Range

FSR

80 mm
7.5 GHz

Finesse

15 GHz
4

-

-

50 GHz

10

A : air space with Zerodur spacer
B : solid fused silica etalon

Cavity type
Insertion Loss

-

I.L.

< 2.0 dB

Operating Temperature

15 to 40°C

Storage Temperature

-20 to 85°C

NOTE

All specifications are customized upon request

p. 1/1
FABRY-PEROT ETALON (12/07)
www.doriclenses.com
418.877.5600