Browse Prior Art Database

Improved Prism Coupler Apparatus

IP.com Disclosure Number: IPCOM000119357D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 71K

Publishing Venue

IBM

Related People

Fan, B: AUTHOR [+3]

Abstract

Disclosed is a mechanical improvement to the load bearing arrangement of a prism coupler apparatus.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Improved Prism Coupler Apparatus

      Disclosed is a mechanical improvement to the load bearing
arrangement of a prism coupler apparatus.

      Prism couplers are used to excite guided optical modes in thin
films [1].  Also, existing guided modes can be coupled out from the
films.  This can be accomplished with two right angle prisms or a
single roof prism.  Optical coupling is established by forcing the
prism against the film which is to be characterized.  The refractive
indices of both the prism and the film's substrate are assumed to be
known.  The measurement is essentially one of accurately determining
the angle of incident and/or exiting laser beam, corresponding to
identified guided modes, relative to the normal to the prism
hypotenuse.  The data from the measurement can be used to accurately
calculate the thickness and refractive index of the film.  This is
commonly known as m(ode)-line spectroscopy.  Also, information on
attenuation guided modes can be obtained.  Here, optical modes are
selectively excited in a film with a right angle prism and the
scattered light from the propagating mode is analyzed.  For optical
coupling, an air gap of   0.2 mm is required between prism and film.
This gap is normally established by varying the mechanical force
between the prism base and the film.  Independent of the means used
to establish the optical coupling, it is clear that the quality
(parallelism, flatness, and cleanliness) of the surfaces must be
under reasonable control.  Also, it is clear that the p...