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Browse Prior Art Database

Nonlinear Subresonator for Laser Passive Mode Locking

IP.com Disclosure Number: IPCOM000121860D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 82K

Publishing Venue

IBM

Related People

Edelstein, DC: AUTHOR [+3]

Abstract

An optical subresonator is disclosed which allows spontaneous, passive mode-locking of many different dye or solid-state lasers which possess suitable gain bandwidth to allow ultra-short pulse generation.

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

Nonlinear Subresonator for Laser Passive Mode Locking

      An optical subresonator is disclosed which allows
spontaneous, passive mode-locking of many different dye or
solid-state lasers which possess suitable gain bandwidth to allow
ultra-short pulse generation.

      The subresonator is shown in the figure and replaces one end-
mirror of a standard, linear-cavity laser, such as Nd:YAG, Nd:YLF,
Ti:A1203, NaC1:OH, RH6G, etc.  The subresonator consists of: a half-
wave retardation plate (HWP); a block of birefringent material such
as calcite, suitably cut to act as a polarizing beamsplitter based on
the double-refraction principle (BBS); two equal lenses or curved
mirrors of N50 mm focal length (L1, L2); a Brewster-angle-oriented
glass compensating plate (BCP); a flat, high-reflecting-end mirror
(M), and finally, a thin (N1 mm) platelet of nonlinear organic
crystal (X), such as DAN, MNA, MMONS, etc.

      When laser light polarized as shown is incident on HWP, an
adjustable portion will propagate as an extraordinary wave (e-wave)
in BBS and will be split off from the main beam, which is an ordinary
wave (o-wave).  The two beams emerge parallel but displaced.  One of
these beams is focussed through the nonlinear crystal X, while the
other passes through BCP which equalizes its optical path length to
the other beam.  Both beams retrace themselves after hitting M and
are recombined by BBS and HWP to exit the subresonator as linearly
polarized light again.  The light focused through X undergoes
self-phase modulation (SPM) in proportion to its intensity, as
determined by the third-order hyperpolarizability of the crystal.
When the two beams are recombined interferometrically, BCP is
empirically adjusted so that the peak of a pulse or fluctuation is
enhanced while the wings are diminished by constructive and
destructive interference, respectively, as given by the theory of
additive-pulse mode-locking [1]. Afte...