POWER OF ATTORNEY


     The undersigned hereby constitutes and appoints each of Sheela Kosaraju,
Erik J. Lichter and Michelle Rankin, or their respective assignees, each signing
singly, the undersigned's true and lawful attorney-in-fact to:

     (1) execute for and on behalf of the undersigned Form ID, Forms 3, 4 and 5,
         and all amendments thereto in accordance with Section 16(a) of the
         Securities and Exchange Act of 1934, as amended, and the rules
         thereunder;

     (2) do and perform any and all acts for and on behalf of the undersigned
         which may be necessary or desirable to complete and execute any such
         Form ID, Form 3, 4 or 5, or any amendment or amendments thereto and
         file such form with the United States Securities and Exchange
         Commission, the New York Stock Exchange, the Nasdaq Stock Market and
         any other authority; and

     (3) take any other action of any type whatsoever in connection with the
         foregoing which, in the opinion of such attorney-in-fact, may be of
         benefit to, in the best interest of, or legally required by, the
         undersigned, it being understood that the documents executed by such
         attorney-in-fact on behalf of the undersigned pursuant to this Power of
         Attorney shall be in such form and shall contain such terms as such
         attorney-in-fact may approve in such attorney-in-fact's discretion.

       The undersigned hereby grants to each such attorney-in-fact full power
and authority to do and perform any and every act and thing whatsoever
requisite, necessary, or proper to be done in the exercise of any of the rights
and powers herein granted, as fully to all intents and purposes as the
undersigned might or could do if personally present, with full power of
substitution or revocation, hereby ratifying and confirming all that such
attorney-in-fact, or such attorney-in-fact's substitute or substitutes, shall
lawfully do or cause to be done by virtue of this power of attorney and the
rights and powers herein granted.  The undersigned acknowledges that the
foregoing attorneys-in-fact, in serving in such capacity at the request of the
undersigned, are not assuming any of the undersigned's responsibilities to
comply with Section 16 of the Securities Exchange Act of 1934, as amended.  This
Power of Attorney can only be revoked by delivering a signed, original
"Revocation of Power of Attorney" to the attorney-in-fact and shall remain in
full force and effect until such revocation is delivered.

       IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed as of this 30th day of August, 2023.

                                             /s/ Mary G. Puma
                                             _________________________________
                                             Signature

                                             Mary G. Puma
                                             _________________________________
                                             Print Name