Programmable Coupler Ladder Based on Lithium Niobate Y-Junction Reflector

Jianxiao CHEN
Tetsuya KAWANISHI
Kaoru HIGUMA
Satoshi SHINADA
William S.C. CHANG
Masayuki IZUTSU
Paul K.L. YU

Publication
IEICE TRANSACTIONS on Electronics   Vol.E88-C    No.3    pp.379-384
Publication Date: 2005/03/01
Online ISSN: 
DOI: 10.1093/ietele/e88-c.3.379
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Optical Signal-Processing Devices for Photonic Networks)
Category: 
Keyword: 
lithium niobate,  splitter,  coupler ladder,  loop resonator,  

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Summary: 
This paper presents a proposal for a novel integrated tunable coupler device called programmable coupler ladder, based on Titanium diffused lithium niobate waveguide and Y-junction reflector. Unlike the traditional serial to parallel converter, the coupler ladder sorts the output bits in the time axis using a built-in delay waveguide. With a proper control signal it can perform signal processing at the bit level. It also can generate coherent multi-channel outputs with theoretically arbitrary amplitude and phase from continuous input light source. Its application in optical microwave beam forming is briefly described. The key component, built-in delay line based on Y-junction reflector, has been experimentally verified via a loop resonator structure. 1 dB loss is found for each Y-junction reflector, which enables a practical coupler ladder. The loop itself is also an important device for optical signal processing.