High-Speed Modulation Characteristics Of The Tunable V-Cavity Laser

Breakthroughs in optical communication technology has been the foundation of the fast-developed Information Era.And the need for the optical transmission capacity of the growing information era is endless.The need for capacity also greatly promoted the techniques of the optical communication on the contrast.WDM(wavelength-division multiplexing)is the milestone of the optical communcation technology and is the most widely used technology in today's optical network.The WDM together with the coherent communication techniques is accelerating the bit rate of the backbone network from 100Gb/s to 400Gb/s,even 1Tb/s in the near future.The access network now becomes the bottleneck,although 10G-PON is grow rapidly in recently years.WDM technology comes into the access network is foreseeable,therefore a huge market for low-cost tunable laser diodes appears.In this thesis,we study a kind of low-cost tunable laser,the V-Cavity laser(VCL),developed by JianJun-He,Zhejiang University professor.The VCL doesnot need any grating structure,neither does epitaxy regrowth.And the VCL need only one electrode for wavelength tuning,simplify the tuning algorithm.All these features make the VCL low cost.The VCL consists of two Fabry-Perot cavities with slightly different optical path lengths,and uses the Vernier effect for tuning.In order to ensure high side-mode-supression ratio(SMSR),the VCL contains a half-wave coupler,which can add another wavlength-selecting method by introducing a wavelength-dependent loss.All these ensure a perfect VCL.We focus on the high-speed modulation characteristics of the VCL in this paper.By testing the frequency response,chirp characteristics,eye diagram and BER to fully understand its ability under direct modulation.We introduce InGaAlAs material to VCL as one of the methods to improve the modulation behavior because of the large differential gain of the aluminum-contained material,other methods include optimizing the cavity structure.The most important method is the 200GHz channel spacing design.This design reduces the cavity volume a lot in order to improve the high frequency response,and can also balance the tuning range with the SMSR in a much better way by adopting a new tuning method which uses different temperature control to achieve 100GHz spacing in a 200GHz spacing designed VCL.Chirp managed laser technology is also discussed and introduced to VCL in this paper.VCL achieves 10Gb/s modulation speed with CML and this can be a candidate for VCL working under 10Gb/s speed.Another candidate,the VCLintegrated with EAM,is not only introduced,but also designed in this paper.We choose quantum well intermixing to be the integration platform and the coupling of the VCL and EAM is discussed in detail.Besides,we also introduce and optimize the thermally tuned version of the VCL.Unlike the traditional version,the thermally tuned version integrated with thin-film resistor to generate heat as a tuning method.Further,we plan to add heater on chip to make the TO package coolerless,to reduce the cost to a new level.We believe the VCL is very promising for the next generation WDM-based applications.