波導耦合鈮酸鋰微碟形元件之研究

Study of waveguide-coupled microdisk resonators on lithium niobate

陳宗德(Tsung-Te Chen)

指導教授 ： 王子建

國立臺北科技大學/電資學院/光電工程系研究所/碩士(2013年)

摘要

本論文使用離子佈植與濕式蝕刻技術，在鈮酸鋰 -Z面上製作出具有底切結構之波導耦合微碟形元件，此結構上下介質為空氣，具有橫向與縱向高折射率對比，使光場更能夠被侷限在波導與共振元件裡，而降低光傳播時所造成的損失。製程上，分別使用鉻膜以及光阻作為濕式蝕刻與離子佈植之遮罩，離子佈植後以稀釋氫氟酸蝕刻離子佈植區域，使其對結構底部進行蝕刻，以形成懸浮之結構。由於蝕刻過程會使結構邊緣不平整而產生粗糙表面，增加元件表面散射損耗，實驗中使用表面熱流處理製程，以接近物質熔點的高溫使晶片表面具流動性，藉由表面張力而達到修飾表面平整度的目的。論文中說明鉻膜對蝕刻製程及佈植遮罩品質對蝕刻表面的影響，並成功製作出碟形直徑分別為20μm、40μm、60μm，耦合間距為0μm、1μm之完整元件結構，元件是使用光波導將光場耦合至微碟形元件中，分別對未熱流與熱流1hr之直徑20μm微碟形元件進行量測。未熱流微碟形元件FSR約為16.051nm、品質因子1.66×103，而熱流1hr微碟形元件FSR約為15.646nm、品質因子5.89×103。從品質因子知，將表面熱流處理製程應用在波導耦合微碟形元件上的確能有效降低損耗，並獲得更高的品質因子。並透過品質因子對比，探討光纖耦合微碟形元件之品質因子較高之原因，並分析熱流溫度、熱流時間以及微碟形耦合結構之差異對於品質因子之影響。

關鍵字

鈮酸鋰 ； 波導耦合 ； 微碟形 ； 共振元件 ； 離子佈植

並列摘要

This thesis use ion implantation and wet etching techniques in -Z face of the lithium niobate produced undercut waveguide-coupled microdisk resonator. Because the air around the structure which have high horizontal and vertical refractive index contrast, so that the light is confined inside the waveguide and microdisk resonators, and also reduce the propagation loss.
In process, we use chromium film and photoresist as a mask of wet etching and ion implantation. For the undercut structure, we use dilute hydrofluoric acid to etch implantation region after ion implantation so that the bottom of the structure is etched to form an undercut structure. Since the etching process can cause rough edges which increasing scattering loss, so we use heat flow process to smooth surface. This thesis describe the quality of chromium film and implant mask can have a significant impact on devices, and successfully produce the device which disc diameter is 20μm, 40μm and 60μm, and coupling gap is 0μm and 1μm, respectively. This device use waveguide coupled method, and measure the microdisk of 20μm in diameter which is non-heat flow and heat flow, respectively. FSR is about 16.051nm, and Q factor is 1.66×103 of the non-heat flow device. FSR is about 15.646nm, and Q factor is 5.89×103 of the heat flow device. From the Q factor, the surface heat treatment process used in waveguide-coupled microdisc resonators can effectively reduce losses and get a higher Q factor. Comparing the Q factor, we discussed the reasons for the higher Q factor of fiber taper microdisk and analyze heat temperature, heat flow time, and the difference between these resonators.

並列關鍵字

lithium niobate ； waveguide-coupled ； microdisk ； resonator ； ion implantation

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