OPTOFLUIDIC LASER WITH AN ULTRASMALL FABRY-PEROT MICRO-CAVITY

Abstract

An optofluidic laser with an ultrasmall Fabry-Perot (FB) micro-cavity, This optofluidic laser consists of two highly reflective cavity mirrors and a micro capillary. The two reflective minors are arranged in parallel to form a resonant cavity with an output mirror on the top and a total reflective mirror on the bottom of the cavity. The cavity length L is 30-50 m, the reflectance of the total reflective mirror is higher than 99.9% and the transmittance of the output mirror is 2%-10%. The capillary, serving as the pathway for the micro fluid, is placed between the two Bragg reflectors. The two ends of the capillary arc connected to Teflon soft tubes. The solution containing either gain medium or biological samples is transported to the FB micro-cavity through the soft tubes. The biological samples pass through the water-soluble or organic liquid gain medium in the micro fluid chamber with a certain speed and, under irradiation of a pumping light, produce high intensity, narrow-band output laser signals. The current invention replaces the traditional fluorescent signals with laser signals as the sensing and imaging medium, to achieve biological sensing with ultra-sensitivity and biological imaging with ultra-resolution.

Claims

1. An optofluidic laser with an ultrasmall Fabry-Perot micro-cavity, comprising: two highly reflective cavity mirrors and a micro capillary having two ends, of which the two mirrors are parallel distributed Bragg reflectors (DBRs) to form a resonant cavity with an output mirror on a top and a total reflective mirror on a bottom of the cavity, wherein the cavity has a length L of 30-50 m, the total reflective mirror has a reflectance of higher than 99.9%, and the output mirror has a transmittance of 2%-10%; of which the capillary, either square or rectangular, serving as a pathway for a micro fluid, is placed between the two Bragg reflectors, the two ends of the capillary are connected to Teflon soft tubes, and a solution containing either gain medium or biological samples is transported to the Fabry-Perot micro-cavity through the soft tubes.

2. The optofluidic laser with an ultrasmall Fabry-Perot micro-cavity according to claim 1, wherein a parallelism of the two surfaces of the each DBR is less than or equal to 3.

3. The optofluidic laser with an ultrasmall Fabry-Perot micro-cavity, according to claim 1, wherein a parallelism of the surfaces of the total reflective mirror and the output mirror in the cavity is in the range of 5 to 10.

4. The optofluidic laser with an ultrasmall Fabry-Perot micro-cavity, according to claim 1, wherein, the material for the two parallel distributed Bragg reflectors is artificial quartz crystal.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0017] FIG. 1 is the schematic showing the optical platform for this invention. It utilizes a nano-second OPO pumping source (UV-NIH, tunable nano-second laser, 192-600 nm, maximum power 50 mJ/pulse, pulse width 3-5 nm, repetitive rate 10 Hz) and a fluorescent microscope (Olympus BX53).

[0018] FIG. 2 is the schematic showing the optofluidic micro-cavity.

[0019] FIG. 3 shows the laser spectrum from the Fabry-Perot micro-cavity. (a) Laser spectrum from the Fabry-Perot micro-cavity, (b) Spectrum in a narrow wavelength range.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] This invention is, further described using the following example: laser pumping experiment with the micro-optofluidic chamber using alcohol containing coumarin dye as the gain medium. [0021] 1. Sample Preparation. Fabry-Perot micro-cavity is prepared as shown in FIG. 2. First, place one or two drops of MY131 UV glue on one side of the rectangular capillary and then place the total-reflective mirror on the glue, followed by solidification with UV light. Fix the output mirror on the other side of the capillary following the same procedures. Seal the ends of the two Teflon tubes with the two ends of the capillary using NOA81 to ensure the sample in the micro optofluidic cavity is airtight. [0022] 2. Methods of Measurement. First, transport the alcohol solution containing coumarin dye with a micro fluid pump into the micro fluid chamber with a certain speed, using a nano-second OPO laser as the pumping source and a microscope system (Olympus BX53) to focus the light on the top of the micro chamber. The laser signals from the output mirror are collected by a CCD spectrometer and the data are stored and analyzed. As shown in FIG. 3, the laser signals collected by this novel system have excellent periodicity, transmitted in single longitudinal mode, with a free spectral range (FSR) of 0.44 nm.